The Problem of Conscious Experience

I OFFER IN this book an account of conscious experience with the aim of serving a particular inquiry. I begin, in Part 1A, with a delineation of this inquiry. In Part 1B, I discuss the bearing of skepticism on the inquiry. Here I introduce Bertrand Russell’s important Acquaintance Model of Experience, which generates an acute skeptical problem for Russell. I critically examine Russell’s response to skepticism.


1. Let us distinguish two types of inquiry. The first type of inquiry is common and familiar. It is pursued in the empirical sciences, and it aims to answer the question, “What facts obtain in the world?” It aims, that is, to provide us with a correct view of the world. This inquiry may lead us—and I will suppose for ease of exposition that it does lead us—to a naturalist view of the world (though it might have led us to a radically different view, e.g., a particular religious view). It is an important element of the naturalist view that we humans do not stand above or separate from nature but are instead fully a part of it. Thus, the first type of inquiry dictates that we improve our understanding of ourselves when we see how our various behaviors and characteristics issue from our natural constitution. Indeed, according to the most prominent version of naturalism—namely, physicalism—the foundation of our behaviors and characteristics lies in our physical constitution.1 This idea applies not only to our bodily and instinctive behaviors, such as breathing and procreation, but also to behaviors that result from deliberation and reflection.
The second type of inquiry—and it is with this inquiry that I shall primarily be concerned—aims to understand what it is that renders a view reasonable. If we accept, say, the naturalist view, we do not do so dogmatically. We do so because we think it is the reasonable view to accept. But what renders a particular view reasonable? The obvious response is: experience and reason. The reasonableness of the naturalist view (assuming it is reasonable) lies in our experiences—naturally occurring experiences, as well as those that occur in the course of our experiments—and in the goodness of reasonings based on those experiences. But what is it for a piece of reasoning to be based on experience? And how does experience bear on the goodness of such reasoning? These are the kinds of questions that the second type of inquiry aims to answer. The inquiry is thus a logical reflection on the inquiry of the first type. The first type of inquiry is conducted under the rubric of reason; it involves argument and debate. The second type of inquiry aims to illuminate the logic of the first type of inquiry.
I will call the second type of inquiry the logical inquiry.2 (I allow myself the definite article because no other logical inquiry will concern me in this book.) I suppose ‘logico-philosophical inquiry’ would be more accurate, but I will stick with the shorter name, for I want to highlight the logical dimension of the inquiry. Indeed, I shall argue that the key to this inquiry lies in pure logic.3 I will call the inquiry of the first type the naturalist inquiry, and here I am naming the inquiry not by something essential to it but by its predominant product.
The account of conscious experience I shall offer is meant to serve the logical inquiry, not the naturalist one. One can, of course, aim to construct a theory of conscious experience within a naturalist setting: just as one can investigate digestion and sleep naturalistically, so one can investigate conscious experience. Indeed, the principal concern in present-day philosophy is with this kind of investigation. The great issue of the day is how to give—and whether one can give—an account that fits conscious experience within a naturalist picture.4 I want to stress that this issue is not my primary concern. Toward the end of the book, I shall reflect on the consequences for naturalism of the account I offer. I shall argue there that the account of experience and reason developed in this book actually helps the naturalist inquiry into consciousness. Until then, however, I wish to bracket the naturalist concern. My sole concern is to find an account of conscious experience that helps make sense of empirical reasoning and of reasonableness of view. It is plain that conscious experience plays some role here. What is this role? And what is it about conscious experience that enables it to play this role? These are the questions that will concern me, not the question of the naturalist standing of conscious experience.
2. Let me highlight some questions and issues that fall within the scope of the logical inquiry and some that do not. The logical inquiry helps us understand, I have indicated, how empirical reasoning depends on experience. Now, two fundamental elements of empirical reasoning are perceptual judgments (e.g., the judgment “this flower is blue” issued in a suitable perceptual situation) and the introduction of new terms and concepts on the basis of experience (e.g., the stipulation “let sepia be the color of that chip,” again issued in a suitable perceptual situation). So, the logical inquiry needs to answer these questions:
(i) What is the bearing of experience on perceptual judgments? How does experience contribute to the content and to the reasonableness of these judgments?
(ii) What is the contribution of experience to the definition of new terms and concepts?
To answer these questions, the logical inquiry needs to address the following, more fundamental, question:
(iii) How is one to think about concepts and judgments and of their relationship to experience?
We shall encounter below several different approaches to these questions and to the logical inquiry, more generally.
3. The logical inquiry reveals, I have noted, what the reasonableness of a view consists in. It renders explicit the commitments we take on when we accept a view as reasonable. It thus illuminates the dialectic underlying our empirical inquiries. The inquiry helps us understand, for example, which sorts of challenges to our view are serious and which are frivolous. Suppose in the course of an empirical investigation, one group of investigators challenges our commonsense conception of color. The group argues that colors are not properties of physical objects, that they “exist only in the mind.” Does the challenge deserve serious consideration? Or should it be dismissed on the ground that the way we learn, say, ‘red’, requires that the word refer to a property of physical objects? Or should the challenge be dismissed on the ground that the investigators are offering merely a new linguistic framework, one that we are within our rights to decline?
Consider another example: Suppose a theorist of human behavior offers the idea that all our vocalizations, including his own, are meaningless. The vocalizations have causal effects but no rational force. Is the theorist’s proposal frivolous, or does it deserve the attention of the students of human behavior?
A final example: Suppose a Cartesian solipsism—the view that nothing exists beyond your mind and its private contents—is put to you as a challenge to your current view of the world. Are you entitled to dismiss the challenge? And if you are, what is the source of the entitlement?
In empirical dialectic, we plainly cannot dismiss all radical challenges to our view. We never would have arrived at our current, rich view had we rejected out of hand all such challenges. Nevertheless, we do not—and should not—treat all such challenges with equal regard. Some radical challenges we celebrate and richly fund; others we dismiss (or confine to the economically deprived philosophy classroom). The differential treatment is reasonable. But what renders it reasonable?
The practice of science is based, at least in part, on our commonsense view of the world. The theoretician, in his struggle to understand perplexing phenomena, plainly has some freedom to reject parts of the commonsense view. But if his rejection is too broad, he risks undermining the very basis of his science. How far can the rejection of the commonsense view go before it becomes absurd? How much theoretical freedom do we enjoy in our empirical inquiries into the world? And what is the nature of the rational constraints that experience and reason impose on these inquiries? These are some of the questions that fall within the scope of the logical inquiry.
4. The logical inquiry, it should be noted, does not aim to explain human behavior. It does not provide psychological explanations of how we form beliefs, nor does it provide a history of how we have arrived at our view of the world. The inquiry is concerned with how we ought to conduct ourselves in empirical debates, not with what our actual conduct has been. The inquiry is thus prospective, not retrospective. Its “theorems” are not of the form “persons in situation XYZ believe such and such propositions,” but closer to the form “it is reasonable for persons in situation XYZ to believe such and such propositions.”5 An understanding of reasonable belief does not automatically provide an understanding of actual belief. Two possible beliefs may be equally reasonable, yet the subject may hold one but not the other, and we may legitimately ask why this is so. This is a psychological question, one that falls outside the scope of the logical inquiry. This inquiry should be sharply separated, therefore, from both psychology and history.
Formal logic and its accounts of deductive validity illustrate the points made in the previous paragraph. An account of deductive validity for a particular domain, say mathematics, does not necessarily provide any explanation of the beliefs of a mathematician. Proofs of equal complexity may be available for two theorems, yet the mathematician may accept one and be oblivious of the other. Formal logic does not provide—and does not aim to provide—any explanation of why this is so. Formal logic provides an account of deductive validity, and this yields a standard by which we can assess proofs. The account can help a mathematician in the construction of proofs. But it is plainly far removed from the psychology of mathematics. As with formal logic, so with the logical inquiry generally. The logical inquiry provides us with tools to assess empirical argumentation, and it can help us engage in such argumentation. But it is far removed from the psychology (and history) of empirical science.
5. The goals of the logical and naturalist inquiries are thus quite different. A naturalist account of human beings does aim to explain behavior, and it may well achieve this aim while bypassing entirely the notion of reasonableness. It is no flaw in a naturalist account—and in fact it may well count as a great virtue—if the account gives a uniform explanation of reasonable and unreasonable assertions; if, that is, it sees both sorts of vocalizations as springing from the same natural constitution (as in vision, e.g., one might explain perceptions and illusions as issuing from the same built-in procedures for processing raw visual data). In itself, it does not even constitute a flaw if the naturalist account does not separate reasonable vocalizations from unreasonable ones, or true vocalizations from false ones.6
The naturalist inquiry aims, then, to explain human behavior, and it may well leave the whole notion of reasonableness in a dark shadow. The logical inquiry, on the other hand, aims to illuminate reasonableness, and it may well leave vocalizations and other human behaviors unexplained.7
6. This difference in goals results in some other noteworthy differences between the two inquiries. First, psychological and intentional notions such as belief and proposition do not enjoy the same status in the two inquiries. In the naturalist inquiry, the usefulness of these notions, and even their legitimacy, is debatable—and has, in fact, been debated. Willard V. O. Quine dismissed these and allied notions as second-class denizens of our conceptual scheme, fit for low-grade work but to be excluded from high science. Wilfrid Sellars accepted a naturalism close to Quine’s, but argued for the opposite conclusion. Sellars thought that psychological and intentional notions meet the strictest demands of naturalist and even behaviorist psychology.8 Whatever one’s allegiances in this debate, it is plain that the issue being debated is real. It is not an absurd thought that a naturalist account of humans will bypass altogether notions such as belief and proposition, that however useful these notions may be in ordinary life, the deepest naturalist account of ourselves will not appeal to them. Neither, of course, is the denial of this thought absurd; hence the legitimacy of the debate.
In the logical inquiry, the status of psychological and intentional notions is entirely different. Here, these notions are not under a cloud of suspicion; they need not establish special credentials before gaining entry into our discourse. The notions are fundamental to the logical inquiry. Indeed, the entire inquiry is framed in terms of them: Why are these beliefs reasonable? Does the possible truth of such and such proposition pose a reasonable challenge to our view? And so on. Of course, it is entirely possible that our conception of some of these notions will be transformed as we pursue the logical inquiry. It is even possible that some of these notions will be found unsuitable and will be eliminated. However, if this happens, it will be for reasons internal to the logical inquiry, not for reasons alien to it.
Let us take a special note of the difference in status of the notion of conscious experience in the two inquiries. In the naturalist inquiry, the notion of conscious experience is a distraction and, frankly, a source of headaches. Even if, afte...