Thursday, July 03, 2008

Brain Damage and Physicalism

Ookla-fry writes:
If dualism were correct then brain damage wouldn't effect cognitive ability. Simple as that.

This is a surprisingly common misconception. (Neuroscience student K.L. Dickson makes similar claims here.) It arises from a simple confusion of necessary and sufficient conditions. Dualists claim that the physical brain does not metaphysically suffice for mentality (cf. zombies). But Ookla's claim simply doesn't follow from this -- we may still think that the brain plays an essential, but non-exhaustive, role in constituting our minds.

A typical physicalist view is that the mind just is the brain. A dualist view is that the mind arises from the brain (given appropriate background conditions). Nobody holds that the mind is nothing at all to do with the brain.


  1. It's an important point. Even substance dualists, who go farther than the sort of dualism you're looking at here, don't hold that the mind has nothing to do with the brain. The Cartesians themselves put a great deal of emphasis on the brain, and explained a great deal of cognitive functioning in terms of the 'Cartesian philosophy of the brain' (to use Hume's phrase for it). So you can have a very strong dualism that still insists that states of the brain affect cognitive ability.

  2. Well some people do... pre-established harmony seems to make the mind have 'nothing to do' with the brain in the sense you intend, i.e. there is no metaphysical dependence of the one on the other.

    1. Agree. Many commonly held views of dualism do lead to the conclusion that the mind is independent of the brain. Also, if the brain plays an essential role, you still have the quandary of how do they interact.

  3. "Nobody holds that the mind is nothing at all to do with the brain."

    I agree with Colin. The above statement is very strong. Some physicalists will point out that the "Why The Meat?" objection is an extension (no pun intended) of the interaction problem, among others.

    "A typical physicalist view is that the mind just is the brain. A dualist view is that the mind arises from the brain (given appropriate background conditions)."

    The former sentence is not exhaustive of all physicalisms, whereas the latter may represent a property dualism or a simple form of emergentism, both, if formulated correctly, entirely compatible with physicalism.

  4. (hi)

    Personally I'm inclined to accept the mind is entirely caused by the brain but they are not the same thing.

    I have found it impossible to make a selection of psychologists even understand this (as far as I could tell) face to face. So good luck with your neuroscientist.

  5. Consciousness consumes oxygen, if we deprive you of oxygen we deprive you of consciousness and ultimately life if held long enough, that's enough evidence for me to know that the mind is at least bound to the universe in it's essential operation.

    I think the better question is, considering quantum mechanics, is physicalism a cohernet concept if the universe is actually made of waves?

  6. Dualists do not a priori believe that consciousness has a physical component.

    Imagine living 500 years ago. Peter says the mind is a physical mechanism, Dave says it's not all physical. Now what are Peter's predictions? Peter's predictions are that every cognitive function can be intercepted or corrupted by physical means. Meanwhile, Dave's predictions are that every cognitive functions may or may not be corrupted by physical means.

    Centuries pass, and we find that, at every opportunity, Peter's predictions are validated. Dave's theory has not been absolutely ruled out, but it has been ruled out statistically. What are the odds that Dave's dualism is that one rare form of dualism that looks exactly like Peter's physicalism?

    Today, one would be guilty of gross fine-tuning (and gap argumentation) to suppose that Dave's theory were likely to be true.

    The question is, does the zombie argument impose million(or billion)-to-one statistical argument that can cancel out all of Peter's data for the last 5 centuries?

    No. The premise of the zombie argument is that human zombies are possible, i.e., that physicalism is insufficient to explain qualia. But qualia may not exist as non-causal elements. The uncertainty in this is on the order of 50%. If we were billion-to-one certain that qualia existed as an non-causal part of the story, then Dave could happily sustain his debate with Peter. But that's just not the case.

  7. Re: "... the physical brain does not metaphysically suffice for mentality."

    I have no idea what 'metaphysically suffice' means.

    It is a empirically testable consequence of the physicalist hypothesis that brain damage should significantly alter cognitive function. However, the dualist can make no such testable deductions. Rather, the dualist simply 'metaphysically' posits that non-physical stuff (whatever that amounts to) 'just does' constitute so-called mental events.

    In fact, with Doctor Logic, I see no reason whatsoever why a brain or some other physical object should be necessary for cognitive function under the dualist hypothesis.

  8. I guess the argument that Chalmers et el make is that, in the case of other phenomenon, it's always been clear that the problem has been figuring out function. Why think the naturalistic induction work with phenomenon that aren't obviously functional?

    You could argue against this view by suggesting that other phenomenon were thought to play nonfunctional roles and then were discovered to have functions--but I don't think that's the case. Each case of supernatural gone natural explanation, the people said the function would be too weird or too hard. But the question was still functional.

    Perhaps some conceptual revolution will take place and we'll see how qualia will be thought of as playing some function. However, there isn't precedent for anything like this so I'd give (epiphenomal) dualism anywhere from a 50-75% of being correct.


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