Mind, philosophy of

2. Mind and meaning

As these last issues indicate, any theory of the mind must face the hard topic of meaning (see Semantics). In the philosophies of mind and psychology, the issue is not primarily the meanings of expressions in natural language, but of how a state of the mind or brain can have meaning or content: what is it to believe, for example, that snow is white or hope that you will win. These latter states are examples of Propositional attitudes: attitudes towards propositions such as that snow is white, or that you will win, that form the ‘content’ of the state of belief or hope. They raise the general issue of Intentionality, or how a mental state can be about things (for example, snow) and properties (for example, white), and, particularly, ‘about’ things that do not exist or will not happen, as when someone believes in Santa Claus or hopes in vain for victory.

There have been three main proposals about mental content. A state might possess a specific content: (i) by virtue of the role it plays in reasoning (see Semantics: conceptual role); (ii) by virtue of certain causal and lawful relations the state bears to phenomena in the world (see Semantics: informational; Functionalism); or (iii) by virtue of the function it plays in the evolution and biology of the organism (see Semantics: teleological; Functional explanation). Related to these proposals are traditional philosophical interests in Concepts, although this latter topic raises complicating metaphysical concerns with Universals, and epistemological concerns with A priori knowledge.

Special problems are raised by indexical content, or the content of thoughts involving concepts expressed by, for example, ‘I myself’, ‘here’, ‘now’, ‘this’, and ‘that’ (see Content, indexical; Demonstratives and indexicals; Propositional attitudes §3). Does the thought that it is hot here, had in Maryland, have the same content as the thought that it is hot here, had in Canberra? The conditions under which such thoughts are true obviously depends upon the external context – for example, the time and place – of the thinking.

This dependence on external context is thought by many to be a pervasive feature of content. Drawing on recent work on reference (see Reference; Proper names), Hilary Putnam and Tyler Burge have argued that what people think, believe and so on depends not only on how they are, but also upon features of their physical and social environment. This raises the important question of whether an organism’s psychology can be understood in isolation from the external world it inhabits. Defenders of methodological individualism insist that it can be (see Methodological individualism); Putnam, Burge and their supporters that it can’t. Some theorists respond to the debate by distinguishing between wide and narrow content: narrow content is what ‘from the skin in’ identical individuals would share across different environments, whereas wide content might vary from one environment to the next (see Content: wide and narrow). These theorists then give distinctive roles to the two notions in theoretical psychology, although this is a matter of great controversy.