One of particular importance is the distinction between theories in which the functional characterizations of mental states purport to provide analyses of the meanings of our mental state terms (or otherwise restrict themselves to a priori information), and theories that permit functional characterizations of mental states to appeal to information deriving from scientific experimentation (or speculation).(See Shoemaker 1984c, and Rey 1997, for further discussion and more fine-grained distinctions.) There are other important differences among functionalist theories as well.As an empirical psychological theory, behaviorism holds that the behavior of humans (and other animals) can be explained by appealing solely to behavioral dispositions, that is, to the lawlike tendencies of organisms to behave in certain ways, given certain environmental stimulations.
Thus they seemed to be fit entities to figure centrally in the emerging science of psychology.
Also, behaviorist theories promised to avoid a potential regress that appeared to threaten psychological explanations invoking internal representations, namely, that to specify how such representations produce the behaviors in question, one must appeal to an internal intelligent agent (a “homunculus”) who interprets the representations, and whose skills would themselves have to be explained.
This thesis seems to entail that no creatures with brains unlike ours can share our sensations, beliefs, and desires, no matter how similar their behavior and internal organization may be to our own, and thus functionalism, with its claim that mental states can be multiply realized, has been regarded as providing a more inclusive, less “(species-) chauvinistic” (Block 1980b) — theory of the mind that is compatible with materialism.
(More recently, however, some philosophers have contended that the identity thesis may be more inclusive than functionalists assume; see Section 6 for further discussion.) Within this broad characterization of functionalism, however, a number of distinctions can be made.
Functionalism is the doctrine that what makes something a thought, desire, pain (or any other type of mental state) depends not on its internal constitution, but solely on its function, or the role it plays, in the cognitive system of which it is a part.
More precisely, functionalist theories take the identity of a mental state to be determined by its causal relations to sensory stimulations, other mental states, and behavior.
Though the term ‘functionalism’ is used to designate a variety of positions in a variety of other disciplines, including psychology, sociology, economics, and architecture, this entry focuses exclusively on functionalism as a philosophical thesis about the nature of mental states.
The following sections will trace the intellectual antecedents of contemporary functionalism, sketch the different types of functionalist theories, and discuss the most serious objections to them.
The promise of behaviorism lay in its conviction that there could be a science of human behavior as objective and explanatory as other “higher-level” sciences such as chemistry and biology.
Behaviorism indeed had some early successes, especially in the domain of animal learning, and its principles are still used, at least for heuristic purposes, in various areas of psychology. Chomsky 1959) have argued, the successes of behaviorism seem to depend upon the experimenters' implicit control of certain variables which, when made explicit, involve ineliminable reference to organisms' other mental states.