Ned Block

According to Conceptual Role Semantics ("CRS"), the meaning of a representation is the role of that representation in the cognitive life of the agent, e.g. in perception, thought and decision-making. It is an extension of the well known "use" theory of meaning, according to which the meaning of a word is its use in communication and more generally, in social interaction. CRS supplements external use by including the role of a symbol inside a computer or a brain. The uses appealed to are not just actual, but also counterfactual: not only what effects a thought does have, but what effects it would have had if stimuli or other states had differed. The view has arisen separately in philosophy (where it is sometimes called "inferential," or "functional" role semantics) and in cognitive science (where it is sometimes called "procedural semantics"). The source of the view is Wittgenstein (1953) and Sellars, but the source in contemporary philosophy is a series of papers by Harman (see his 1987) and Field (1977). Other proponents in philosophy have included Block, Horwich, Loar, McGinn and Peacocke (1992). In cognitive science, they include Woods (1981) and Miller and Johnson-Laird (1976). (See references in Block, 1987.).

According to The Bell Curve, Black Americans are genetically inferior to Whites. That's not the only point in Richard Herrnstein and Charles Murray's book. They also argue that there is something called "general intelligence" which is measured by IQ tests, socially important, and 60 percent "heritable" within whites. (I'll explain heritability below.) But the claim about genetic inferiority is my target here. It has been subject to wide-ranging criticism since the book was first published last year. Those criticisms, however, have missed its deepest flaws. Indeed, the Herrnstein/Murray argument depends on conceptual confusions that have been tacitly accepted to some degree by many of the book's sharpest critics.

This article compares the three frameworks for theories of consciousness that are taken most seriously by neuroscientists, the view that consciousness is a biological state of the brain, the global workspace perspective and an account in terms of higher order states. The comparison features the “explanatory gap” (Nagel, 1974; Levine, 1983) the fact that we have no idea why the neural basis of an experience is the neural basis of that experience rather than another experience or no experience at all. It is argued that the biological framework handles the explanatory gap better than the global workspace of higher order views. The article does not discuss quantum theories or “panpsychist” accounts according to which consciousness is a feature of the smallest particles of inorganic matter (Chalmers, 1996; Rosenberg, 2004). Nor does it discuss the “representationist” proposals (Tye, 2000; Byrne, 2001a) that are popular among philosophers but not neuroscientists.

The explanatory gap. Consciousness is a mystery. No one has ever given an account, even a highly speculative, hypothetical, and incomplete account of how a physical thing could have phenomenal states. Suppose that consciousness is identical to a property of the brain, say activity in the pyramidal cells of layer 5 of the cortex involving reverberatory circuits from cortical layer 6 to the thalamus and back to layers 4 and 6,as Crick and Koch have suggested for visual consciousness..) Still, that identity itself calls out for explanation! Proponents of an explanatory gap disagree about whether the gap is permanent. Some say that we are like the scientifically naive person who is told that matter = energy, but does not have the concepts required to make sense of the idea. If we can acquire these concepts, the gap is closable. Others say the gap is uncloseable because of our cognitive limitations. Still others say that the gap is a consequence of the fundamental nature of consciousness.

Consciousness is a mongrel concept: there are a number of very different "consciousnesses." Phenomenal consciousness is experience; the phenomenally conscious aspect of a state is what it is like to be in that state. The mark of access-consciousness, by contrast, is availability for use in reasoning and rationally guiding speech and action. These concepts are often partly or totally conflated, with bad results. This target article uses as an example a form of reasoning about a function of "consciousness" based on the phenomenon of blindsight. Some information about stimuli in the blind field is represented in the brains of blindsight patients, as shown by their correct "guesses," but they cannot harness this information in the service of action, and this is said to show that a function of phenomenal consciousness is somehow to enable information represented in the brain to guide action. But stimuli in the blind field are BOTH access-unconscious and phenomenally unconscious. The fallacy is: an obvious function of the machinery of access-consciousness is illicitly transferred to phenomenal consciousness.

Everyone would agree that the American flag is red, white and blue. Everyone should also agree that it looks red, white and blue to people with normal color vision in appropriate circumstances. If a philosophical theory led to the conclusion that the red stripes cannot look red to both men and women, both blacks and whites, both young and old, we would be reluctant (to say the least) to accept that philosophical theory. But there is a widespread philosophical view about the nature of conscious experience that, together with some empirical facts, suggests that color experience cannot be veridical for both men and women, both blacks and whites, both young and old.

Much of recent philosophy of perception is oriented towards accounting for the phenomenal character of perception—what it is like to perceive—in a non-mentalistic way—that is, without appealing to mental objects or mental qualities. In opposition to such views, I claim that the phenomenal character of perception of a red round object cannot be explained by or reduced to direct awareness of the object, its redness and roundness—or representation of such objects and qualities. Qualities of perception that are not captured by what one is directly aware of or by representational content are instances of what Gilbert Harman has called “mental paint” (Block, 1990; Harman, 1990). The claim of this paper is that empirical facts about attention point in the direction of mental paint. The argument starts with the claim (later modified) that when one moves one's attention around a scene while keeping one's eyes fixed, the phenomenology of perception can change in ways that do not reflect which qualities of objects one is directly aware of or the way the world is represented to be. These changes in the phenomenology of perception cannot be accounted for in terms of awareness of or representation of the focus of attention because they manifest themselves in experience as differences in apparent contrast, apparent color saturation, apparent size, apparent speed, apparent time of occurrence and other appearances. There is a way of coping with these phenomena in terms of vague contents, but vague contents cannot save direct realism or representationism because the kind of vagueness required clashes wth the phenomenology itself.

The "great debate" in cognitive science today is about the nature of mental images. One side says images are basically pictures in the head. The other side says they are like the symbol structures in computers. If the picture-in-the-head theorists are right, then computers will never be able to think like people.This book contains the most intelligible and incisive articles in the debate, articles by cognitive psychologists, computer scientists and philosophers. The most exciting imagery phenomena are described, phenomena that indicate that mental images can be rotated and scanned, that smaller images are harder to see than larger ones, that when mental images are made larger they eventually overflow, that the "screen" they overflow from has a determinable shape (elliptical), and that this "screen" subtends a determinate visual angle, the angle of vision of the mind's eye.Such experiments cry out for explanation. If images are pictures in the head, who (or what) looks at them? Why haven't brain scientists found them? Such questions are the subject of the great debate.IMAGERY is an excellent choice for courses in cognitive psychology, perception: artificial intelligence, computer science; philosophy of mind, of psychology and of science; minds and machines, science and society.Contributors include: Roger Brown and Richard Herrnstein (on the work of Roger N. Shepard), Daniel Dennett, Jerry Fodor, Robert Schwartz, Stephen Kosslyn, Steven Pinker, George Smith, Steven Shwartz, and Zenon Pylyshyn