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Elisabeth Huemer Dissertation Definition

© 1998

Michael Huemer

All rights reserved



Michael Huemer

A dissertation submitted to the Graduate School-New Brunswick Rutgers, the State University of New Jersey

in partial fulfillment of the requirements for the degree of

Doctor of Philosophy

Graduate Program in Philosophy

written under the direction of

Professor Peter D. Klein

and approved by

New Brunswick, New Jersey

May, 1998


A Direct Realist Account of Perceptual Awareness


Dissertation Director:

Peter D. Klein

The dissertation presents a direct realist account of our awareness of the external world, embodying two main theses: First, in normal cases, sensory experiences constitute direct awareness of the external world; second, certain beliefs about the external world are prima facie justified by virtue of being based on sensory experiences.

In the first chapter, I explain the concept of awareness and the distinction between direct and indirect awareness. Direct awareness of x is understood as awareness of x which is not based on awareness of anything else, and the "based on" relation is understood as a particular way in which one state of awareness can be caused by another state of awareness when the contents of the two states are logically related.

In chapter 2, I defend a traditional account of perception according to which perceiving can be analyzed into three components: (a) the occurrence of a purely internal mental state, different from belief, called a "perceptual experience", (b) the existence of an external object roughly satisfying the content of the experience, and (c) an appropriate causal connection between the object and the experience.

In chapter 3, I examine the nature of sensory experiences, distinguishing three important aspects of them: their qualia, their representational contents, and their "forcefulness." The content of experience is further divided into conceptual content and non-conceptual content. The attribute of experience by which the objects of experience seem to the subject to be actually present is called "forcefulness."

In chapter 4, I consider how perception leads to knowledge of the external world. I defend an epistemological principle according to which the circumstance of its seeming to S as if P constitutes prima facie justification for S to believe that P. As a result, we are prima facie justified in believing propositions that are entailed by the contents of our experiences.

In the fifth and final chapter, I show how the direct realist theory developed avoids three important kinds of philosophical skepticism: first, Hume's external world skepticism; second, the regress argument of Agrippa; and third, the brain-in-a-vat argument.


I would like to thank the members of my committee; Peter Klein, Brian McLaughlin, Richard Foley, and Richard Fumerton; for their comments and advice on the work in progress. In addition, I would like to recognize the supererogatory efforts made by professors Klein and McLaughlin towards enabling me to graduate this year. None of these philosophers, of course, is responsible for any mistakes contained in the following work.


Abstract ii

Acknowledgments iv

Introduction 1

1. The notion of direct awareness 10

1.1. Awareness in general 11

1.2. "Awareness" and "knowledge" 24

1.3. Epistemic dependence 26

1.4. Direct vs. indirect realism 44

2. Perception as awareness 57

2.1. The traditional analysis of perception 57

2.2. The radical intellectualist account 60

2.3. Ultra-direct realism 65

2.4. The content-satisfaction condition 81

3. The nature of perceptual experience 102

3.1. Sensory qualia 103

3.2. Non-conceptual content 121

3.3. Conceptual content 130

3.4. The forcefulness of experience 132

4. Perceptual knowledge 136

4.1. The justification of perceptual beliefs 137

4.2. Defense of appearance conservatism 140

4.3. Objections 147

5. Direct realism & skepticism 158

5.1. Hume's problem 158

5.2. The regress argument 165

5.3. The brain-in-the-vat argument 170

5.3.1. Two contemporary responses 171

5.3.2. What's wrong with these replies? 175

5.3.3. The direct realist's response 179

5.3.4. An objection 185

Bibliography 188


In the following pages, I have defended a general theory of perception that answers what are probably the three most important philosophical questions about perception: (1) What is perception? (2) What is it that perception makes us aware of? And (3) how does perception enable us to gain knowledge of the external world? In very broad terms, the theory I have put forward can be described as a version of direct realism -- or, if you like, naive realism.

Start with the first question: What is it to perceive? The act of perceiving something involves three elements: first, there is the occurrence of a certain kind of purely internal, mental state, a 'perceptual experience'; second, there is an external phenomenon that roughly satisfies the content of this state; and third, there is a causal relation between the object and the experience.

That leaves the question of what a perceptual experience is. A perceptual experience is understood as a kind of mental state different from belief, but nevertheless having representational content -- i.e., there is a way that a given perceptual experience represents the world to be. Perceptual experiences also have an attribute I call their "forcefulness": when one has a perceptual experience, the objects of the experience always seem to one to be actually present (this is different from, for example, imagination or mere supposition, which is not forceful). Both of these are necessary characteristics of perceptual experience. In addition, I have answered certain currently much-discussed questions about perceptual experience, namely, whether perceptual experiences have 'non-conceptual content' and whether they have 'qualia'. In both cases I have answered in the affirmative (see chapter 3).

Second question: What does perception make us aware of? Philosophers have traditionally given three answers to this:

(i) Direct realism holds that in perception, we are directly aware of the external world.

(ii) Indirect realism (or "representationalism") holds that in perception, we are directly aware only of certain mind-dependent phenomena (e.g., ideas, sense data, appearings), and we are indirectly aware of external objects.

(iii) Idealism holds that in perception, we are directly aware of mind-dependent phenomena, and we are not aware of anything else.

Idealism is generally regarded nowadays as too prima facie implausible to be considered, so direct and indirect realism remain as the two main alternatives.

Indirect realism has historically been the dominant view among philosophers, but it really is quite an incredible idea. It seems to me that I am right now seeing a table in front of me, and thereby enjoying awareness of that table. This thing of which I find myself aware, I think, has four sides and a brown surface; it is physically in front of me; it exists independently of me; I can sit on it and it will support my weight. It certainly is no mere 'idea' or 'appearance'. Furthermore, there is, as far as I know, no other relevant thing of which I am enjoying awareness in seeing the table. There certainly does not seem to be, in addition to the real table, a second 'table' that exists only in my mind and that I'm also perceiving, nor is there some thing of a kind radically different from a table that I'm perceiving or otherwise apprehending when I see the table. To repeat, it seems obvious that, in seeing the table, there is exactly one object that I'm aware of, and that object is a table. Yet it is this seemingly obvious thesis that Hume, one of the early representationalists, claimed would be "soon destroyed by the slightest philosophy":

The table which we see seems to diminish as we remove farther from it: but the real table, which exists independent of us, suffers no alteration: it was, therefore, nothing but its image which was present to the mind. These are the obvious dictates of reason, and no man who reflects ever doubted that the existences which we consider when we say, this house and that tree, are nothing but perceptions in the mind, and fleeting copies or representations of other existences, which remain uniform and independent.(1)

Admittedly, Hume was one of the more incautious of indirect realists -- surely the indirect realist should not claim that the expression "this tree" typically refers to a perception, rather than to a tree. It is, nevertheless, quite incredible that this thing (the one that I'm now directly aware of, as I (seemingly) view my table) is a mental state or mental object, rather than a table. The story becomes perhaps still more incredible when we hear that I have throughout my life been constantly mistaking mental phenomena for physical objects, and that I have perhaps never once perceived anything without making that mistake. Furthermore, this view generates a problem with respect to our third question, that of how perception enables us to gain knowledge of the external world: if we are only ever directly aware of ideas, how do we know that anything other than ideas exists?

Fortunately, Hume's argument is invalid and his conclusion mistaken. The argument fails because Hume overlooks the possibility that the table we see appears to get smaller but does not actually get smaller -- thus, the real table may, after all, be one and the same with the table we see. In fact, the table we see appears precisely the way one would expect the table to appear, assuming that we did perceive a real table. This tends to confirm that it is the real table we see.(2)

Moreover, we can see that Hume's conclusion is mistaken and that perception is direct awareness of the external world, by turning to the analysis of "direct awareness", while keeping in mind the analysis of perception we have provided. To be aware of a thing is to have at least a roughly accurate representation of it, where the accuracy of the representation is not merely accidental (not merely a matter of chance). To be directly aware of something is to be aware of it, where one's awareness of it is not based on one's awareness of something else (this notion is discussed more fully in chapter 1). Now, in perception, one has a perceptual experience that represents there to be something having certain physical characteristics. For example, my current visual experience represents the table in front of me as being brown and rectangular. My tactile experience represents it as being hard and smooth. Etc. The contents of these experiences are at least roughly satisfied by the real, physical table -- the real table has those characteristics -- and not by anything else. There is no other brown, rectangular, etc., object in the offing. Nor do I have any (relevant) second representational state with another content. (Of course, I might happen to have a second representational state at the same time, but that's beside the point -- no such state is required in order for me to be perceiving the table.) Finally, since my perceptual experience is caused in the normal way by the real table, the accuracy of the representation is non-accidental. So my perceptual experience constitutes direct awareness of the real table, and it does not constitute awareness of any mental item.

Our third main question was, How does perception enable us to acquire knowledge of the external world? Our perceptual experiences cause us to accept certain beliefs about the external world -- these 'perceptual beliefs' are based on perceptual experiences. What makes it epistemically rational to accept such beliefs?

In chapter 4 I argue for the following epistemological principle: if it seems to S as if P, then S is prima facie justified in believing that P. Thus, the forcefulness of perceptual experience makes our perceptual beliefs justified. I argue that this general epistemological principle underlies our epistemic practices in a very fundamental way -- that in fact there is, excluding such epistemically irrational practices as self-deception or religious faith, no other way of forming beliefs than accepting what seems to oneself to be the case. This principle also underlies our ways of evaluating arguments, or even of identifying what counts as an argument, so that it is impossible rationally to argue against the principle.

I show in the last chapter how my account of perception and perceptual belief avoids three traditional arguments for philosophical skepticism. The first of these is the infinite regress argument, due to Agrippa. It begins with the premise that a person knows a proposition only if he has a reason for believing it. Furthermore, the reason must itself be something he knows to be true, so there will have to be a reason for the reason, and a reason for the reason for the reason, and so on. But no person actually has an infinitely long chain of reasons to support any of his beliefs, and it is not permissible for the chain of reasons to circle back on itself, so ultimately all our beliefs must rest on arbitrary assumptions (claims for which we have no reasons). Hence, all our beliefs are unjustified.

My account blocks the threatened regress of reasons. The series ends when it hits perceptual experience: our perceptual beliefs are rendered justified by our perceptual experiences; hence, they are not mere 'assumptions'. However, since perceptual experiences are not beliefs, it cannot be sensibly asked what one's 'reason for' a perceptual experience is. Perceptual experiences (in normal cases) are indeed a kind of awareness, but they are never a form of knowledge (because not beliefs), so the first premise of the regress argument does not apply to them.

The second form of skepticism that my account blocks is one that was mentioned above, in connection with Hume's representationalism -- indirect realist theories face a problem of explaining how one can get from premises about ideas (or sense data, or whatever) to conclusions about the physical world. Hume himself argued that there was no rational way to do it. My direct realist theory has the advantage of avoiding this problem altogether, since certain propositions about the physical world are prima facie justified and hence do not need to be supported with argument.

Third, I consider the brain-in-a-vat argument. In this argument, one imagines a situation in which scientists have removed a brain from its body, keeping it alive in a vat of nutrients. They insert tiny electrodes into the brain, cleverly stimulating the sensory cortex of the brain in precisely the patterns in which the sensory cortex of a brain is normally stimulated when a person is perceiving and interacting with the world. In such a scenario, the brain would undergo exactly the same kind of experiences that a person undergoes during normal life -- in fact, the same kind of experience that you're having right now. This brain would have no way of knowing that it was merely a brain in a vat; everything would seem normal. And this raises the question, How do you know that you're not a brain in a vat, right now? The skeptic will argue something like this:

1. If you were a brain in a vat, you would be having just the sort of sensory experiences you're having now.

2. Therefore, your sensory experiences are not evidence that you're not a brain in a vat. (from 1)

3. Your sensory experiences are the only evidence you have for claims about the external world.

4. Therefore, you have no evidence that you're not a brain in a vat. (from 2,3)

5. Therefore, you don't know that you're not a brain in a vat. (from 4)

6. Therefore, you don't know that you have a body, that you're sitting in this room, etc. (from 5)

The indirect realist should be worried by this argument. On his account, what we are directly aware of is merely what sort of experiences we are having, and it is on that evidence (i.e., that we're having such-and-such experiences) that we must try to build our knowledge of the external world. The skeptic is right to argue that the occurrence of these experiences is no evidence against the brain-in-a-vat hypothesis, since those experiences would occur if the brain-in-a-vat hypothesis were true. But on the direct realist's account, what we are directly aware of -- hence, what we may consider as our available 'evidence' -- is the objects of our perceptual experiences, not our experiences themselves. This may seem like a subtle distinction, but it is of the last importance here. The objects of our perceptual experiences, for the direct realist, are external phenomena. Hence, (3) is clearly false. I do have evidence, other than my sensory experiences, relevant to claims about the external world -- namely, I have the actual physical objects and events that I perceive as evidence for such claims. And taking this into account, (4) is certainly false. Among the evidence I have, for example, is the presence of my two hands. This evidence verifies that I am not a brain in a vat, since a mere brain in a vat has no hands.

This sort of refutation of the brain-in-the-vat hypothesis seems like begging the question; however, it begs the question if and only if ruling out the brain-in-a-vat scenario is a precondition on knowing that one has hands. This is not a precondition under a direct realist form of foundationalism. In fact, as I show in chapter 5, this refutation of the BIV scenario begs the question if and only if one assumes an indirect realist theory of perceptual knowledge; otherwise, the refutation succeeds.

We can see that Thomas Reid's remarks concerning indirect realism are as appropriate today as they were when he wrote them in response to the likes of Locke, Hume, and Descartes (imagine "sense data" substituted for "ideas"):

We shall afterwards examine this system of ideas, and endeavour to make it appear, that no solid proof has ever been advanced of the existence of ideas; that they are a mere fiction and hypothesis ... and that this hypothesis of ideas or images of things in the mind, or in the sensorium, is the parent of those many paradoxes so shocking to common sense, and of that scepticism which disgrace our philosophy of the mind, and have brought upon it the ridicule and contempt of sensible men.(3)

My theory of perception, I think, vindicates common sense -- both with respect to the conviction that we are directly aware of physical things when we perceive, rather than ideas or some such, and with respect to the conviction that we know facts about the physical world as a result of perception. And this is among the chief advantages which I would claim for it.


Stated simply, the thesis of direct realism is that in perception, we have direct awareness of (some parts or aspects of) the external world. The task of the present chapter is to provide an interpretation of this thesis and in particular of the notion of "direct awareness."

Take the easy part first: the "external world" is what exists independent of the mind. Things can be external to one mind but not external to another mind: Boris Yeltsin's beliefs are external for me, but they are not external for Boris Yeltsin, because Yeltsin's beliefs are metaphysically independent of my mind, but they are not metaphysically independent of his mind. In general, what is external forS is what could (metaphysically) exist while S's mind did not. And we can call something "external" without qualification if it is external for everyone. There can be external objects (such as planets and sofas), in addition to external events, external states of affairs, external properties, and so on (fill in the "and so on" with whatever general sorts of things you believe exist). So what the direct realist holds is that there are some things of this very broad kind -- either external objects, or external events, or external states of affairs, etc. -- of which we are directly aware in perception.

The more difficult questions are, first, what is awareness, and second, what distinguishes direct awareness from indirect awareness. I won't attempt to provide exact definitions, in terms of necessary and sufficient conditions, on either of these counts, but some characterization of these notions short of that can nevertheless be illuminating.

1.1. Awareness in general

As I use the term, awareness is always awareness of something. And in my view, all of the general metaphysical categories of things that exist are kinds of things of which it is possible to be aware. That is, one can have awareness of objects ("substances" in the metaphysicians' sense), events, universals (if universals exist), tropes (if they exist), facts (if they exist), and so on. Of course, there might be some more specific classes of things of which we couldn't become aware for various non-philosophical reasons (e.g. parallel universes of which we can't become aware due to their inability to interact with our universe). The existence of such objects must, by the nature of the case, remain at best a matter of speculation.

Here are some examples of things that I'm presently aware of: There's a coffee cup on my desk, which I can see, and as a result, I am aware of the coffee cup (a substance). I am also aware of the color of the cup (a trope). If I pick up the cup, I can become aware of its motion (an event). I'm aware of a number of facts about the cup -- I'm aware that it's green (aware of the fact that it's green), I'm aware that it's a cup, and so on. I might also enjoy awareness of more exotic objects, if they exist. If universals exist, then I might have episodes of 'grasping' them, which would be episodes of awareness of the universals, though obviously a different kind of awareness. The same should be said for other abstract objects, such as sets, or propositions, or numbers.

Not all of my awareness is as direct as these examples, of course. I'm also aware of the fact that there are over a billion people in China (and so I am, albeit somewhat tenuously, aware of the people in China themselves), I'm aware of some of the properties of electrons, and I'm aware of the fact that the square on the hypotenuse of any right triangle equals the sum of the squares on the other two sides. These are all certainly cases of indirect awareness, though what that means we will have to discuss further below.

These examples also illustrate that there are different ways of being aware of something -- I can be aware of something by virtue of perceiving it, by virtue of intellectually grasping it (if it is an abstract object), or by virtue of making certain inferences, among other ways.

What can we say about the general nature of this phenomenon -- are there some things that all of these paradigmatic instances of awareness have in common? I think that in general, we can find the following three elements in any episode of awareness, namely, when S is aware of X,

(i) S has a certain kind of intentional (content-bearing) mental state;

(ii) X exists and at least roughly satisfies the content of the state; and

(iii) there is some kind of appropriate connection between X and the mental state, making it not merely accidental that S is enjoying a veridical mental state.

The intentional mental state we can call the state of awareness (of course, this means that in some cases, the state of awareness will be a state that might not have been awareness, if the other conditions hadn't been satisfied). The thing that S is aware of we can call the object of awareness, or the object of that mental state. And we can say a mental state is "veridical" if it has an (existent) object that satisfies its content, and "unveridical" otherwise. So all states of awareness are veridical (this is to say that "aware" is a success term), although there are some mental states that are otherwise like states of awareness but for being unveridical. A child who believes in Santa Claus is in a mental state that, to him, probably seems like being aware of Santa Claus. But of course, no one is actually aware of Santa Claus, because there is no such person to be aware of.

Notice that as a consequence of this characterization of awareness, as a mental state related in a certain way to its object, "aware of _______" (where the blank is to be filled in with some referring expression) is an extensional context (for if X stands in some relation to S, then X exists, and if X stands in some relation to S and X = Y, then Y stands in that relation to S). So if I'm aware of this coffee cup and this coffee cup is the 5000th plastic product produced at the Rubbermaid factory in Tacoma, then I'm aware of the 5000th plastic product produced at the Rubbermaid factory in Tacoma, even though I'm not aware that it is the 5000th plastic product produced at the Rubbermaid factory in Tacoma.

Two sorts of apparent counter-examples might be urged against this point and therefore against viewing awareness as a genuine relation between object and subject. The first sort would involve "awareness that ..." Let us suppose that this coffee cup is indeed the 5000th product of the Rubbermaid factory, etc., although I do not know this. Then I am aware that I am drinking from this cup, but I am not aware that I am drinking from the 5000th product of the Rubbermaid factory, etc. Does this show that "aware ..." creates an intensional context? No. What extensionality requires is that if one is aware of X, one is aware of Y whenever Y is identical with X. Now, being aware that I am drinking from this cup is being aware of the fact that I am drinking from this cup. But the fact that I am drinking from this cup is not identical with the fact that I am drinking from the 5000th product of the Rubbermaid factory, etc. So the move from "I am aware that I am drinking from this cup" to "I am aware that I am drinking from the 5000th product of the Rubbermaid factory, etc." does not represent a genuine substitution of identicals in the relevant sense. That is why the move is illegitimate. "aware of the fact that _______ is F" is intensional, even though "aware of _______" is extensional, because substitution of co-referring expressions into the context "the fact that _______ is F" does not guarantee reference to the same fact.

Another, possibly more convincing kind of case involves awareness of properties. Let's suppose that colors are spectral reflectance distributions, so that the color of an object is always identical with its spectral reflectance distribution. Now, I am aware of the color of this cup (the shade of green that it has). But we should at least hesitate to say that I am aware of its spectral reflectance distribution. At least, that doesn't seem like something that perception makes me aware of, even though perception does make me aware of the color of the cup. Does this show that "aware of _______" is an intensional context?

We have to be careful about the phrase "aware of the cup's spectral reflectance distribution." One natural reading of that is that it means aware of which spectral reflectance distribution the cup has, i.e. aware that it has such-and-such spectral reflectance distribution. (Compare: "I know Bill's phone number" means that I know which phone number Bill has, i.e. I know that he has phone number X, for some X.) This would be awareness of a fact. On this reading, I think it is clear that we do not (except perhaps for some scientists) enjoy awareness of the spectral reflectance distributions of the things around us. That is, we do not know what spectral reflectance distributions they have. And certainly we do not know this directly by perception. I think it is also clear that on this reading, we do normally enjoy awareness of the colors of things -- that is, we know which colors things have. But again, this is because, even if colors are identical with spectral reflectance distributions, the fact that an object has a certain color need not be identical with the fact that it has the corresponding spectral reflectance distribution. Notice that, on this reading of "I am aware of the cup's color," "the cup's color" is not being used to directly identify the object of awareness (despite surface appearances). Rather, it is being used to identify a certain determinable, about which the assertion is that I am aware of which determinate value falling under that determinable characterizes the cup. A similar case is "awareness whether": If I say, "I am aware of whether it has rained," I am not saying that there is an object called "whether it has rained" such that I'm aware of that object. Rather, I'm saying that I'm either aware that it has rained or aware that it has not.

The other reading of "aware of the cup's color" is that it is being used to attribute awareness of a trope (a property-instance), so that "the cup's color" really does refer to a certain entity of which I have awareness. But on this reading, I think it is much less clear that I don't have awareness of the cup's spectral reflectance distribution. If that's what colors are, then that is in fact what my visual system is detecting, and making me aware of. If one still wants to insist that I am not aware of objects' spectral reflectance distributions, in the sense of those particular property instances, then one should just reject this particular reductionist account of color.

That's enough to say about condition (ii). It will become clearer later, when we discuss perception in particular, why I say "roughly satisfies" (one can perceive a thing, and thereby be aware of it, while the thing does not exactly satisfy the content of your perceptual experience, but not if the thing's character is radically mismatched from the content of your experience).

The qualification, "a certain kind of," in (i) calls for some comment. Not just any intentional mental state is a candidate for awareness. Some kinds of intentional mental states cannot in principle be states of awareness, for reasons other than failure to satisfy conditions (ii) and (iii). For example, a state of believing that P is a candidate for constituting awareness of the fact that P. But a state of entertaining or wondering whether P is not even a candidate for constituting the awareness of the fact that P, regardless of whether it satisfies the other conditions -- a wondering-whether-P is an intentional mental state, and it might have an object that satisfies its content (namely, there might exist the fact that P), and it might even be appropriately connected with the fact that satisfies its content (depending on what kind of connection one requires -- at least there could be a reliable mechanism that leads to wondering-whether-P whenever P holds), but it still wouldn't be the awareness that P. And similarly, a state of imagining X is not a candidate for being the awareness of X, even if X exists, satisfies the content of the imagining, and is appropriately connected with the imagining (so it is non-accidental that I only imagine things that exist). If I am imagining Margaret Thatcher, I am not thereby aware of her. This is not to say, of course, that I may not be aware of her at the time (indeed, plausibly it is a precondition on my imagining her in particular that I be aware of her) -- I may indeed know that I am imagining a person who exists, and so be aware of Mrs. Thatcher, but my imagining can not constitute my awareness of her. My actual awareness is constituted by the various (true, justified, etc.) beliefs I have about her (or maybe just the belief that she exists), that I bring to mind as I form an image of her.

The only way I have of describing the relevant characteristic of mental states that qualifies them as candidates for being awarenesses -- the characteristic that both beliefs and perceptual experiences have but imaginings and wonderings-whether lack -- is a metaphor, but I think it nevertheless constitutes some clarification of the idea. It is this: certain mental states purport to represent reality. A belief 'purports' that reality satisfies its content, whereas a mere wondering does not. Again, we might say that a belief is 'assertive,' while a wondering-whether is 'neutral.' Likewise, perceptual experience is assertive (it purports to represent reality), while mere imaginings are not. But these metaphors also immediately invite certain misunderstandings that we must explicitly disavow. The metaphor of a belief's making some purport compares a belief to a person who makes an assertion or perhaps to the assertion that a person makes, and this immediately suggests the image of a speaker, a listener, and an utterance the speaker makes, all distinct from one another. But of course there are no such distinctions to be made with respect to beliefs -- there is no distinction between the 'assertion' that a belief makes and the belief itself, and there is no distinction analogous to the speaker/listener distinction. Because of the former point, it might be less misleading to say not that a belief makes a certain purport, but that the believer is purporting that reality is a certain way in having the belief, and likewise that I am purporting that reality is a certain way in having perceptual experience (which is not to say that in having perceptual experience I am believing that reality is a certain way; belief and perceptual experience are two different 'assertive' states). The only point of the metaphor is really this: there is a distinction between assertions and other, non-assertive speech acts (such as questions), and this is analogous to the distinction between beliefs and non-assertive propositional attitudes (such as wonderings-whether), and to the distinction between perceptual experiences and other non-assertive mental representations of particulars (namely, imaginings). The assertiveness of perceptual experience will call for further discussion below when we come to the analysis of perceptual experience.

We now turn to condition (iii), the connection between a state of awareness and its object. The need for this condition is shown by examples like the following:

(a) The case of veridical hallucination: suppose that excessive doses of LSD are causing me to hallucinate a spider crawling on my desk. As it happens, there is a spider crawling on my desk, but that isn't what is causing it to look to me as if there is a spider. It's the abnormal drugs in my brain that are causing me to have this experience (so the experience would be the same even if there weren't any spider). I think we have to allow the possibility of such cases -- whatever abnormal brain processes cause hallucinations could be going on and causing perception-like experiences while, by coincidence, there also existed in reality an object of the kind that the subject is hallucinating. In this case, I would not be aware of the spider on the desk (nor would I be seeing it), even though the spider would be satisfying the content of my experience.

(b) The lucky guess: suppose a gambler standing at the roulette wheel just 'feels' that the ball will land on black. He bets a lot of money on it, saying, "I just know it will land on black." It is generally agreed that this does not constitute his genuinely knowing that the ball will land on black (that is, assuming that he does not really possess psychic powers), and likewise it does not constitute his being aware of the fact that the ball will land on black. Of course, the gambler might get lucky -- the ball might in fact land on black. But he still was not aware that it was going to; he merely guessed and got lucky.

(c) The fortuitous leap of faith: Suppose that a number of people have come to believe, by a leap of faith, in an invisible unicorn that roams the surface of Mars. That is, these people have no cogent evidence of the existence of such a being, and have never had any contact with it, but they have chosen to believe in it by a sheer act of will (you may object to the notion of choosing to believe, but certainly there is some phenomenon called taking a 'leap of faith,' evidenced by some religious beliefs, so assume that that phenomenon is going on). It might happen, as chance would have it, that there really is an invisible unicorn roaming the surface of Mars. Still, their belief by virtue of faith does not constitute awareness of the unicorn, nor awareness of the fact that some such unicorn exists.

I assume that the reader has the same intuitions about these cases. These sorts of cases not only illustrate the need for condition (iii), but also suggest some ways of interpreting it, i.e. some appropriate kinds of 'connections.' In the first case, the natural analysis is that the veridicality of the experience is 'accidental,' or merely a matter of chance, because the thing that satisfies the content of the experience (the spider) does not cause the experience.

The second case differs in that a belief is involved. However, if one thinks of the gambler's feeling as an experience similar to perceptual experience, then it can seem that this case, too, is a case of veridical hallucination, in which case the causal analysis may seem appropriate here too -- or, better yet, an analysis in terms of reliability. The reliability analysis says that it is accidental that the gambler's belief is true because the sorts of feelings that he is relying on are not generally reliable. The reason I say the reliability analysis may be better than a causal analysis is that, since the gambler's belief is about the future, the thing that makes it true could not possibly cause the feeling that he has; yet we seem to have some sort of idea of what it would be to possess psychic powers in the form of precognition, such that one has to stipulate (in order to get the desired intuitive verdict) that the gambler in case (b) does not possess such powers. What it would be to possess precognition might be to possess some faculty that is reliable in producing the feeling that X is going to happen only when X is something that is really going to happen. The lucky gambler's problem is that he doesn't have such a faculty. This is why the feeling that the ball is going to land on black does not constitute awareness that the ball will land on black. The explanation of why the gambler's belief that the ball will land on black does not count as a state of awareness may simply be that his belief is based on the feeling, and the feeling is not a state of awareness.

Regardless of whether one views the gambler's feeling as analogous to a hallucination and accepts the above analysis, there is in addition, at least, a second reason why the gambler's belief is not a state of awareness. This is that it is epistemically irresponsible for the gambler to hold this belief (not to mention imprudent to bet on it -- and we regard it as foolish to bet on it because it is foolish to hold the belief). There is no reason, or no adequate reason, to think that the ball is going to land on black, and in the context of background knowledge that is available to any mentally competent adult in our society, it is highly unlikely that a given individual's feeling that a ball on a roulette wheel is going to land on black constitutes an extra-sensory perception. (Among other things, if ESP did exist, it would probably have been scientifically validated by now.) Because there is no good reason to think that the ball will land on black, it is a matter of chance that the gambler gets it right.

Case (c) lends itself best to a justification- or epistemic-responsibility-based analysis. That is, since the believers in this case clearly have no epistemic justification for thinking that there is an invisible unicorn on Mars, if they turn out to be right, then they're just lucky. But this case could also be analyzed in terms of reliability -- leaps of faith are not, in general, a reliable way of getting the truth.

One could also, at least in cases (a) and (c), appeal to a counter-factual analysis: what makes it accidental that my perceptual experience in case (a) is veridical is that I would have had the experience even if there were no spider on the table, and what makes the truth of the beliefs in case (c) accidental is that the subjects would have held those beliefs even if there were no invisible unicorn on Mars. (Case (b) is more problematic for this approach, since to apply this approach to case (b) would require one to evaluate a backtracking counter-factual.)

So we've seen four apparent ways of failing to satisfy condition (iii) on awareness: an intentional mental state can be accidentally veridical by reason of lacking justification (if the state is a belief), by lacking a causal connection with its object, by being unreliable (in the sense that states of this kind, or states produced in this manner, do not generally tend to be veridical), or by being such that the state would have occurred regardless of whether its content had been satisfied. I am not going to attempt to say which of these accounts is the correct account of the non-accidentality condition for awareness in general. That project, of course, is the generalized Gettier problem (generalized because it is the problem for awareness rather than just knowledge). I leave it open that different kinds of awareness might satisfy the non-accidentality condition in different ways, and I also leave it open that more than one of these versions of the condition might apply simultaneously. To illustrate what I mean by this, consider one of the things that I said I was aware of earlier. I am aware of the fact that there are over a billion people living in China. I am aware of this partly in virtue of my believing that there are over a billion people living in China. It is particularly plausible in this case that my belief, to constitute a state of awareness, needs to be epistemically justified (I need to have adequate reason for believing that there are over a billion people in China). Perhaps it also needs to be formed by a reliable method. Perhaps it also needs to be caused by the fact that there are over a billion people living in China. Or perhaps its just having one of these characteristics is sufficient (maybe there is a specific one that it needs to have, or maybe any of them will do). About all of that I remain noncommittal.

What I am interested in is two particular species of awareness: our episodes of perceiving our environment, and our perceptual knowledge of our environment -- that is to say, the awareness of our environment that, I claim, is constituted by our perceptual experiences, and the awareness of certain facts about our environment that is constituted by our perceptual beliefs. I will say below how I think the first kind of state satisfies the non-accidentality condition so as to qualify as awareness, and with regard to the latter state, I will explain how it satisfies what I take to be the most difficult version of the non-accidentality condition. It is not difficult to account for the reliability of our perceptual beliefs, nor for their causal connection to the facts that make them true, nor for their satisfaction of the counter-factual condition. Of the requirements that might plausibly be imposed for our perceptual beliefs to count as awareness, the one that it is most difficult to account for their satisfying (the one for which the rough account is not immediately obvious) is the requirement that they should be epistemically justified. So I will explain how I think perceptual beliefs do satisfy this requirement.

1.2. Awareness and knowledge

So far I've skirted the issue of the relationship between awareness and knowledge, though what I've said should make it clear that there is some close relation between knowledge of the kind epistemologists are usually interested in (i.e. propositional knowledge) and awareness. The relation, I maintain, is that of genus to species, with knowledge being the species. We can now see how knowledge exemplifies the general characteristics of awareness that I've identified above. In the case of knowledge, the state of awareness is a belief. The object of awareness is a fact corresponding to (satisfying) the propositional content of the belief -- i.e., if the content of the belief is that P, then the object of awareness is the fact that P. For a belief to be true is just for there to exist a fact corresponding to it in this sense, so my condition (ii) on awareness, as applied to belief, gives the truth condition for knowledge.

All of the versions of the non-accidentality condition that I made use of above were originally proposed by philosophers as conditions for knowledge -- I have simply generalized them. Where Nozick proposes that S knows that P only if, if P weren't true, S wouldn't believe that P, we can generalize this to: S is aware of X only if, if X didn't exist, S wouldn't be in the intentional state that he's in. Where the reliabilist says that S knows that P only if the mechanism by which S formed the belief that P is reliable (in the sense that it tends to produce mostly true beliefs), we could propose more generally that S is aware of X only if the mechanism that produced S's mental state whose object is X is reliable (in that it tends to produce mostly veridical states). It is straightforward how the causal account generalizes. Again, I do not mean to take a stand on any of these particular analyses of knowledge, and I don't even mean to imply that there must be a unique one of them that is correct for all kinds of knowledge.

The one analysis (or family of analyses) of non-accidentality that does not generalize is the analysis involving justification. From "S knows that P only if S is justified in believing that P," I can not generalize to a possible condition for awareness in general. The reason for this is that the notion of epistemic justification only applies to beliefs. Mental states other than beliefs can not be epistemically justified or unjustified (for example, if I am having a certain sensation, it doesn't make sense to ask whether I'm epistemically justified in having that sensation). What this means is just that we will have to use some other account of non-accidentality for non-belief forms of awareness (we will return to this point in chapter 2), but it may still be true that epistemic justification is a necessary condition on knowledge. One consequence of this point is that it is possible for a philosophical skeptic to argue that we lack knowledge about the external world, without denying that we have perceptual awareness of (i.e., perceive) the external world, on the ground that beliefs have to satisfy a more stringent requirement to count as awareness than perceptual experiences do.

We can summarize the relation between knowledge and awareness by saying simply that knowledge is the awareness of facts. So when I said that I am aware of the fact that there are over a billion people living in China, that was just to say that I know that there are over a billion people living in China.

1.3. Epistemic dependence

As I briefly mentioned above, sometimes states of awareness (or mental states that are candidates for awareness) are based on other states of awareness (or awareness candidates). Let's look at some examples of this relation before trying to characterize it in general:

(a) I believe that there are well over a billion people in China. Why do I believe this? Because earlier during the writing of this chapter, I looked up China in a recent almanac, and I then saw that the almanac listed for the population of China a number beginning with a 1 and a 2 and having ten digits. Upon seeing this, I believed that the almanac reported that the population of China was well over a billion. So my belief that China contains well over a billion people is based on the belief that the almanac reported that China contains well over a billion people. Since each of these beliefs do as a matter of fact constitute knowledge, we can also say: my knowledge that there are well over a billion people in China is based on my knowledge that the almanac reported that there were well over a billion people in China.

The based-on relation for beliefs is the most-discussed form of the relation among philosophers. The relation can also hold between non-belief intentional states, however:

(b) Return to my example of the gambler who believes that the ball on the roulette wheel will land on black. Why does he believe this? Because he has a feeling that it will. So his belief that the ball will land on black is based on his 'feeling' or hunch (scare quotes around "feeling" because it's not a feeling in the sense of either an emotion or a tactile sensation).

We can see that the feeling and the belief are two different states, because it would be possible for the feeling to exist without the belief -- for example, if the gambler were more reasonable, he might have the feeling that the ball will land on black but still doubt whether it will, because he might tell himself that he had no good reason to trust this feeling.

(c) When I converse with other people, I am to some extent aware of their emotional states, other than by their reporting those states. How am I aware of this? Well, in part because people have facial expressions and tones of voice that reflect their emotional states, and I perceive those expressions and tones of voice. So my awareness of their emotional states is based on my awareness of their facial expressions and certain tonal qualities in their voices.

This is not to say that my awareness of people's emotional states is based on beliefs about their facial expressions and tones of voice. In many cases I do not have the relevant beliefs at all, because I do not possess the concepts that would be required to classify complex tonal qualities and combinations of movements of facial features, and/or because I do not take notice of those properties. For example, I may sense that Sally is tired by hearing a certain quality in her voice -- call it tonal quality Q1. At the same time, I may not possess any concept for picking out Q1 and distinguishing it from other qualities. Furthermore, if I did possess such a concept, I might even then fail to believe that Sally's voice had Q1, despite my hearing that quality. In all probability, Q1 would be a very complex and subtle characteristic. The concepts required for identifying it might be complicated and abstract mathematical ones (like the concepts required for identifying a voiceprint), so that it would not be at all obvious at first glance that Sally's voice had Q1. Still, my hearing that quality might in fact be how I know when Sally is tired.

Nor need my awareness of other people's emotional states consist in beliefs either. We can show that my sensing of a person's emotional states is distinct from my beliefs about their emotional states by an argument parallel to the one used in (b) above -- namely, that it is possible for me to have the sense that another person is in a certain mental state without believing that they are. For example, suppose I believe (whether correctly or not) that the person I am observing is an actor. Suppose that this person is putting on a great show of grief. I may believe (or even know) that in fact he is not unhappy at all, while still feeling a strong impression of his unhappiness -- he seems unhappy.

What we have here are three examples of the 'basing' relation for states of awareness. In example (a), we have a belief based on another belief. In (b), there is a belief based upon a non-belief mental state. And in (c), there are non-belief mental states based on other non-belief mental states. We can make the following general observations about the relation:

(i) The based-on relation holds between mental states of the kind that are candidates for awareness.

This is partly a terminological point. Sometimes we speak of facts or other objects of awareness as bases for states of awareness. For instance, if asked to explain the basis for my belief that there are over a billion people in China, I may equally well say:

"My belief that there are over a billion people in China is based on the belief that the 1996 almanac reported that there were over a billion people in China," or

"My belief that there are over a billion people in China is based on the fact that the 1996 almanac reported that there were over a billion people in China," or

"My belief that there are over a billion people in China is based on the 1996 almanac's report."

Although all of these sound superficially as though they are identifying radically different things as standing in the same relation to the same belief, I think that they are merely notational variants. There is a certain relation that can hold between one mental state, A, and another mental state, B. When this relation holds, sometimes we describe the situation by saying that B is based on A, and sometimes we describe it (using "based on" in a slightly different sense) by saying that B is based on the thing that is the object of A. We can describe the relationship between these two senses of "based on" as follows: B is based on x in the second sense if and only if there is some mental state, A, such that B is based on A in the first sense, and x is the object of A.

Although these two ways of using the terminology are equally acceptable in standard English, it is necessary for our purposes to settle on one usage, so as to avoid confusion -- in a discussion of direct realism, it is particularly important to avoid any possible sources of confusion between mental states and their objects. I will therefore from here on out use "based on" only in the first sense -- that is, the sense which allows mental states to be based only on other mental states. This usage has one important advantage over the other usage: it allows us to characterize a relation that may hold between unveridical mental states. For example, suppose that Sam believes that he will have eternal life, (partly) because he believes that God has promised eternal life to all Christians. But suppose that Sam is mistaken -- God has not, in fact, made any such promise. Then it would be incorrect to say Sam's belief that he will have eternal life is based on the fact that God has promised eternal life to all Christians, or that it is based on God's promise to all Christians, because there is no such fact, and there is no such promise. We can only describe the situation if we adopt the first way of speaking and say that Sam's belief that he will have eternal life is based on his belief that God has promised, etc. (We could try instead speaking of the 'apparent fact' or 'ostensible fact' that God has promised eternal life to all Christians, but this seems like really just another way of referring to Sam's belief, since "apparent" would have to mean apparent to Sam, not apparent to the speaker.)

(ii) The basing relation is a form of epistemic dependence.

What I mean by this is that, when B is based on A, B's status as awareness depends on A's status as awareness. Intuitively, the basing relation is the relation whereby one mental state can transmit its favorable epistemic status to another mental state. If the first state doesn't have any favorable epistemic status (i.e. it doesn't count as awareness), then it can't transmit any (so the second state won't count as awareness). The 'favorable epistemic status' of a state of awareness amounts to its characteristics of being veridical and appropriately connected with its object, as discussed in section 1.1. So another way to put the point is this: If B is based on A, then B will count as awareness only if A is both veridical and appropriately connected with its object.

Thus, in light of the fact that my belief that there are over a billion people in China is based on my belief that the 1996 almanac reported that there were over a billion people in China, we can say that I know that there are over a billion people in China only if I not only believe but know that the 1996 almanac reported that there were over a billion people in China. If it turns out that my belief about the almanac was either false or unjustified (assuming this is my sole basis for my belief about the population of China), we would not say that I knew the population of China.(4)

We can say the same about example (b): given that the gambler's belief that the ball will land on black is based on a feeling, he knows that the ball will land on black only if the feeling constitutes awareness. If the gambler doesn't actually possess extrasensory powers (so the feeling is not genuine awareness), then he doesn't know (isn't aware) that the ball will land on black. And of course the same goes for cases like (c): if my perceptual experiences of people's facial expressions and voices are not genuine awarenesses (if they're hallucinatory), then I also will fail to be genuinely aware of their emotional states.

Notice that I have not said that, if B is based on A, then if A counts as awareness, B will count as awareness; I have only said that B will not count as awareness unless A does. I have only asserted a necessary condition for B's counting as awareness. There are two reasons why it would be a mistake to make the sufficiency claim: first, because A's being a state of awareness and B's being based on A are not sufficient to guarantee that B is veridical; and second, because even if B is based on A, A is a genuine state of awareness, and B is veridical, all this still is not sufficient for B to be non-accidentally veridical. Both points can be made using an example of Goldman's: Suppose that Henry is driving through an area where there are a lot of phony barns. These phony barns look just like real barns from the road, but in fact they are just façades, with no rear walls or interiors. Henry sees something that looks like a barn, and he believes that there is a barn there. We can now imagine two cases: First, suppose that the barn-like object is a barn façade. In that case, Henry is seeing (hence, is aware of) the barn façade. The barn façade roughly satisfies the content of Henry's visual experience (by having the right size, shape, location, and distribution of colors), and is appropriately connected with Henry's visual experience (by causing it in the normal way). Henry's visual experience is a state of awareness (albeit not the awareness of a barn), and his belief that there is a barn there is based on his visual experience, but his belief is not a state of awareness, because it is false. This sort of example can also be devised for beliefs arrived at through non-demonstrative inference.

Second, we can imagine that the barn-like object is a real barn, although there are plenty of barn façades in the vicinity, and if Henry were to see one of them, he would mistake it for a barn. In this case, Henry's visual experience is a state of awareness (he is aware of the barn), his belief that there is a barn there is based on it, and his belief is true, but his belief still does not amount to awareness, or knowledge, due to the possibility of there having been a barn façade present instead of a real barn.(5)

(iii) Inference is a special case of basing.

Just as knowledge is the form of awareness which is constituted by beliefs, inference is the form of the basing relation in which a belief is based on another belief -- that is, to infer Q from P is to base a belief that Q on a belief that P. This is illustrated in example (a). It is interesting that just as knowledge is the most-studied form of awareness in philosophy, inference is the most-studied form of the basing relation in philosophy.

(iv) When B is based on A, the content of A must be relevant to the content of B, such that the existence of something satisfying the actual content of A either entails or makes highly probable, or appears to the subject to entail or make highly probable, the existence of something satisfying the actual content of B.

This relation is most apparent in example (b), for the content of the gambler's feeling is the same as the content of his belief, so of course the existence of something satisfying the actual content of his feeling would guarantee that something satisfies the actual content of his belief. There is an equally strong connection in cases of deductive inferences -- i.e., when I deduce one belief from another, the content of the former is typically related to the content of the latter in such a way that if the latter is true, the former must be.

The "appears to the subject" clause is needed to account for cases in which a person commits a fallacy. In such a case, a person may base a belief that Q, for example, on a belief that P, even though in fact P does not entail or render probable Q. Still, P will at least appear to the subject to entail or render probable Q.

The beginning clause in my statement of (iv) about 'relevance' is not meant to be redundant. It is meant to account for the fact that one cannot, for example, base a belief in the four-color theorem on the belief that today is Tuesday -- even though, technically, one might say the fact that today is Tuesday guarantees (entails) that the four-color theorem is true. (In this sense, any proposition whatever guarantees that the four-color theorem is true, since the four-color theorem is necessarily true.) The relevance condition stipulates that the entailment must hold in virtue of the relevance between the contents of A and B.

The 'making probable' clause applies to both examples (a) and (c). That the almanac reports that there are over a billion people in China does not strictly guarantee that there are over a billion people in China, but it does make it highly probable, in the context of my background knowledge. Similarly, people's having certain facial expressions and tones of voice makes it highly probable that they have certain emotional states, given normal circumstances.

I characterized the probability relation differently for the two cases, and this is something that requires comment. In both cases, the probability relation was itself relative to something (i.e., something other than the mental state that the other state is based upon) -- in the first case, I said it was relative to background knowledge. In the latter case, I said it was relative to normal conditions. I think the motivation for the relativization in either case is clear enough. I don't want to say that, completely a priori, the fact that an almanac reports that the population of China is greater than a billion makes it highly probable that the population of China is greater than a billion. Abstracting from our background knowledge about almanacs, statistics-gathering practices in our society, and so on, I have no idea whether the existence of the almanac's report would confirm the proposition that it reports or not. Likewise, the occurrence of certain facial movements only makes it highly probable that a person is feeling anger in context of certain general but contingent facts about humans.

There is a rationale for relativizing in the first case to background knowledge and for not doing so in the second case. In the first case, we have inferential basing -- i.e., a belief based on another belief. The inferential basing relation needs to be able to transmit justification. That is, inference is a way (at least potentially, if everything goes right) of justifying a belief. But the existence of a probability relation between (the content of) belief B and a set of facts of which I (the believer) am entirely unaware would not contribute to the justification of B. B could, however, be rendered justified by being highly probable relative to another belief of mine and my background knowledge.

The same consideration does not apply to case (c). There is no requirement that non-inferential basings should transmit justification -- in fact, they cannot do so, because non-belief mental states are incapable of being either justified or unjustified. Furthermore, we should not make use of the notion of background knowledge in case (c), if we want to preserve that as an instance of awareness, because the relevant 'background facts' that make it highly probable that a person with certain facial expressions has certain emotions are likely to be unknown to me. What sort of facts would these be? Perhaps facts about the way human beings are generally 'wired up,' together with facts about the sort of conditions that usually obtain in our environment. I am, however, woefully ignorant of physiology (as are most people), and certainly don't know anything that would be adequate to underwrite the sort of probability relation in question. Or perhaps we should look to something simpler, such as the fact that people with facial expression F usually have emotion E. This too, I am afraid, is something I would be unaware of in many if not most cases. You might say, I know that smiles indicate happiness and frowns indicate unhappiness. But I know very little beyond that (and similar simplistic criteria), and this sort of principle is too crude and simple to do justice to my in-practice ability to distinguish a variety of different emotional states on the basis of facial expressions. I do not know what facial expression indicates tiredness, or annoyance, or what distinguishes a happy smile from a nervous smile. I am able to tell when a person is tired, or annoyed, etc., but I do not know how I do it. If someone were to propose to me that when people are tired, their eyes diverge slightly, and this is part of how we are able to tell when others are tired, I would have to say, "That may very well be; I do not know."

Because of these considerations, we should say that when B is based on A, if B is a belief, then the existence of something satisfying A makes probable the existence of something satisfying B, given background knowledge of the subject; and if B is not a belief, then the existence of something satisfying A makes probable the existence of something satisfying B, given normal conditions. We note that normal conditions are not necessarily conditions that the subject knows or believes to be normal, or even believes to obtain.

(v) Basing is a species of causal relation.

When B is based on A, A causes or causally sustains B, so that if the subject weren't in or hadn't been in state A, he wouldn't be in state B. This is clear in each of my examples:

(a) My belief that the almanac reports that there are over a billion people in China causes me to believe that there are over a billion people in China, and that is why, if I hadn't believed that the almanac reported that there were over a billion people in China, I wouldn't have believed that there were over a billion people in China. (In actual fact, my belief is also partly based on memory of statements I have heard from other people over the years. But we are pretending that my knowledge of the almanac report is my sole basis.)

(b) The gambler's feeling that the ball will land on black causes him to believe that the ball will land on black, and if he hadn't had the feeling, he wouldn't have had the belief.

(c) My seeing people's facial expressions and hearing their voices causes me to be aware of their emotional states. If I didn't see their facial expressions or hear their tones of voice, then I wouldn't be aware of their emotional states. (It is difficult to judge a person's mood from written correspondence precisely because much of our awareness of others' emotional states is based on awareness of their facial expressions and tones of voice. Of course, some of it is also based on what they say.)

We can appreciate the importance of condition (v) by considering cases where it fails. Here's a simple case involving beliefs: I'm in a math class, and the teacher informs me of the Pythagorean Theorem. This immediately causes me, let's suppose, to believe the Pythagorean Theorem, because I trust my teacher. There are in fact many different ways of proving the Theorem mathematically, though I do not know any of them (in the sense that I have not seen them worked out and could not produce any of them). Some of these ways involve only using certain simple arithmetical and geometrical premises which I do know. From a purely logical standpoint, it might be said that these items of knowledge that I have are grounds for the Pythagorean Theorem, and of course they are better grounds than the knowledge of a teacher's testimony. But I do not think anyone would say they are in fact my grounds for believing the Pythagorean Theorem, because the beliefs comprising them were not active in the process by which I formed my belief in the Pythagorean Theorem. My actual basis for belief is my belief that the teacher has said the Pythagorean Theorem is true.

(v) is also what distinguishes genuine reports of reasons for belief from rationalizations -- if a belief that P has not played any role in either producing or sustaining my belief that Q, then if I cite P as my reason for Q, even if I do happen to believe P and even if P is a good reason for Q, we call this "rationalizing."

Note that the causal connection is fundamental and necessary, and not the counter-factual connection. That is, the reason why most of the time, when B is based on A, B counterfactually depends on A is that whenever B is based on A, A causes B. It is possible to have a case in which B is based on A even though, if the subject hadn't been in state A, he would still have been in B -- just suppose that if S hadn't been in A, he would have been in some other cognitive state, C, which would have generated B instead (the case of the pre-empted cause). But it is not possible to have a case in which A is the basis for B while A plays no causal role in producing or sustaining B.

The causal condition is equally important in cases of basing not involving beliefs. Return to example (c). Suppose that research shows that when human beings get tired, a number of perceptible things happen to their faces. Let's suppose that their eyes diverge slightly and their lower lips sag just a little. And suppose we find that both of these changes are easily detectible to other humans' visual systems. It seems clear that, that much having been discovered, there remains an open question: which of these changes, if any (or both), is it the perception of which forms the basis for our sense that the person undergoing them is tired? The question seems to turn on which of the changes the perception of which plays a role in bringing about the perception of tiredness. It could be that we perceive the eye change but that it doesn't have anything to do with our sensing the person's emotions, for example.

We should be careful now about the difference between a cause and the cause of a state of awareness. It may turn out that there are several different states of awareness that contribute to sustaining state B. For example, there are by now many different causes of my belief in the Pythagorean Theorem -- I have heard it asserted or assumed by many different people and textbooks, I have seen a visual demonstration of it in a museum and another on a television program, and I've seen at least one or two proofs of it. Each of these experiences might be called a cause of my belief, though none of them is the cause, because none of them clearly stands out from the rest as the most important. Shall we say that my belief is based on one or more of these experiences? Well, none of these experiences is the basis for my belief, but my belief is partly based on each of them, and we can say that my belief is (without qualification) based on the totality of the experiences.

We might now worry about deviant causal chains. Observations (i), (iv) and (v) are each necessary for a state B to be based on A, but they are not sufficient, because of the problem of deviant causal chains. If we add in (ii), we might have a sufficient set of conditions, but (ii) isn't really one of the conditions on the basing relation in the same sense that (i), (iv), and (v) are -- once we've stated (ii), we can still wonder under what conditions B's epistemic status does depend on A's epistemic status, and the other conditions are supposed to answer that, at least partly.

Here is an example of a deviant causal chain: Return to my learning of the Pythagorean Theorem. Suppose that earlier in the year, this same teacher has taught me certain axioms of arithmetic and geometry. These axioms are propositions from which the Pythagorean Theorem follows, although just as before, I have not actually seen any of the proofs of the Theorem, and my belief is proximately caused by the teacher's testimony and based on my trust in his veracity. We have agreed that in this case, my belief in the Pythagorean Theorem is not based on the mentioned axioms of geometry and arithmetic. But now add this detail: suppose that the teacher would not have taught me the Pythagorean Theorem unless I had first demonstrated mastery of the material presented earlier in the course. He has very accurate testing techniques, and he never teaches the Pythagorean Theorem to anyone who has not first learned the axioms of arithmetic and geometry. Thus, my knowledge of the axioms of arithmetic and geometry has (indirectly) caused me to believe the Pythagorean Theorem, by causing the teacher to tell it to me. Still, my beliefs in the axioms are not the basis for my belief in the Pythagorean Theorem. My sheer trust in the teacher's veracity is.

We could equally well imagine that the teacher won't teach students the Pythagorean Theorem unless they have first mastered a history lesson, so my knowledge of history would cause me to believe the Pythagorean Theorem -- here the failure of the one belief to be based on the other is even clearer, if that's possible. But to return to the above case: Condition (v) is satisfied: my belief in the axioms causes (albeit indirectly) my belief in the Pythagorean Theorem, explaining why if I hadn't believed the axioms, I wouldn't have come to believe the Pythagorean Theorem. Condition (iv) is satisfied: the axioms are logically relevant to the Pythagorean Theorem and in fact entail it. Condition (i) is unproblematic: beliefs are candidates for awareness (in the shape of knowledge). We can even make a go at condition (ii): suppose that the teacher's testing techniques are very good at distinguishing genuine understanding from mere rote repetition, so that if I hadn't really known but merely believed the axioms, the teacher would not have proceeded with the later course material. Still, my belief in the axioms isn't the basis for my belief in the Pythagorean Theorem.

Here is why I said (ii) might give us a sufficient set of conditions: although it's true in a sense that in this case, my warrant for believing Q depends on my warrant for believing P (where Q is the Pythagorean Theorem and P is the appropriate conjunction of axioms), it can be argued that this is not the relevant sense of "dependence." The dependence involved in the case is causal dependence, whereas what (ii) intends is constitutive dependence. That is, what (ii) requires is not that my warrant for believing P causes me to get warrant for believing Q, but rather that my warrant for believing Q depends on my warrant for believing P in the sense that my warrant for believing Q partly consists in my having warrant for believing P. And intuitively, this 'consists in' relation does not hold in the case at hand. Now, that states the meaning of (ii) for the case of beliefs based on other beliefs (warrant being a property of beliefs). We can convert it into a general statement about awareness easily enough: just as epistemologists use "warrant" (following Plantinga) for the property that converts true belief into knowledge, we could introduce a term for the property that converts a veridical intentional state into awareness -- I have above referred to it as "connectedness," "non-accidentality," and "positive epistemic status." We can then say that when B is based on A, where A and B are any kind of awareness, B's positive epistemic status partly consists in A's positive epistemic status. Consider how this principle would apply to example (c): What makes my awareness of Sally's voice non-accidentally veridical (I mean what makes the veridicality non-accidental) is that my auditory experience as of Sally's voice is caused by Sally's voice. Now what makes my awareness of Sally's tiredness non-accidentally veridical is also, in part, the fact that my auditory experience as of Sally's voice is caused by Sally's voice -- if my auditory experience were a veridical hallucination, then I would not be being aware of Sally's emotional state. This is not because the fact that my auditory experience is caused by Sally's voice causes my veridical sense of Sally's tiredness to be appropriately connected with its object; it is rather that the fact that my auditory experience is caused by Sally's voice (and hence amounts to hearing her voice) partly constitutes the appropriate connection between Sally's tiredness and my sense of Sally's tiredness. The appropriate connection between A's sense of B's emotional state and B's actual emotional state partly consists in the fact that A is perceiving some of the physical features of B that manifest B's emotional state (as opposed to hallucinating them).

I'm not going to press this as a satisfying answer to the deviant-causal-chains problem because I think a genuine analysis of the basing relation would require an answer to the question, "Under what conditions, exactly, does the positive epistemic status of A partly constitute the positive epistemic status of B?" and I do not have an answer to that question, other than to cite conditions (iv) and (v) -- which we have seen are insufficient. We can get closer to a sufficient set of conditions by stipulating that the causal mechanism connecting A to B has to be internal to the subject's mind -- that rules out my case with the math teacher. But there could still be (increasingly farfetched) cases of internally deviant causal chains: suppose that when I learn the axioms of arithmetic and geometry, I am so pleased with my intellectual progress (at having learned such interesting truths), that I get into a mood of reckless intellectual self-confidence, in which I decide that the next proposition I think up will surely be true and important. As it happens, the next proposition that I think up is one that (unbeknownst to me) follows from these axioms -- the Pythagorean Theorem -- and I immediately endorse it. So my knowledge of the axioms of arithmetic and geometry causes me to accept the Pythagorean Theorem, and the axioms entail the theorem, but it isn't the case that my belief in the theorem is based on my knowledge of the axioms. Again, the latter beliefs don't cause the former belief in the right way.

I don't have an answer to this analytical problem, but nothing crucial turns on the exact analysis of deviancy in causal chains, and I also do not take the lack of such an analysis as an obstacle to accepting that cognitive basing is a kind of causal relation. Deviants crop up wherever causal relations are involved: for an action to be intentional, it must be caused by an intention in an appropriate way; for a person to perceive an object, the object must cause an experience in an appropriate way; for a person to knock over an object, the person must cause the object to fall in a certain sort of way; for a person to break a vase, he must cause the vase to break in a certain way. Deviant causal chains can appear in any of these cases -- there can even be cases of causing a vase to break without breaking the vase (suppose I hire Joe to throw the vase on the floor: have I then broken the vase?), although there is no doubt that some sort of causal analysis of "breaking" is correct.(6) The moral is that a problem of deviant causal chains is what we should expect (even) if a causal account of cognitive "basing" is correct.

1.4. Direct vs. indirect realism, at last

All of the above has been by way of putting us in a position to appreciate my definition of direct realism: direct realism is the thesis that perception constitutes direct awareness of the external world. That is: in perception, we are aware of certain parts or aspects of the external world, and our awareness of these things is not based on our awareness of anything that's not in the external world. In contrast, idealism holds that in perception, we are aware of some internal (mind-dependent) phenomena, and we are not aware of the external world, since (abstract objects aside) there is no external world to be aware of. And indirect realism holds that either in perception or as a result of perception, we are aware of the external world, but our awareness of the external world (abstract objects aside) is always based on our awareness of something internal.

The way I've just defined the distinction between direct and indirect realism is not the only way of doing so, of course. It's not the only reasonable way of drawing the distinction, and it's not the only way that has been used by writers on perception. Since "direct realism" is a philosophers' term of art, there isn't really any unique right way of defining it, but some ways are more useful than others (mainly by virtue of making the view designated by the term more interesting). So I propose to look at a few other ways of drawing the distinction to point out how they differ from mine:

(1) Direct realism is the view that in at least some cases, we directly perceive the external world, where the notion of directness should be understood causally. That is, according to direct realism, the causal link between an object and our perceptual experience of the object is direct, in the sense that there are no intermediate causes between the object and the experience.

There's no need to dwell on the impropriety of this definition for my purposes. The definition could be appropriate if one wants "direct realism" to designate a clearly unacceptable view (as perhaps the term "naive realism" is meant to imply), but not if one wants it to designate a view of perception that has actually been held by philosophers. The falsity of 'direct realism' in the above sense is hardly a recent or surprising discovery of science or philosophy. The role of the brain in producing (e.g.) visual experiences may be regarded as a relatively recent and perhaps surprising scientific discovery, but the rough role of light (i.e. that light must travel between the object perceived and our eyes in order for us to see) has been known at least for centuries (it is why you don't see things if you interpose an opaque object between them and your eyes), and it would be inconsistent with 'direct realism' construed in this way. But any view that can be refuted by the fact that you can't see objects through an opaque screen is not very interesting. (Granted, a bit more than that might be required, to show that the reason you can't see through an opaque screen is that it doesn't transmit light, but I think the point remains that this form of 'direct realism' isn't very interesting.)

On the other hand, we can also find ways of defining the direct/indirect distinction that make indirect realism too easy to refute, such as:

(2) Indirect realism is the view that we never really see, feel, taste, or otherwise perceive anything external, although we nevertheless know that some such things exist. Instead, we only truly see, feel, etc. sense-data or ideas in the mind. Direct realism is the view that we can perceive external objects or events.

This is the form of indirect realism that Berkeley, by and by, manages to saddle Hylas with:

Hyl. Properly and immediately nothing can be perceived but ideas. All material things therefore are in themselves insensible, and to be perceived only by their ideas.

Phil. Ideas then are sensible, and their archetypes or originals insensible.

Hyl. Right.

There is no need to recount all the fun that Philonous goes on to have from there.(7)

Again, I think this characterization of the distinction just makes it too obvious which view is correct. The indirect realist -- even a sense data theorist -- needn't be committed to saying that we see sense data, still less that we don't see physical objects (suppose that seeing X is being aware of X on the basis of one's awareness of a visual sense datum of X: then we don't see visual sense data, since we don't have visual sense data of visual sense data, and we do see physical objects, since we are aware of them on the basis of awareness of visual sense data of them). Whatever one's account of seeing is, it had better wind up that typical middle-sized dry goods, such as sofas and elephants, are visible -- and I'm inclined to insist, in addition, that it better not turn out that sensations or ideas in the mind are visible.

(3) Indirect realism is the view that, in the situations in which we normally say we believe that certain physical objects are present in our environment because we see or otherwise perceive them, we are actually inferring that such objects are present, from our beliefs about what internal states we are enjoying. Direct realism is the view that we typically form physical-object beliefs without inferring them from beliefs about our mental states.

This version of 'indirect realism' just gets the phenomenology of perception wrong, in a fairly obvious way. Introspection reveals that we normally don't go through processes of inferring when it comes to simple physical-object beliefs about our immediate environment. When I see a coffee cup in an everyday context, I do not think to myself, "I am now having a visual experience as of a coffee cup. It is highly probable that if I have a visual experience as of a coffee cup, then there is a coffee cup present. Therefore, (probably) there is a coffee cup here." Instead, when I see the cup I just straightaway take it for granted that there is a cup there. There are even some people (philosophers, mainly) who would deny that there are such things as 'visual experiences' (not that they would deny that we see things, but they would deny that seeing can be analyzed in terms of enjoying a mental state called a 'visual experience' -- see chapter 2 below), and yet these philosophers still know (by seeing) that there are physical objects around them. There are even more people who, while knowing lots of things about their physical environment, entertain no opinion about such things as visual experiences, perhaps not even having the concept 'visual experience,' or 'tactile experience,' etc. They just don't think about those things. Unless one is either a philosopher or a cognitive psychologist, one just doesn't have much occasion to form or apply such concepts. But again, a view that can be refuted by (approximately) the fact that you can see that there's a cup on the desk without having the concept of a visual experience, is not very interesting.

(4) Direct realism is the view that we are sometimes noninferentially justified in believing a proposition asserting the existence of a physical object.(8) Indirect realism is the view that we are sometimes inferentially justified in believing a proposition asserting the existence of a physical object, but we're never noninferentially justified in believing such a proposition.

This pair of definitions is reminiscent of (3), but not the same as (3), for this reason: According to Fumerton, the claim that S's justification for believing P is inferential does not entail that S's belief that P was actually the product of an inference; there is a derivative sense of inferential justification, having to do in part with a belief's being caused by an experience, such that a belief can be inferentially justified on the basis of an experience, without the belief having been inferred from anything.(9)

How does this formulation differ from mine? One difference is perhaps only verbal: Fumerton and I both agree that a belief might be based on some mental state that's not a belief (such as an experience), where this involves the mental state's causing the belief in an appropriate way. He calls this relationship a form of "inferential justification," while I reserve any term involving a cognate of "infer" for a relation between beliefs. But Fumerton may be using "on the basis of" in the way that I said I was not going to -- i.e., the possibility he allows may only be what I would express by saying that a belief can be based on beliefs about experiences.

Second, Fumerton's version of direct realism is about beliefs, while I have spoken more broadly of awareness. So my direct realist, unlike Fumerton's, is not committed to saying that there are any beliefs that aren't based on anything. Instead, he says that there are some states of awareness of the external world that aren't based on anything. Whether this includes beliefs is left open. Also, my indirect realist is not forced to posit an extra sense or extra form of "inferential justification" -- although he would have to posit other forms of 'basing' besides inferential basing.

My formulation is meant to retain the epistemological spirit of (3) and (4) while allowing the indirect realist (at least prima facie) to escape the obvious psychological objections to (3). On my formulation, the indirect realist must hold that when perceiving, people are in some manner aware of certain internal states or events, but the indirect realist need not hold that people believe these internal events are going on or have concepts of these internal events. The indirect realist also doesn't have to hold that any inferring is going on, though he does have to hold that our awareness of the external world is in some manner based on our awareness of the internal phenomena. My formulation is thus designed to give the epistemological indirect realist a break.

(5) Indirect realism is the view that we perceive external things at least in part by virtue of having certain internal mental states that 'represent' them, in the sense of having intentional contents that external things can satisfy or fail to satisfy. Direct realism is the view that people perceive things without having any such states.

It should be clear that this formulation is very different from my own, since on my conception of awareness, being aware of something always entails having a mental state with content, and yet I haven't said anything to imply that 'direct realism' is incompatible with our having awareness (as it would be on the present definition of "direct realism," if that conception of awareness is correct). If one describes such a mental state as a "representation," then being aware of something always involves having a mental representation. It should also be clear that it is not true, on my view, that being aware of something always involves being aware of a mental representation of that thing. For, given the conception of awareness at hand, to be aware of a mental representation would involve having a mental representation of a mental representation, and it is surely false that whenever S is aware of X, S has a mental representation of a mental representation of X. In fact, nothing I've said so far entails that anyone is ever aware of mental representations (except that I do, by talking about mental representations, at least imply that I am, presently, aware that they exist).

To make the issue clearer: according to formulation (5), the 'indirect realist' holds that there's a mental state such that (a) when you're perceiving a table (where "perceive" is a success term), you're in that state, (b) you perceive the table at least in part by virtue of being in that state, but (c) it is metaphysically possible for you to be in that state while there is no table. The 'direct realist,' under definition (5), holds that there is no such state; he says that the only mental state that you're in when perceiving a table, such that you perceive the table by being in that state, is a state of perceiving the table -- the things I've been calling "perceptual experiences" don't exist.(10) We'll discuss this kind of 'ultra-direct realism' further in chapter 2, where I'll give reasons for rejecting it.

(6) Direct realism holds that there are some external objects that we see, such that we don't see them in virtue of seeing anything else. Indirect realism holds that there are some mental objects that we see not in virtue of seeing anything else, and there are also some external objects that we see, but we always see external objects in virtue of seeing things distinct from them.(11)

This is Frank Jackson's formulation of the issue. One respect in which it differs from mine is that Jackson restricts his concern to visual perception, while I am concerned with perceptual awareness in general. Another difference is that Jackson commits the indirect realist to the view that we can sometimes see mental phenomena. Thus, consider the possible sense-data theorist mentioned above under (2), the one who holds that seeing X should be defined in terms of (among other things) having a visual sense-datum of X: on Jackson's formulation, this would actually be incompatible with indirect realism, because it implies that (given that we don't have visual sense data of any mental phenomena) we don't see any mental phenomena, and it implies that when we see physical objects, we sometimes don't see them in virtue of seeing anything else (given that we don't see any non-physical things). This apparent deficiency in the formulation could be remedied by replacing "see" with "apprehend" or "become aware of," thus: the direct realist maintains that we sometimes are aware of certain physical phenomena not in virtue of being aware of anything else; the indirect realist maintains that we're sometimes aware of certain mental phenomena not in virtue of being aware of anything else, and we're also sometimes aware of physical phenomena, but we're always aware of physical phenomena in virtue of being aware of other things (meaning: for each X such that X is physical and someone is aware of X, there exists a Y such that he's aware of X in virtue of being aware of Y. Y might be physical or non-physical).

More importantly, my formulation is closer to the epistemological concerns of (4) as a result of using the 'based on' relation rather than the 'in virtue of' relation. These relations are importantly different. My distinction between direct and indirect awareness stems from the observation that sometimes a mental state gets to count as awareness (in part) in virtue of being appropriately related to, including being appropriately caused by, another state of awareness. Jackson's distinction between mediate and immediate awareness (assuming he would allow the substitution of "be aware of" for "see") stems from the observation that sometimes a given mental state gets to count as the awareness of X (in part) in virtue of being the awareness of Y. So my 'basing' relation is a kind of causal dependence ("B is based on A" implies "A causes B"),(12) while Jackson's 'in virtue of' relation is a kind of constitutive dependence: "S s in virtue of ing" is more like "S's ing counts as (or constitutes) S's ing" than like "S's ing causes S's ing." This comes out in his definitions of "in virtue of":

An A is F in virtue of a B being F if the application of "---- is F" to an A is definable in terms of its application to a B and a relation, R, between As and Bs, but not conversely.

This A is F in virtue of this B being F if (i) an A is F in virtue of a B being F (as just defined), (ii) this A and this B are F, and (iii) this A and this B bear R to each other.(13)

Huemer’s Theory of Perception: Analysis and Objections

By Ethan Rubin

In his book Skepticism and the Veil of Perception, Michael Huemer lays out an account of perception that supports a version of direct realism. He states two main theses: that perception is direct awareness of external reality, and that it leads to non-inferential knowledge of that reality. The second claim requires that the first be adequately defended, which is the goal of Chapter IV in particular. In this paper, I intend to map out Huemer’s argument and assess its strengths and weaknesses; each section explaining a key point in his theory. After it has been explained, I will bring up objections to certain aspects of the theory as they appear in the text, and consider the most promising defenses against them.

Awareness requires an apprehension and a non-accidental correspondence between apprehension and object

Huemer’s first task is to clarify his claim regarding direct awareness. He uses the term “awareness” in a technical sense, as the relation between one who is aware and the object of which he is aware. This establishes that one must be aware of something – if there is no object present, then there cannot be actual awareness. This excludes cases of hallucination from awareness.
Huemer claims that awareness must include a state of apprehension. He defines this term as a mental state of assertive representation. Not all mental states, he claims, have representational content (the example he uses is the sensation of tickling). Thoughts, desires, and perceptions, however, do have representation content, but represent their objects in different ways. Apprehensions are characterized by actualized representation, meaning that they represent their objects as being the case. He calls this characteristic the apprehension’s assertiveness. Apprehension, therefore, must represent an object as actually existing, as opposed to representing it as a possibility or command.
Huemer also requires that the apprehension of an object at least roughly correspond to the nature of the object. He calls this “satisfying the content of the representation”. By accepting the possibility of some deviation, he allows for certain common illusions, such as the appearance of a bent stick in the water. The correspondence between the awareness of the stick and the stick itself is close enough that the viewer can correctly identify it and describe it with reasonable accuracy. If the stick were perceived as a different object, such as a green kitten, there would not be enough correspondence between the apprehension and its object to consider the relationship awareness.
Huemer also stipulates that the correspondence between apprehension and its object cannot be accidental, stating that “the apprehension must have been formed in such a way, and under such conditions, as to make its correspondence with reality probable”. For instance, if one were to hallucinate a particular scene while that scene coincidentally occurs elsewhere, he or she cannot be said to be aware of that event. Note that this scenario is unsatisfactory even if the correspondence is perfect. This sort of example highlights two problems with accidental correspondence: the apprehension is not of the true object, and the observer does not have sufficient reasons to believe that it is.

Direct awareness is unmediated

Huemer’s theory hinges on the difference between direct and indirect awareness. In indirect awareness, he states, one’s awareness is of x, but only by means of his awareness of something else. When driving a car, for instance, one is aware of the amount of gas left in the tank. This awareness is indirect because it is based on the driver’s awareness of the indicator needle on the dashboard, which he or she expects to reflect the amount of gas in the tank. Direct awareness, by contrast, is unmediated by such a secondary awareness. In order to be indirectly aware of something, one must first have a direct awareness of something else. Indirect awareness is a causal and logical relationship – one is led to reach the second awareness by a logical connection between it and the first. As such, it transmits the authority of the direct awareness to the indirect. This requires that direct awareness refer reliably to external reality.
Three Elements of Perception: a Perceptual Experience, an Object of Perception and a Causal Relationship

Having laid the foundation for his theory, Huemer turns to an analysis of perception. He identifies three major components of perception, each structured similarly to awareness. First, there is a purely internal mental state, which he calls the perceptual experience. Second, there is an object of perception, which is external and at least roughly satisfies the content of the experience. Third, there is a causal relationship between the two. The absence of any of these elements disqualifies the event in question from being perception.
The perceptual experience differs from perception as a whole in that it does not necessarily entail an external object. Because the experience is internal, it is not necessary that it be accompanied by an object. This is how Huemer accounts for hallucination. A perceptual experience does occur in hallucination, but there is no external object present. The perceptual experience still occurs because on an internal level, hallucinations are indistinguishable from genuine perception. This implies that they share a common mental state and that internal experiences should be recognized as separate from external objects of perception.
As in awareness, the object of perception must meet a standard of resemblance to the content of the perceptual experience. This standard allows for some discrepancies, but only to a point: when the experience represents the object as being fundamentally different than it is in reality, it can no longer be called perception. The content satisfaction criterion is present in other representations as well. A painting, for example, can diverge from its subject’s appearance to a certain extent, but at some point it can no longer be considered a painting of that subject.
Huemer recognizes another sort of perceptual error that must be explained. It is possible to perceive an object in a manner that corresponds to the actual nature of the object and still mistake it for something other than it is. For instance, one might see a coil of rope and mistake it for a snake. To resolve this, Huemer introduces the notion of primary versus secondary perception. In secondary perception, the object is perceived by virtue of another perception: perceiving the coil of rope or the snake involves the same primary perception, as the same image is seen in both cases. The difference lies in the secondary perception, in which that same image is taken to be of different objects. The coil of rope is therefore seen as a snake. This sort of error is only admissible to a point, much like the case of illusion in primary perceptions. A mistaken secondary perception only arises from a primary perception that has a reasonable resemblance to the secondary perception; a coil of rope does have some visual resemblance to a snake. If someone were to mistake the coil of rope for a bear, there is a more serious error at work.
Finally, there must be a connection between the internal experience and the external object. Huemer proposes that the object must have caused the perceptual experience if the experience is of the object, thereby excluding coincidental correspondence. This causal relationship also must be direct; Huemer excludes what he calls deviant causal chains. If you were to have an accurate perceptual experience, but only because someone with the appropriate knowledge implanted the perception in your mind, it is true in a sense that the presence of the object caused the perceptual experience. The causal chain, however, has an intermediary link and is not perception.

Three Elements of Perceptual Experience: Sensory Qualia, Representational Content and Forcefulness

Huemer proceeds to subdivide the first component of perception, perceptual experience, into three features. He claims that a perceptual experience always has sensory qualia, which are defined as “what it is like” to have the experience. It also must have representational content, and that content must have forcefulness – the characteristic of seeming present and real. These components are notably similar to those of awareness.
According to Huemer, all experiences are accompanied by qualia; sensory qualia are those that correspond to perceptual experiences, as opposed to emotional or imaginative experiences. Qualia exist over and above representational contents, and are ineffable in that they cannot be explained to someone who has never had a comparable experience. Someone who was born deaf, for example, cannot understand what it is like to hear. This ineffability is not mystical or metaphysical, nor does it apply to common experiences and normal perceivers – two people with unimpaired hearing can describe sounds to each other effectively.
On Huemer’s theory, perceptual experiences also involve representational content. He explains that “things appearing to be a certain way is not some further consequence of your experience; things appear a certain way by virtue of your having the perceptual experience itself”. This assertion challenges theories of perception that ascribe appearances to an act of interpretation that takes place after the perceptual experience. For Huemer, representational content is an essential part of the experience. Consider the bent stick illusion: the stick is not interpreted as being bent. On the contrary, the experience represents it as being bent and the viewer interprets this appearance as an illusion. If interpretation determined the object’s appearance, the illusion would only occur if the perceiver believes the stick is bent. But no normal perceiver would argue that the stick is bent, despite the fact that it appears to be so. The temptation to say the stick is bent is based on how the stick looks. Hence, this appearance must be an integral part of perceptual experience and independent from interpretation.
Representational content is crucial to learning because it represents the object of perception as something that actually exists. This evokes Huemer’s description of assertiveness – a perceptual experience represents its content as actualized, or as being the case. It follows is that representational content is propositional. A perceptual experience expresses the proposition “it is true that object X is before me,” which is a precondition for reaching conclusions regarding that object. This proposition leans on another, namely that “it is true that my perceptual experience portrays the external world with satisfactory accuracy.”
Huemer is careful to point out, however, that propositional content does not necessarily imply conceptual content. Conceptual content, unlike representational content, is not an intrinsic property of an experience. A perception is the same whether the perceiver has concepts for all the objects, for only some of them, or for none at all. In fact, we cannot have enough concepts to address the nuance and variability of experience. For example, the concept “red” is insufficient to differentiate between the many shades of red that we perceive as being distinct. The use of demonstratives can address them because it has a pointing function, saying “I see it is that, or thus and so.” This pointing does have propositional content, i.e. “it is true that I am perceiving that object, which is that way,” but the perceiver does not have concepts for “that object” or “that way.”
By rejecting the necessity of conceptual content, Huemer is not rejecting the possibility of conceptual content. He agrees that conceptual content exists and is capable of affecting perceptual experience. His point is that perceptual experiences can occur without conceptual content, implying that conceptual content is not an intrinsic or essential component of perception. He refers here to Wittgenstein’s ambiguous “duck-rabbit”. He admits that if one has the concepts of duck and of rabbit, the picture has the conceptual content of both duck and rabbit. If one only has the concept of duck, however, the picture will not have the conceptual content of rabbit. If the viewer does not have either concept, the picture has no conceptual content, but the viewer still has a perceptual experience. Perceptual experience can be altered by the inclusion of concepts, but it does not have to be conceptualized and does not depend on conceptual content.
The propositional, assertive nature of perceptual experience leads Huemer to his discussion of forcefulness. He begins by asking how imagining and perceiving differ. The two can have the same content – if one imagines a duck or sees one, the content is a duck in both cases. One possible difference is that a perceptual experience has more detail and precision than an imaginative one, but this difference can be overcome by focus and training, or by a photographic memory. Detail, therefore, cannot be the fundamental distinguishing factor between the two. No one confuses imagining with perceiving, because the latter represents its content as being actualized, whereas the former does not. Huemer calls this difference forcefulness. This should not be confused with Hume’s concept of vivacity, which is more like the difference in detail that Huemer considers and discards. Hume’s vivacity is merely a question of faintness or vividness, while Huemer’s forcefulness contains an element of being present.

Why This Is Direct Realism

One could support the majority of Huemer’s claims and still be a proponent of indirect realism by arguing that perception makes us aware of mental states that become knowledge by a secondary, non-perceptual process. Huemer, however, insists that we are directly aware of more than just mental states and that his theory of perception satisfies his definition of direct awareness. As he explained earlier, awareness consists of an apprehension, or assertive mental representation. His description of perceptual experiences accords with the definition of apprehension: perceptual experiences have forcefulness (making them assertive), qualia (making them mental) and representational content.
Huemer’s theory fits the definition of direct awareness by stipulating a causal connection between the perceptual experience and the object of perception. Saying that awareness must be of something is equivalent to saying that it must be caused by its object. Therefore, asking what a perception is awareness of is also asking what causes the perceptual experience. Huemer maintains that only physical facts can satisfy the contents of perception and therefore must be their source. It makes no sense to say that mental states cause perceptual experiences because the contents of perceptual experiences are not present in mental states; mental states do not have the properties, such as shape, color and texture, which form the contents of perceptual experiences. He rejects brain states for the same reason; normal perceivers do not have the perceptual experience of synapses firing. Perceptual experience cannot be caused by mental or brain states because they do not bear resemblance to its contents. The visual (or auditory, olfactory, etc.) experience is first and foremost of the object one is experiencing.
Based on these arguments, Huemer concludes that perceptual experiences are directly caused by physical objects that have the attributes that the experience represents them as having. According to Huemer, it follows that “In the primary sense of ‘aware’…we are directly aware of the fact that there are objects with those colors and shapes”. That is, because our perceptual experiences are direct, the knowledge we gain from them is also direct. He attributes the opposing argument, which holds that knowledge of external objects is indirect because it is based on perceptual experiences, to a confusion between the object of awareness and the vehicle of awareness. This is clarified by the following analogy: one must use an axe to chop wood. He is not, however, chopping the axe, but is chopping the wood by using the axe – the wood is the object of the chopping and the axe is the vehicle, or means, of the chopping. Applying this to perception, the perceptual experience is the metaphorical axe that “chops” external objects. We cannot perceive an object without having a perceptual experience that represents it to us, but that experience is only a tool. The awareness is directly of the objects by means of perception, just as wood is chopped by the man using the axe.
To put it another way, we do not perceive our perceptual experiences. If awareness were based on perceptual experience, we would have awareness of external objects by perceiving experiences, but this is not the case. We perceive external objects by having perceptual experiences, not by perceiving perceptual experiences. The same goes for awareness: our awareness does not arise from being aware of an apprehension, but simply by having an apprehension. Perceiving perceptual experience or being aware of apprehensions requires a second order act in which one turns his attention to processes that occur whether or not he reflects on them. This is an extra step, requiring introspection and deliberate effort, not a constitutive element of perception.

Objection 1: How to Recognize Knowledge

Huemer fails to account for a practical problem in his theory. He admits that one must be capable of handling certain mishaps that tend to befall perception from time to time, but does not make any conclusive statements about how this is to be done. Hallucination and correctness by coincidence are problems that he needs to address more thoroughly.
His definition of awareness stipulates that it is a relationship and therefore must be of something. This condition excludes hallucination from awareness because one cannot have a relationship with something that does not exist. There is an obvious external difference between awareness and hallucination that makes them fundamentally distinct, but this does not suit Huemer’s project. Since he is describing awareness phenomenologically, from the inside, he must account for how the perceiver himself understands his mental states. It makes sense to say that one cannot have a relation with a nonexistent object, but if he feels like he is in a state of awareness and cannot differentiate between his hallucination and a real object, it is unclear how the distinction is salient.
Huemer does admit that there is some irregularity in perception. His position is that we have knowledge via perception, which is not the same as saying that all perceptual experiences constitute knowledge. Even so, the fact that we cannot tell the difference between awareness and hallucination is problematic because it impedes knowing which experiences lead to knowledge. Huemer could argue that one is inclined to judge that an experience is hallucinatory when it does not accord with his expectations of reality, correcting for errors in perception after the fact, but this raises two problems. First, it is only a plausible solution if the hallucination is recognizably outlandish and depicts an “object” whose existence is improbable enough to make the hallucinator disregard his perceptual experience – remember that the mental state is the same in both perception and hallucination, the only difference being the presence or absence of the object. It is not implausible that one could have a mundane hallucination of an unsurprising object, or even an existing object that he had accurately perceived before. There would be no cause for suspicion and he would accept the hallucination as awareness. Second, inserting an act of judgment in the case of hallucination would leave Huemer open to the objection that such an act of judgment takes place in other cases as well. The mental state involved in hallucination is the same as that involved in perception – if hallucination is subject to review over and above the experience itself, normal perception must be subject to the same process of judgment. The inclusion of judgment in this context begins to stray dangerously close to indirect realism, which Huemer wants to avoid.
Similar arguments can be made regarding Huemer’s demand for a direct causal connection between apprehension or perceptual experience and the object represented. The distinction he makes between an acceptable connection and an accidental or deviant one is once again external rather than internal. One example he uses of accidental correctness is that of calling a friend. *After the phone rings multiple times, one may conclude that the friend is not home. However, one could unknowingly have dialed the wrong number and not actually tested whether the friend was home or not. The conclusion may still be correct by coincidence and, by asking the friend whether he was home at the time, he can come to know that his conclusion was correct, and yet this does not qualify as awareness. The reasons why it cannot be awareness are clear to the third party reading the example, but the person in the example has no access to those reasons. There is no way for him to verify the relationship between his experience and his apparent knowledge.
A deviant causal chain presents the same problem. In Huemer’s example, someone has a perceptual experience of a cup. A scientist has implanted an exact copy of the perceptual experience caused by the cup in the would-be observer’s brain, with the result that the experience does correspond with the object it represents. The cup caused a perceptual experience in that it caused the scientist to implant that specific experience, but the subject cannot be said to have perceived the cup because the causal connection is too far removed. The reader has no trouble understanding why this is not perception, but the deceived character in the example cannot reach the same understanding. In light of these examples, causal connection seems like a dubious criterion. If one cannot distinguish between the causal chain of a genuine apprehension and that of an “apprehension” based on coincidence or deception, then one cannot use causal connection as a standard for accepting or rejecting his own experiences. It seems that Huemer owes us a better solution to the internal problems of recognizing knowledge.

Objection 2: Where to Draw the Lines

Huemer is satisfied with some ambiguities that should make the reader wary. By making provisions for rough correspondence between a perceptual experience and its object but disqualifying those that do not correspond enough, he commits himself to a spectrum that covers the entire range between exact resemblance and complete disjunction. At some point in this spectrum, experience ceases to be perception and becomes hallucination. Most readers would ask Huemer to indicate where this point lies. It is easy to make an absurd example that highlights the difference between the extremes – compare seeing a stick in water that appears bent and seeing a stick in the water that appears to be a green kitten. The closer we come to the middle of the spectrum, however, the more difficult it is to distinguish – compare seeing a stick in water that appears bent and seeing a stick in water that appears slightly more bent than the optical phenomenon accounts for. How much more bent can the stick appear before one is no longer perceiving the stick?
Huemer might respond that the spectrum is ambiguous by nature and that distinctions must address the case at hand and its context. This may be true, but there must be some general standard in place by which to make the distinctions in each case. Even if it highlights a vague section of the spectrum as the area in which experience begins to lose legitimacy, there should be some kind of criterion. Saying that acceptable cases “roughly satisfy” the representation and unacceptable ones “diverge radically” tells us very little about what qualifies and what does not. Despite the intrinsic fuzziness of the correspondence condition, Huemer could stand to do a better job of defining the spectrum and identifying the boundaries of perception.
He falls prey to the same pitfall in describing the deviant causal chain. He states that the causal connection between perceptual experience and its object must be close enough that the object directly causes the experience, but “directly” does not specify what qualifies. I had to suppress laughter upon reading the sentence, “I shan’t enter into the question of how exactly one might define ‘deviant causal chain’….” Huemer identifies direct causal connection as an essential component of perception, in whose absence perception cannot occur at all. A deviant causal chain precludes direct causal connection, meaning that the experience in question is not perception. Seeing as this is central to his theory, how can Huemer justify glossing over what a deviant causal chain is? He is obligated to specify what is deviant and what is direct – saying that the deviant chain is “convoluted and abnormal” replaces “deviant” with synonyms and does nothing to pin down what it means.
This problem could also be addressed by appealing to case-by-case decisions. For the most part, what Huemer means by a deviant causal chain is understood despite the absence of a precise definition. The objection incites a sort of Wittgensteinian reply, as in “you know what I mean, this is perfectly clear to you when the case arises.” This solution works better here than it would for the previous objection. The resemblance condition must allow for a range of illusions and imprecisions, whereas the causal connection is a stricter requirement. The presence of virtually any intermediate cause between the experience and its object is sufficient to disqualify the causal chain, which makes it much easier to consider a case and decide that the relationship is not direct.

Objection 3: Unnecessary Components of Perceptual Experience

Huemer’s analysis of perceptual experience does a good job of analyzing the various features that are present, but his insistence that they are separate entities may be misled. He claims that sensory qualia, representational content and forcefulness are all different components of a perceptual experience. Upon consideration, however, it seems that they are inextricably linked and cannot be disjoined. Rather than split up perceptual experience into three elements, it would be more accurate to speak of it as a single entity with features that account for its particular nature. Forcefulness, for instance, can be considered an element of representational content, as it is essential to and inseparable from perceptual experience. Without forcefulness, the experience is no longer a perceptual one: it is an imagination or a memory. This is because forcefulness is a feature of how the object of perception is represented to the perceiver, namely as being present. But Huemer had posited assertiveness long before he introduced forcefulness. Assertiveness is an essential aspect of representational content and lends immediacy to experience; seeing as assertiveness does the same work as forcefulness, there is no reason to tack forcefulness onto the end of the theory.
Sensory qualia are the most dubious of the components Huemer identifies. He begins his discussion with the disclaimer that their ineffability is not mysterious and must not be mistaken for “a resort to obscurantism and mysticism”. This is not, however, the strongest objection against qualia. Even having accepted their ineffability as a characteristic of experience, the existence of qualia still seems superfluous. Because perceptual experiences are internal, as Huemer states, qualia could just as easily be an intrinsic characteristic of perceptual experiences without being a separate class of mental entities.
Huemer’s point is that the representational content and the object that satisfies it are the same, but because there is some difference between the object and the experience, some “what it is like” to experience the object, qualia must exist. The function he attributes to qualia, however, can easily be included in the notion of representational content. Representational content represents an object as being a certain way to the perceiver. This is an aspect of his internal mental state and as such has the same ineffability as qualia; it represents the object as being “this way.” As it represents the object to the perceiver, the perceiver experiences the representational content. How is this different from qualia, “what it is like” to perceive an object? The distinction implies that representational content is a component of perceptual experience that is not experienced in any particular way, which is absurd – “what it is like” for one to have a perceptual experience is what it is like to have its object represented to him. How else could representational content possibly function? There is no way that content could be represented to the perceiver except by his experiencing it, nor is there anything outside of his experience that he is aware of when he perceives something. The nature of representational content thus neutralizes the need for qualia to explain experience.
Huemer’s explanation of the difference between red and red* (the quale) is based on a confusion. He states that “…red* is a property of experience, whereas red … is a property of physical objects”. It is correct to separate these as properties of two different types, but the way in which he speaks of them is misleading. Red as a property of physical objects is not a color, but rather the tendency to reflect certain wavelengths of light. Color, on the other hand, is an experienced property. It would be more logical for red* to refer to the physical property of reflecting light and for red to indicate the color that is experienced. From this perspective, it is unnecessary to posit the existence of qualia because we no longer have the sense that the color we experience is something strange and illegitimate that must be explained away.
Upon asking whether there is any reason for qualia to exist or if they serve any purpose, Huemer exhibits more unintentional humor by responding “I do not know the answer to this”, yet still insisting that they must exist. He offers two potential answers, neither of which is very convincing. First, he claims that the information obtained through perceptual experiences could not be represented without qualia. The very fact that he uses the word “represented” betrays his argument. He asks how we could perceive red without qualia and swiftly concludes that it is impossible, but it is perfectly plausible that we perceive red by way of representational content, which represents the object as being red, and therefore have no reason to posit qualia. Second, he asserts that qualia serve a conative function, expressing the pain or pleasure of an experience. There is no obvious reason why representational content should not perform this function as well, representing a warm experience as pleasant or a red experience as striking. He argues that qualia “simultaneously give us information about the world and give us emotional reactions or desires. Those two functions are integrated into the same experience, rather than being functions of two separate states or events”. It is the purpose of representational content to give us information about the world; if the two functions are integrated, it makes more sense to simply assign them to representational content and discard qualia as redundant.

Objection 4: Sense Data and Representationalism

When he explains how his theory is a form of direct realism, Huemer makes a dangerous statement: “We might also be said to be aware (directly and primarily) of the colors and shapes of the (facing surfaces of) physical objects around us, since that could also be described as what satisfies the content of a state representing there to be objects of those colors and shapes”. Although he describes this view as if it were only a trivial variation of his previous claim, it opens the door to a host of opposing theories that he wants to avoid. In particular, it allows for the possibility of a sense datum theory, which in turn implies representationalism.
He ends this section by saying “We must therefore conclude that direct realism is true”. This conclusion follows from his original claim that we are directly aware of the existence of objects, but it does not follow from the sense datum theory he implies in his second claim. According to the latter theory, we are directly aware of sense data, not objects. In order to have awareness of objects, one must undergo a non-perceptual process of judgment, forming a theory that infers the existence of objects from the sense data. Therefore, sense data do “satisfy the content of a state representing there to be objects”, but they do not do so directly because the state is based on the sense data. By admitting the plausibility of this view, Huemer is in danger of committing himself to indirect realism.
The axe and wood analogy Huemer provides is clever and useful, but it does not grant him immunity from sense datum theory either. He intends the physical objects to be the “wood” and perceptual experience the “axe”, but the analogy works equally well if we replace “physical objects” with “sense data.” The argument would go as follows: We use perceptual experience as a tool that enables us to perceive sense data directly. As a consequence, we are aware of physical objects only indirectly. Huemer could object that sense data are also vehicles of perception, but his analogy betrays him again. If perceptual experience is the vehicle of perception, sense data must be the objects of perception. Once the sense data have been perceived, the analogy repeats: sense data become the vehicle by which we become aware of physical objects. At this point, however, awareness has already become indirect. In order to use them as means, one must first obtain the sense data as objects. When used as means, they are not vehicles of perception but rather of judgment – all the necessary perception has already occurred. Physical facts, in turn, become the objects of judgment and are thus distanced from the direct relationship with perception that Huemer wants to maintain.


For the most part, Huemer’s theory is plausible and supports his theses. Objections one through three do have some validity but are not strong enough to falsify his system in general. Some can be defended against, while others can be reconciled to his account with only minor revisions. Of the first three, objection three is the most radical, but Huemer could address it easily. Neither the existence of qualia nor the independence of forcefulness is so central to his argument that his theory would be irreparably damaged by removing them, and all the phenomena they explain could be preserved in the updated account.
Objection four, if correct, deals a heavy blow to Huemer’s original theses. Sense datum theory would rewrite his first thesis to say that perception is direct awareness of sense data. The second thesis would then have to be revised to say that we have indirect, inferential knowledge of the external world as a result of the sense data gathered by perception. Although Huemer only becomes explicitly vulnerable to sense datum theory at the end of the chapter, the rest of his account would not need extensive alteration to accommodate sense data.
If we replace his references to physical objects with references to sense data, we arrive at the following theory: perception consists of an internal mental state, an object that produces sense data in the perceiver, and a causal relationship between the mental state and the sense data. The internal mental state consists of the experiences of perceiving sense data (whether or not these are called qualia), whose contents represent patches of color as immediately present (whether or not this is called forcefulness). Therefore, perception is direct awareness of sense data, which leads to indirect knowledge of the external world by a process of judgment.
This is by far the greatest threat to Huemer’s project – it challenges his central theses without contradicting the majority of his theory, making it difficult for him to argue against. One defense Huemer could mount is that we are not aware of any process of judgment between perception and awareness. If sense data require judgment to be seen as objects, why do we see objects in the world without having to reflect on them first? The task of filling the breaches in this theory, however, lies with Huemer himself.

Huemer, Michael. Skepticism and the Veil of Perception.Oxford: Rowman and Littlefield Publishers, Inc., 2001.