Psychology and Indispensability

Abstract

1. IntroductionSome philosophers have alleged that talk of mental states is so vital to our practical and intellectual lives as to be indispensable. Attempting to dispense with such talk has even been said to be 'practically incoherent' or to lead to 'cognitive suicide'. Those philosophers take this to be a serious objection to eliminative materialism. This line of objection raises three questions: What is eliminative materialism? In what sense(s) does eliminative materialism take mental talk to be dispensable? In each sense in which mental talk is indispensable, is its indispensability incompatible with eliminative materialism? The first question will be answered in §2. The second and third questions will be answered in §3. We will see that eliminative materialism can address the above objection by allying itself with fictionalism about mental talk, since fictionalism about Fs is compatible with talk of Fs having a central, even indispensable role in our lives.2. Characterising Eliminative MaterialismOur first task, then, is to say what eliminative materialism is. Here is a proposal. Eliminative materialism has two components:(I) Eliminativism: There are no mental states.(II) Materialism: Internal physical states cause human behaviour.(I) and (II) are ontological claims, not semantic ones (where a semantic claim is one which essentially uses any of the terms 'true', 'false', 'refers', 'entails', or their cognates). (I) and (II) jointly entail various semantic claims, notably:(III) Falsehood: The common sense view of the mental ('folk psychology') is radically false.The idea that a given theory is radically false is the idea that the theory is not false simply in matters of minor detail, but is extensively false in matters of importance-notably in its central principles or laws. Nothing is more central to the common sense view of the mental than that there are mental states. So, if there are no such things, the common sense view is radically false.Some further comments are in order about the relationship between (I) and (II), on the one hand, and (III), on the other. I have taken (I) and (II) to characterise eliminative materialism. I have proposed making the thesis that there are no mental states a core thesis in formulating eliminative materialism. But John Hawthorne (writing as John O'Leary-Hawthome) claims that that thesis is not very interesting (O'Leary-Hawthome 1994, 325). This implies that the above characterisation of eliminative materialism is itself not very interesting. His reason for saying that the thesis that there are no mental states is not very interesting is that there can be nonvacuously true claims about Fs, even if Fs do not exist. After all, he points out, many of us think that, although shadows and holes do not exist, there are sentences about shadows or about holes which are true but not vacuously true. To support that line of thought, Hawthorne appeals to the strategy of paraphrase: if we can paraphrase one sentence in terms of another, and the second sentence can be nonvacuously true even if Fs do not exist, then we have shown that the first sentence can be nonvacuously true even if Fs do not exist.Hawthorne's point raises a question: under what conditions are sentences about Fs (nonvacuously) true although there are no Fs? Here the notion of ontological commitment will help. Let us say that a sentence S is committed to the existence of Fs if and only if the following condition is met: S is nonvacuously true only if there exist Fs. Hawthorne thinks that a sentence which is (apparently) committed to the existence of Fs is nonvacuously true if it can be paraphrased in terms of a sentence which is nonvacuously true and which is not committed to the existence ofFs:We reconcile shadow and hole talk with our ontological eliminativism by showing how talk which appears to treat holes and shadows as objects can be recast as talk which is committed only to the existence of entities that are unobjectionable. …