Hey, Neuroscience, Why Can’t We Be Friends? Objections to Substance Dualism (Part 1)

Posted on October 7, 2015 by

For many who’ve taken philosophy courses at the university level (let alone those who teach philosophy), substance dualism appears to be a theory with, dare I say it, no substance. It’s not a “live option.” But, to extend the pun, I think it’s the dismissal, not the theory, that lacks substance.

In the introduction to this series of posts, I made an analogy between the popularity of students in high school and philosophical theories. Everyone rejects Substance Dualism because, well, isn’t it obvious? He’s a loser. Unlike Physicalism, the coolest kid on the block.Nerd

Well, I predict that at the metaphorical 30 year reunion down the road, all the objections and problems with Physicalism will have caught up to him, and he’ll be looking a lot worse for wear. Meanwhile, Substance Dualism will be looking a lot more attractive, his substantial (but apparently hidden) virtues and qualities having brought him surprising success. And people will realize that their dismissal of this “loser” was based on superficial considerations (read: unwarranted presuppositions).

But I’m an idealist, what can I say…Er, I mean, an optimist—an optimist that people will, in fact, realize how their unwarranted presuppositions were propping up physicalism all along.

Perhaps you think me a naïve optimist. Perhaps you would say in reply, “Physicalism has been overwhelmingly voted ‘most likely to succeed,’ and we just need to give him more time.” Well, have a gander at the first few paragraphs of William Lycan’s paper, “Giving Dualism Its Due,” to read a materialist making more or less the same point that I’ve just made. (Or—because I can’t resist—see this study which claims that “cool kids” in school become “losers” as adults. No offense, Physicalism. It was just a joke.)

What are the objections to substance dualism that give the popular crowd so much confidence in dismissing it at present?

The Objection from Neuroscience

One common objection to substance dualism—though much less common among philosophers of mind—is the objection from the success of neuroscience in discovering tight correlations between the functioning of the mind and the functioning of the physical brain. One gets the impression that new neural correlates for mental processes are being discovered almost daily.

But this objection against substance dualism is based on both misunderstanding and mistaken reasoning.

First, the objection misunderstands what substance dualists claim. Contemporary dualists do not deny the correlations between mind and brain. Even Descartes acknowledged such causal correlations, which is why he sought to explain the causal connection in the first place by suggesting the pineal gland as the locus of causal interaction. Even if neural correlates were discovered for every mental process, dualists would have no trouble acknowledging the correlations. The real question to be answered in the debate is, Are mental processes identical with, or supervenient upon, the physical processes of the brain?

Second, once the real question at stake is understood, this objection can be seen to be based on a simple mistake in reasoning: causal correlation is not the same as identity or supervenience. Even though smoke is correlated with fire, smoke and fire are not identical, nor are they supervenient upon each other. Both are clearly separable from the other; that is, both can exist without the other. The debate between physicalists and dualists is not over whether mental processes are correlated with neural processes. The debate is over whether mental processes are identical with, or metaphysically supervenient upon, neural processes.

No matter how close the correlations are between mind and brain, the question of whether they are identical or whether the mind is metaphysically supervenient on the brain (roughly, the mind cannot change independently of the brain) is a question that must be answered by philosophy, not neuroscience.

What do you think? Have I adequately answered this particular objection adequately? Or does the objection from “psychophysical regularities,” as Robert Koons and George Bealer call it in The Waning of Materialism, still stand?


Note: Please remember the purpose of this series of posts: I am not claiming that, because the major objections fail, substance dualism is correct. I am merely trying to demonstrate that the major objections to substance dualism are not adequate reasons to reject substance dualism.

In other words, regarding this specific objection, even though one might count the correlations we observe between neural processes and mental processes as empirical support for physicalism (they are consistent with what one would expect given physicalism), the correlations do not entail physicalism, and they are empirically consistent with dualism (a robust interactionist dualism that causally links mind and brain in both directions).