Functionalism

7. Representational content

This further teleological sense of ‘function’ is also relevant to the difficulties functionalists face in accounting for content. Many mental states, and in particular such non-qualitative propositional attitudes as belief and desire, represent states of affairs other than themselves. It is unclear whether the functionalist theory of mental states can account for such representational contents.

One immediate difficulty is that many representational contents are ‘broad’, in the sense that the content of many propositional attitudes seems to depend not just on the thinker’s physical make-up but also on features of the context (see Content: wide and narrow). For example, it is arguable that the possession of beliefs about natural kinds depends not just on the organization of the believer’s brain, but also on features of the believer’s social context and on which natural kinds are present in the believer’s world. This raises a prima facie problem for functionalism. For functionalism makes the possession of mental states depend on the subject’s brain having a certain causal structure. Yet by hypothesis the possession of broad propositional attitudes is not fixed by facts about brains.

However, functionalism has an obvious remedy. There is no obvious reason why functionalism should only consider causal structures inside the head. Why not have a ‘broad’ functionalism, which recognizes ‘broad’ causal structures in which mental states interact, not only with each other and with sensory inputs and motor outputs but also with such external factors as the social environment and objectively existing natural kinds? This would then open the way to a theory which makes the possession of broad propositional attitudes depend on broad causal structures.

So perhaps broad contents present no special problem for functionalism. A more radical criticism of functionalism, however, queries its ability to account for representational contents of any kind, broad or not. Functionalism identifies mental states as items that have certain causes and effects. Yet it is doubtful whether representation can be explained in any simple causal terms.

It might seem that, once we are allowed to appeal to ‘broad’ causal structures, we can identify the contents of beliefs as those external circumstances that typically cause them, and the contents of desires as those external states of affairs to which they typically give rise. But this simple strategy is afflicted by the problem of ‘disjunctivitis’. Take the belief with the content that an ice cream is in front of you. This can be caused, not only by a real ice cream, but also by a plastic ice cream, or a hologram of an ice cream, and so on. Similarly the results which follow any given desire will include not only the real content of the desire, but also various unintended consequences.

So, even if we are allowed broad causal roles that include external causes and effects, we still need somehow to identify, among the various causes that give rise to beliefs, and the various results that eventuate from desires, those which comprise the beliefs’ and desires’ real contents. There are a number of possible ways of doing this. One of the most promising is to appeal to teleological considerations once more. For then we can pick out a desire’s content as that effect which it is the desire’s biological purpose to produce. And, similarly, we can pick out a belief’s content as that condition with which it is the biological purpose of the belief to be co-present (see Semantics, teleological).

One question raised by this appeal to teleology is whether the original functionalism is still doing any work. We started with the functionalist idea that mental states can be identified by their causal roles. But it now seems that, for contentful mental states at least, causal roles are not enough, and need to be supplemented by biological purposes. The obvious question is whether biological purposes would suffice by themselves. Perhaps we can identify contentful mental states by their purposes alone. The answer depends on whether a common biological purpose, but different causal roles, implies different representational states, and relates to a number of currently controversial questions in the philosophy of representation.