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How to be a type-C physicalist


This paper advances a version of physicalism which reconciles the “a priori entailment thesis” (APET) with the analytic independence of our phenomenal and physical vocabularies. The APET is the claim that, if physicalism is true, the complete truths of physics imply every other truth a priori. If so, “cosmic hermeneutics” is possible: a demon having only complete knowledge of physics could deduce every truth about the world. Analytic independence is a popular physicalist explanation for the apparent “epistemic gaps” between phenomenal and physical truths. The two are generally seen as incompatible, since the demon’s deductions seem to presuppose analytic connections between physical and phenomenal terms. I begin by arguing, in support of the APET, that implications from the complete truths of physics to phenomenal truths cannot be a posteriori. Such implications are (according to the physicalist) necessarily true. But they cannot be Kripke-style a posteriori necessities, since (according to the physicalist) the complete truths of physics fix any relevant a posteriori facts about the reference of terms. I then show how the physicalist can turn the tables: the demon can exploit the physical fixing of reference to bridge the gap between the vocabularies, by deducing when phenomenal and physical terms co-refer. This opens the way for a “type-C” physicalism, which accepts in-principle deducibility while still appealing to analytic independence to explain why we (who are not demons) find it impossible to see phenomenal-physical connections a priori.

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  1. I use “truth” for true statement; “fact” for a (genuine) feature of the world. Truths state facts. Note that the demon knows the truths of physics past, present and future. There is a distinct question (which Horgan calls “cosmic number-crunching”) as to whether a Laplacian demon which knew only about the present could deduce the past and future.

  2. Levine (1983, 2001) argues that there is also an “explanatory” gap: physical truths can never adequately explain phenomenal truths. This gap is, he argues, distinct from the question of a priori entailment. If so, it lies beyond the scope of this paper.

  3. This approach is often called the “phenomenal concept strategy”, a label which is apparently due to Stoljar (2005)

  4. Notably Chalmers and Jackson (2001), Jackson (1998) and Lewis (1999), as well as Horgan.

  5. The label “type C” comes from Chalmers’ (2003) classification of views on the mind–body problem. Views such as Loar’s, on which the relation between phenomenal and physical truths is entirely a posteriori, are type B. Views such as Lewis’s (1999), on which phenomenal truths follow analytically from physical truths, are type A. Type-C physicalism, in general terms, is the view that while phenomenal truths are deducible from physical truths, something prevents us making the deductions—which might be ignorance of the antecedent (as I argue) or cognitive closure (McGinn 1989).

  6. The term “minimal physical duplicate” comes from Jackson (1993). Physicalism allows that physical duplicates of our world which are not minimal physical duplicates may differ from our world, e.g., by containing ectoplasm.

  7. See Dennett (1990) for a denial that anything has these features.

  8. For simplicity, assume that all terms used in P and R are rigid designators, so that there is no question of P ⊃ R being false of a world w simply because some term picks out different things in w and the actual world. Any non-rigid designators can be “rigidified” by stipulation (Kripke 1981, p. 149). In fact, this assumption can be dispensed with, for a reason that will emerge in the next section.

  9. Further complications are sometimes introduced to deal with Perry’s claim that indexicals cannot be deduced from non-indexicals (Perry 1979), but I will pass over those here.

  10. Horgan’s defence in (1983) does not specifically address phenomenal consciousness.

  11. Versions of this “semantic stability” point are pressed by, for example, Chalmers (2010), White (2007), and Kripke himself (1981, lecture III). I am sceptical that any terms are stable in this sense, but I will not address the question here.

  12. That assumption is contested, of course. I make it here because the question is whether physicalism is committed to a priori entailment, and physicalism includes physicalism about reference. In Sect. 7 below I discuss what happens if this assumption is false.

  13. This is why, as mentioned in footnote 8, it doesn’t matter if terms in P and R are non-rigid. If, as the physicalist claims, the reference of terms in R is determined by facts stated by P, their reference cannot vary in P-worlds—except as a result of corresponding variation in the reference of terms in P. Accordingly, P ⊃ R will retain its truth value across worlds.

  14. My notation, not Dowell’s.

  15. See Sect. 4.1.

  16. Not given the APET, the physicalist doesn’t need to claim that P ⊃ S is a priori, since type-B physicalism is back on the table.

  17. At this point the demon’s inference resembles that suggested by Dowell (2008, p. 105), but on Dowell’s view, the analogue of (1) is not deducible from P (see Sect. 4.3). For Dowell, a priori implications from truths like (1) replace implications from fundamental physical truths alone in reductive explanations; while on the view I am arguing for, truths about reference serve as an avenue along which a priori implications from fundamental truths can run.

  18. Thanks to an anonymous reviewer for raising this point.

  19. Premise (1) is a posteriori despite being implied a priori by P, since P is itself a posteriori.

  20. As mentioned in Sect. 2.1, I count physically realised functional phenomena as physical phenomena.

  21. Again, I set aside the question of “semantic stability” (footnote 11 above). Type-C physicalism stands or falls with type-B on that issue.

  22. That latter describes, e.g., Stoljar’s view (2006, p. 122). Thanks to Tom McClelland for the Rumsfeldism.

  23. Crane (2003) argues that Mary could not have known that “phenomenal redness is like this”, since her lack of red experiences means that any use by her of the demonstrative “this” must have referred to something else. Still, as Crane says, there is no problem for physicalism here.

  24. At least, in her original incarnation (Jackson 1982). In (Jackson 1986) she is given knowledge of all the physical facts.

  25. See the “experienced Mary” case discussed by Stoljar (2005).

  26. For a recent argument, see Wedgwood (2009).

  27. Positions of this kind are taken by Lycan (1987, p. 80), Hill (2009), and Crane (2009).


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I would like to thank Tim Crane, Matt Nudds, Tom McClelland and an anonymous reviewer for helpful comments and discussions. Special thanks are due Alex Oliver for comments and support throughout the paper's development.

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Correspondence to Adrian Boutel.

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Boutel, A. How to be a type-C physicalist. Philos Stud 164, 301–320 (2013).

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  • Phenomenal consciousness
  • Type-C
  • Physicalism
  • A priori entailment thesis
  • Analytic independence
  • Cosmic hermeneutics