Ned Block

This is my first publication of the distinction between phenomenal consciousness and access consciousness, though not using quite those terms. It ends with this: "The upshot is this: If Searle is using the access sense of "consciousness," his argument doesn't get to first base. If, as is more likely, he intends the what-it-is-like sense, his argument depends on assumptions about issues that the cognitivist is bound to regard as deeply unsettled empirical questions." Searle replies: "He refers to what he calls an "access sense of consciousness." On my account there is no such sense."

For nearly thirty years, there has been a consensus (at least in English-speaking countries) that reductionism is a mistake and that there are autonomous special sciences. This consensus has been based on an argument from multiple realizability. But Jaegwon Kim has argued persuasively that the multiple realizability argument is flawed.1 I will sketch the recent history of the debate, arguing that much --but not all--of the anti-reductionist consensus survives Kim's critique. This paper was originally titled "Anti-Reductionism Strikes Back", but in the course of writing the paper, I came to think that the concepts used in the debate would not serve either position very well.

There are two concepts of consciousness that are easy to confuse with one another, access-consciousness and phenomenal consciousness. However, just as the concepts of water and H 2 O are different concepts of the same thing, so the two concepts of consciousness may come to the same thing in the brain. The focus of this paper is on the problems that arise when these two concepts of consciousness are conflated. I will argue that John Searle's reasoning about the function of consciousness goes wrong because he conflates the two senses. And Francis Crick and Christof Koch fall afoul of the ambiguity in arguing that visual area V1 is not part of the neural correlate of consciousness. Crick and Koch's work raises issues that suggest that these two concepts of consciousness may have different neural correlates – despite Crick and Koch's implicit rejection of this idea.

What is Functionalism? Functionalism is one of the major proposals that have been offered as solutions to the mind/body problem. Solutions to the mind/body problem usually try to answer questions such as: What is the ultimate nature of the mental? At the most general level, what makes a mental state mental? Or more specifically, What do thoughts have in common in virtue of which they are thoughts? That is, what makes a thought a thought? What makes a pain a pain? Cartesian Dualism said the ultimate nature of the mental was to be found in a special mental substance. Behaviorism identified mental states with behavioral dispositions; physicalism in its most influential version identifies mental states with brain states. Functionalism says that mental states are constituted by their causal relations to one another and to sensory inputs and behavioral outputs. Functionalism is one of the major theoretical developments of Twentieth Century analytic philosophy, and provides the conceptual underpinnings of much work in cognitive science.

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.