Functional Role Semantics

According to functional role semantics (FRS), the meaning of a MENTAL REPRESENTATION is its role in the cognitive life of the agent, for example 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. FRS 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 also 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 view originated with Wittgenstein 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; in cognitive science, they include Woods, Miller, and Johnson-Laird.

FRS is motivated in part by the fact that many terms seem definable only in conjunction with one another, and not in terms outside of the circle they form. For example, in learning the theoretical terms of Newtonian mechanics -- force, mass, kinetic energy, momentum, and so on -- we do not learn definitions outside the circle. There are no such definitions. We learn the terms by learning how to use them in our thought processes, especially in solving problems. Indeed, FRS explains the fact that modern scientists cannot understand the phlogiston theory without learning elements of an old language that expresses the old concepts. The functional role of, for example, "principle" as used by phlogiston theorists is very different from the functional role of any term or complex of terms of modern physics, and hence we must acquire some approximation of the eighteenth century functional roles if we want to understand their ideas.

FRS seems to give a plausible account of the meanings of the logical connectives. For example, we could specify the meaning of "and" by noting that certain inferences -- for example, the inferences from sentences p and q to p and q, and the inference from p and q to p -- have a special status (they are "primitively compelling" in Peacocke's 1992 terminology). But it may be said that the logical connectives are a poor model for language and for concepts more generally. One of the most important features of our CONCEPTS is that they refer -- that is, that they pick out objects in the world.

In part for this reason, many theorists prefer a two-factor version of FRS. On this view, meaning consists of an internal, "narrow" aspect of meaning -- which is handled by functional roles that are within the body -- and an external referential/truth-theoretic aspect of meaning. According to the external factor, "Superman flies" and "Clark Kent flies" are semantically the same because Superman = Clark Kent; the internal factor is what distinguishes them. But the internal factor counts "Water is more greenish than bluish" as semantically the same in my mouth as in the mouth of my twin on TWIN EARTH. In this case, it is the external factor that distinguishes them.

Two-factor theories gain some independent plausibility from the need of them to account for indexical thought and assertions, assertions whose truth depends on facts about when and where they were made and by whom. For example, suppose that you and I say "I am ill." One aspect of the meaning of "I" is common to us, another aspect is different. What is the same is that our terms are both used according to the rule that they refer to the speaker; what is different is that the speakers are different. White (1982) generalized this distinction to apply to the internal and external factors for all referring expressions, not just INDEXICALS.

In a two-factor account, the functional roles stop at the skin in sense and effector organs; they are "short-arm" roles. But FRS can also be held in a one-factor version in which the functional roles reach out into the world -- these roles are "long-arm." Harman (1987) has advocated a one-factor account that includes in the long-arm roles much of the machinery that a two-factor theorist includes in the referential factor, but without any commitment to a separable narrow aspect of meaning. Harman's approach and the two-factor theory show that the general approach of FRS is actually compatible with metaphysical accounts of reference such as the causal theory or teleological theories, for they can be taken to be partial specifications of roles.

Actual functional roles involve errors, even dispositions to err. For example, in applying the word dog to candidate dogs, one will make errors, for example in mistaking coyotes for dogs (see Fodor 1987). This problem arises in one form or another for all naturalistic theories of truth and reference, but in the case of FRS it applies to erroneous inferences as well as to erroneous applications of words to things. Among all the conceptual connections of a symbol with other symbols, or (in the case of long-arm roles) with the world, which ones are correct and which ones are errors? One line of reply is to attempt to specify some sort of naturalistic idealization that specifies roles that abstract away from error, in the way that laws of free fall abstract away from friction.

FRS is often viewed as essentially holistic, but the FRS theorist does have the option of regarding some proper subset of the functional roles in which an expression participates as the ones that constitute its meaning. One natural and common view of what distinguishes the meaning-constitutive roles is that they are "analytic." Proponents of FRS are thus viewed as having to choose between accepting holism and accepting that this distinction between the analytic and synthetic is scientifically respectable, a claim that has been challenged by Quine. Indeed, Fodor and Lepore (1992) argue that, lacking an analytic/synthetic distinction, FRS is committed to semantic holism, regarding the meaning of any expression as depending on its inferential relations to every other expression in the language. This, they argue, amounts to the denial of a psychologically viable account of meaning.

Proponents of FRS can reply that the view is not committed to regarding what is meaning constitutive as analytic. In terms of our earlier two-factor account, they can, for example, regard the meaning-constitutive roles as those that are primitively compelling, or perhaps as ones that are explanatorily basic: they are the roles that explain other roles (see Horwich 1994). Another approach to accommodating holism with a psychologically viable account of meaning is to substitute close enough similarity of meaning for strict identity of meaning. That may be all we need for making sense of psychological generalizations, interpersonal comparisons, and the processes of reasoning and changing one's mind.

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-- Ned Block

References

Block, N. (1987). Functional role and truth conditions. Proceedings of the Aristotelian Society LXI: 157-181.

Field, H. (1977). Logic, meaning and conceptual role. Journal of Philosophy 69:379-408.

Fodor, J., and E. LePore. (1992). Holism: A Shoppers' Guide. Oxford: Blackwell.

Harman, G. (1987). (Non-solipsistic) Conceptual Role Semantics. In E. Lepore, Ed., New Directions in Semantics. London: Academic Press.

Horwich, P. (1994). What it is like to be a deflationary theory of meaning. In E. Villanueva, Ed., Philosophical Issues 5: Truth and Rationality. Ridgeview, pp. 133-154.

White, S. (1982). Partial character and the language of thought. Pacific Philosophical Quarterly 63:347-365.

Functional Role Semantics

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