Abstract
In this paper I examine Chalmers and Jackson’s defence of the a priori entailment thesis, that is, the claim that microphysical truths a priori entail ordinary non-phenomenal truths such as ‘water covers 60% of the Earth surface’, which they use as a premise for an argument against the possibility of a reductive explanation of consciousness. Their argument relies on a certain view about the possession conditions of macroscopic concepts such as WATER, known as ascriptivism. In the paper I distinguish two versions of ascriptivism: reductive versus non-reductive ascriptivism. According to reductive ascriptivism, competent users of a concept have the ability to infer truths involving such concept from lower-level truths, whereas according to non-reductive ascriptivism, all that is required in order to be a competent user of a concept is to be able to infer truths involving that concept from other truths, which need not be lower-level truths. I argue, first, that the a priori entailment thesis is committed to reductive ascriptivism, and secondly, that reductive ascriptivism is problematic because it trivializes the notion of a priori knowledge. Therefore, I conclude that Chalmers and Jackson have not presented a convincing case for the claim that microphysical truths entail ordinary non-phenomenal truths a priori, especially when we understand this claim in the sense that is relevant for their argument against the possibility of a reductive explanation of consciousness.
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Notes
Here I follow the exposition of the argument by Chalmers and Jackson (2001, p. 315).
See, for instance, the papers collected in Shear (1997).
This is a response to Block and Stalnaker (1999), who deny the possibility of providing definitions for macroscopic terms in microphysical terms.
There are many defences of non-ascriptivism in the literature, such as Levine (2001), Block and Stalnaker (1999), and others. For instance, Block and Stalnaker say: “there is no way to fill in the details of ‘the water role’ so that it is a conceptual truth that water occupies the water role” (1999, p. 16). In the same line, Levine argues that the sentence ‘water is watery’ (where ‘watery’ is a description of the water-role) is not a priori (2001, pp. 55–66).
Levine (2001) also suggests that it is not necessary to reject ascriptivism in order to attack the a priori entailment thesis.
Notice that if phenomenal truths were a priori entailed by microphysical truths, that is, if P entailed Q a priori, then we would not need to add Q to P. But, since we cannot assume this at this point, we have to explicitly add Q to P, in case P does not entail Q a priori. See Chalmers and Jackson (2001, pp. 318–320) for further discussion.
Notice that when we add Q to P, the “that’s all” clause changes its meaning slightly: the claim is no longer that there is nothing over and above what P says, but rather that there is nothing over and above what P and Q say.
Actually, given how I have formulated both theses, there is also space for some additional, hybrid views. However, they are not relevant for the line of argument here, so we can put them aside for the sake of simplicity. Nothing hangs on this simplification.
The principle (Word-Concept), which I introduce below, points in this direction.
See Chalmers and Jackson (2001, p. 328).
It could be argued that what is relevant here is whether the information encapsulated in the primary intension of a term such as ‘condensation’ is known a priori or not. Therefore, perhaps the empirical facts about condensation that we are referring to are not relevant here: what is relevant is the causal-functional role that we associate with ‘condensation’, and not the microscopic properties that happen to realize that role in the actual world. The main idea here is that the information that is relevant in order to know the application conditional for CONDENSATION (and therefore being an expert concerning such a concept) is information about the causal-functional role of condensation, not about the microscopic properties responsible for condensation at a chemical level. My reply to this objection is twofold. On the one hand, I think that Chalmers & Jackson’s thesis of a priori entailment requires that we are able to apply some macrophysical concepts to a microphysical description, and in order to do that it is not enough that we know the causal-functional roles associated with those macrophysical concepts: we also have to be able to apply these roles to a microphysical description, and it seems that we need to be able to apply some macrophysical concepts to a microphysical description, in order to do that. On the other hand, we are assuming here that for many physical concepts (those invoked in P) the primary and the secondary intensions coincide, and therefore knowing the primary intension would require knowing the secondary intension. In any case, it seems clear that Chalmers and Jackson are committed to the view that in order to be experts concerning many macrophysical concepts, we have to be able to apply them to a microphysical description, and this seems to require the kind of application conditionals that we are discussing here.
References
Block, N., & Stalnaker, R. (1999). Conceptual analysis, dualism and the explanatory gap. The Philosophical Review, 108(1), 1–46.
Chalmers, D. (1996). The conscious mind. New York: Oxford University Press.
Chalmers, D., & Jackson, F. (2001). Conceptual analysis and reductive explanation. The Philosophical Review, 110(3), 315–361.
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Acknowledgements
I am grateful to the Arts and Humanities Research Council, the University of Sheffield, and the Royal Institute of Philosophy for financial support during the writing of this article. Ancestors of this paper have been presented at the following conferences: V Taller d’Investigació en Filosofia at the University of Barcelona in January 2003, IV Congress of the Spanish Society for Analytic Philosophy at the University of Murcia in December 2004, VII Taller d’Investigació en Filosofia at the University of Valencia in January 2005, and the XIII Annual Meeting of the Association for the Scientific Study of Consciousness in Berlin, June 2009. I am very grateful to audiences in all those occasions for very useful feedback. Special thanks are due to the following people for very helpful comments to earlier versions of this material, illuminating discussions, and encouragement: Saray Ayala, Ned Block, Jose A. Díez, Manuel García-Carpintero, Rosanna Keefe, Uriah Kriegel, Stephen Laurence, David Liggins, Dan López de Sa, Luis Robledo, Sonia Roca, and Jennifer Saul. Finally I wish to thank an anonymous referee for this journal for very useful suggestions.
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Diaz-Leon, E. Reductive explanation, concepts, and a priori entailment. Philos Stud 155, 99–116 (2011). https://doi.org/10.1007/s11098-010-9560-x
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DOI: https://doi.org/10.1007/s11098-010-9560-x