Functionalism

2. Common-sense and scientific functionalism

There are various brands of functionalism. One division depends on whether the theory T used to introduce mental terminology derives from common-sense psychology or from scientific research. This issue also determines whether functionalism can claim to give an account of the meaning of everyday mental terms like ‘desire’ and ‘pain’.

If the theory T is derived from common-sense psychology, then it is open to functionalists to argue that the resulting Ramsey-style account of mental discourse explicates what everyday people mean by terms like ‘desire’ and ‘pain’. That is, they can argue that these terms, in everyday discourse, simply signify ‘the causal roles specified by T’.

On the other hand, if the theory T used to introduce mental terminology is not part of everyday thinking, but rather some new scientific theory, then it cannot plausibly be argued that everyday thinkers derive their grasp of terms like ‘desire’ and ‘pain’ from this theory. So functionalists who want to replace common-sense psychology by some new scientific theory need to view the Ramsey-style account as fixing the meaning of new technical terms, which signify the causal roles specified by the new scientific theory. It is then open to them to argue that the states picked out by their technical terms are in fact the same states as referred to by the everyday terms ‘desire’ and ‘pain’. But, from the point of view of this kind of scientific functionalism, this will be a synthetic matter, to be supported by empirical evidence, and not a matter of definition.

The former kind of functionalism, which I am calling common-sense functionalism, is sometimes also called ‘analytic’ functionalism, in recognition of the fact that it makes it a matter of definition that everyday mental terms stand for certain theoretical roles. It is perhaps worth pointing out, however, that the common-sense theory T involved in these definitions will not itself be analytic. What is analytic is this claim: if there are states which play the roles specified by T, then these states are desires, pains, and so on. But the further claim, that there are in fact such states linking sensory inputs with behavioural outputs, is obviously synthetic.

One issue facing both common-sense functionalists and scientific functionalists is how much of the relevant theory to count as contributing to the meanings of mental terminology. It is obviously unsatisfactory to include all the many assumptions of everyday or scientific psychology in our Ramsey-style definitions of mental terms. For it would then follow that, if any single one of these assumptions turns out to be false, then all these terms will fail to refer to anything (since there will not then be any states which play the precise causal roles specified by the original incorrect theory).

The obvious remedy is to argue that only some core set of assumptions from the relevant theory plays a part in fixing the meanings of its terms. This would in effect make it an analytic requirement that desires, or pains, or whatever other mental states are at issue, satisfy the relevant core assumptions, while leaving it synthetic that they satisfy any further assumptions. However, there are general doubts about any sharp analytic-synthetic distinction of this kind. What principled reason could there be for picking out certain theoretical assumptions as constitutive of the meaning of ‘desire’, say, while excluding others? Perhaps the best solution for the functionalist would be to postulate some more-or-less vague distinction between the central and non-central assumptions of the relevant theory, and then take it to be a matter of meaning that the various mental terms will satisfy most of these assumptions. This will admittedly make it a vague matter whether the relevant mental terms apply to states which do not satisfy all the central assumptions; but this vagueness is arguably a feature of all theoretical terminology in science, and not necessarily vicious.