Friday, June 3, 2011

Substance Dualism (Part Five): Explanatory Impotence

(Part one, Part two, Part three, Part four)

This is the last in a series of posts on substance dualism. The series has been following the discussion in William Jaworski's book Philosophy of Mind: a Comprehensive Introduction. Having initially addressed the basic argument for substance dualism, we have more recently been concerned with three problems that the substance dualist must confront. Two of these have already been outlined. In this post, the third problem - that of explanatory impotence - will be discussed.

1. Inferences to Best Explanation
If substance dualism is true, then we (persons/minds) can exist without bodies. But if we can exist without bodies, then why is it that we all seem to be attached to a body? If the mind-body relation is not a necessary one, then surely some explanation of this correlation is in order? Aristotle posed this very challenge to the dualist back in the day, and it speaks to an interesting line of criticism - one which crops up again and again in the mind-body debate.

The line of criticism in question - in this case directed at the substance dualist - proposes that if a given theory is a poor explanation of the data that needs to be explained, then it can be dismissed in favour of a better explanation.

This brings us to the concept of inference to best explanation (a concept discussed on this blog before) and the correlative concept of inference from a worse explanation. Both work with abductive arguments and, following Peirce's classic schema, look something like this.

  • (1) H is some data in want of an explanation.
  • (2) E, if true, would account for H.
  • (3) E is a better/worse explanation than all other rival explanations (E1....En).
  • (4) Therefore, E is probably/probably not true.

Formally, this kind of inference commits the fallacy of affirming the consequent. The comparative exercise undertaken in the third premise, combined with the probabilistic nature of the conclusion, is designed to overcome this problem.

2. Is Substance Dualism a Worse Explanation?
The charge here is that substance dualism, when compared to its rivals, is a worse explanation of the available data, and should therefore be dismissed. How is this charge sustained?

First, consider the data that any theory of mind needs to explain. We've already pointed to one element of that data: the apparently steadfast connection and interaction between minds and physical bodies. But the data is more nuanced than that. For one thing, not just any physical body appears to have a mind: only certain evolutionarily recent organisms have that honour. What's more, mental activity is only correlated with certain parts of those organisms: brains and nervous systems, not hairs and fingernails. How do substance dualists account for these particular correlations?

The answer is that they don't appear to be able to do so. In fact, it is in their interests to show that the connection we observe is apparent rather than real. After all, they want to show that there is no essential connection between mind and body.

This highlights a curious feature of the dialectic between substance dualists and their critics. The critics will want to argue that since other theories of mind do account for the puzzling mind-body correlations outlined above, they are stronger and more rationally compelling. The substance dualists will want to argue that a theory which explains mental-physical correlations has no advantages over its rivals. The correlation can either be dismissed as irrelevant or accepted as a brute fact.

Thus, there appears to be real gap between the two sides over what needs to be explained by an acceptable theory of mind. Alas, gaps of this sort frequently emerge in philosophy.

3. Conclusion
In summary, the problem of explanatory impotence may have some force, but this depends on the data we think warrants explanation. I personally feel that the kinds of mind-body correlations discussed by Jaworski merit explanation. Consequently, I would would be disinclined to accept a theory that dismissed them. To shift from this position, I'd need to be convinced that substance dualism had other epistemic advantages. Since that seems unlikely given the other posts in this series, substance dualism is perhaps best left to one side.

All that said, a recent tactic among some proponents of substance dualism is to point out that even if the arguments in its favour are not all that strong, they are no worse than the arguments put forward in defence of, say, physicalist theories of mind. Thus, to cling to substance dualism is no less rational than to cling to physicalism.


  1. Excellent series so far. Will you also review the chapters on Dual-attributive theory and Physicalism?

    There are a couple of typos in the first paragraph from the conclusions :)

  2. Thanks.

    There are four chapters on physicalism. So I'm unlikely to review all of them. I might review the chapters on hylomorphism since that's the theory preferred by Jaworski. I have other things I need to write first though.

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  4. What if the substance dualist used Chalmers' argument from Facing Up to the Problem Of Consciousness--that conscious experience is a fundamental entity--as support for (2)?

    He could then respond to the problem of other minds by noting that other fundamental entities, like matter and electromagnetism, can exist independently without one being grounded in the other; quarks and photons can exist independently, yet there is a consistent causal connection between the two such that observing a certain material state of affairs warrants the belief that an electromagnetic field is present. On that view, it would indeed be surprising if there were not consistent causal relationships between mental entities and physical entities. One should then be warranted in believing that mental entities are present when observing the sorts of physical states of affairs associated with the presence of mental entities.

    This would also give the substance dualist an additional response to the problem of explanatory impotence. If physicalism is unable to explain qualia and the "what it is to be like" of conscious experience, then substance dualism is a superior explanation on that basis. Moreover, one would only expect mental entities to be correlated to physical entities as per the causal relationship between the two. Mental entities ought to be correlated with nervous systems in such a way as to contribute useful features to information processing systems (a means to integrate information, and the addition of qualitative feedback to cognitive processes would be two examples).

    Excellent blog, by the way. I can tell I'm going to be spending many hours going through your archives.

  5. If substance dualism is true then in what matrix does the "mind" exist? In some "supernatural" matrix? So when we are asleep or knocked out, the "mind" is completely elsewhere, in a "supernatural" matrix? Then why don't we wake up with some memory of our minds having been in that supernatural matrix?

  6. Hi Ian,

    Some of that is touched upon in part four. The argument there focuses specifically on the problem of interaction and one suggestion was that the dualist could argue that the causal powers of mental entities are fundamental brute facts, just like the causal powers of physical entities.

    As for there being things that physicalism is unable to account for, yes of course that's going to be a plausible response. I was trying to hint at that at the very end when suggesting they could argue that substance dualism is no worse than physicalism (both account for some data that the other fails to account for). It could also be, as you point out, that substance dualism becomes superior if certain assumptions are granted.


    Interesting question. I'm not too au fait with the literature on substance dualism but I'd be interested if anyone could point me toward articles dealing with that issue. I know that dreaming is sometimes used to support the conceivability argument in favour of substance dualism but beyond that I'm not sure. There are, of course, very interesting discussions of sleep and dreaming from a physicalist perspective (In particular, Guilio Tonoi's and Thomas Metzinger's work).

  7. Edward,

    I've met plenty of people who claim to have memories of the supernatural matrix. Homeless schizophrenics on the street, people who did too much ketamine or salvia, etc. I could ask them why it is that most people don't remember the matrix; I suspect it has something to do with a secret CIA base in Kenosha.


    I've always found substance dualism to be rather weird. This series has helped me to be *slightly* more charitable to the position. If you get the chance sometime, I would love to see coverage of this paper by Mark Balaguer, or a related theory. I'm a compatibilist and a materialist, but this appears to be a way to square libertarian free will with materialism using "torn decisions".

  8. That link doesn't appear to work.

  9. Looks like there might be a decent enough discussion of Balaguer's theory on the (now-defunct) Garden of Forking Paths blog:

    Mark Balaguer - Free Will as an Open Scientific Problem

  10. Thanks very much for that link, John. It does, indeed, cover the paper thoroughly, and Mark even makes an appearance in the comments. Really interesting stuff.