Tuesday, May 24, 2005

Does neurophysiology prove physicalism?

Does the evidence and success of the science of neurophysiology provide overwhelming evidence that the mind is physical? I have some doubts. Now neurophysiology could do two things.

1) It might provide knowledge of correlations between mental states and physical states. It can tell us that while we are dreaming a certain type of neurophysiological activity is going on, and when we are playing chess, another. But a sophisticated dualist like Hasker can say "Of course the ghost needs the machine. Tell me something I didn't know." It seems as if a dualist can easily acknowledge a heavy dependence of the mind upon the brain.

2) Or, it might provide an intertheoretic reduction of mental activity to physical states. This is a much dicier operation, and while I wouldn't want to argue against a neurophysiologist about what mental states are correlated with what brain states (that would be real armchair science, to use Richard Carrier's term) I think that a presumptive case can be made that attempts to analyze the mental in terms of the physical are going to fail; they will end up doing a behind-the-back skyhook, slipping the mental in through the back door and calling it physical, or else it will end up explaining the mental away, explaining it in such a way that it cannot serve as the inferential foundation for the very science of neurophysiology on which the reduction is based. Even though I am not myself a neurophysologist, it seeems that I am competent to raise questions concerning the coherence of intertheoretic reductions.

Do I fail to understand how the neurphysiological argment works?

Also an ionteresting disucssion is going on the Internet Infidels Discussion Board; www.infidels.org. Just click on "forum" and find "philosophy" and the "Richard Carrier's Sense and Goodness Without God." The atheists who have been disucssion with me have been courteous.

13 comments:

Matt Jordan said...

This is a standard substance dualist sort of thing to point out, but I can't help being dismayed by the number of intelligent-seeming folks who can't seem to appreciate the idea that correlation simply doesn't prove identity.

Witness the following quote from a story in today's Canton Repository (note especially the last sentence):

"Sarcasm is used in social situations as an indirect way of expressing
criticism, Shamay-Tsoory said. The network that regulates one's ability
to appreciate sarcasm begins with an understanding of the meaning of
the sentence, which is carried out by the left frontal lobe. Then, the
right frontal lobe helps the person put it into a social context.
Finally, the right frontal lobe must be able to tell the difference
between the literal meaning and what is really meant."

The right frontal lobe "tells the difference"? What does that even mean? What could it mean?

I guess I just needed to get that off my chest.

Blue Devil Knight said...

Neurophysiology hasn't even elucidated a full description of the neuronal correlates of a leech bending, the arm reaching for a cup, or other noncontroversially biological pushings and pullings. Consciousness? Due to the courageous efforts of biologists like Crick, it is only in the past 20 years or so that the word can even be mentioned in neuroscience without a well-founded fear of killing your career.

So, no, neurophysiology certainly hasn't proven physicalism (more precisely, it hasn't proven that the mind is just another biological feature of a beatiful 3 pound organ in our skulls). Finding the "neuronal correlates" of conscious experiences is required before we can have more principled discussions of this issue. The vociferous and shrill arguments from both sides come from people who have made predictions about what we will think about the matter once more science is done. One side predicts that even once neuroscience has revealed all the secrets of the brain, consciousness will still appear a mystery. The other side predicts the opposite. Neither side has good reason to be confident in their predictions based on the evidence right now.

That said, I hope the non-naturalist would not suggest neuroscience stop in its already fruitful exploration of the neural correlates of consciousness, as ably summarized in Koch's book. At the very least, this will lead to useful clinical and theoretical understandings of how brains create minds. Even if dualism is true, this is a necessary step to understand how minds and brains interact, an interaction which even the most flat-footed Christian has to see exists.

I have never read any philosopher that has said neurophysiology has shown that physicalism is true. However, the non naturalist will have a tougher time explaining the systematic correlations between neuronal states and mental states. For the naturalist, this is a smooth and natural (excuse the pun) consequence of her philosophical orientation. Mental states are identical to, or implemented in, physical states, so of course changing mental states will be correlated with changes in physical states.

Blue Devil Knight said...

Note, the idea about the two sides merely being factions making different predictions about what will seem reasonable once we understand the brain is not my own: it is Patricia Churchland's (brilliant) comment.

Matt Jordan said...

I have to disagree with the claim that "neither side has good reason to be confident in their predictions based on the evidence right now." There's no principled reason why the dualist cannot grant for the sake of argument that every mental state has a specific neural correlate or that we can hope to eventually establish a one-to-one correspondence between kinds of mental states and kinds of neural states. (Why, exactly, will the dualist have a difficult time explaining "systematic correlations" between mental and physical states?) That's a much stronger claim than even most naturalists will want to be committed to, of course, but it's entirely compatible with dualism. What's more, it's entirely compatible with the claim that complete knowledge of the brain won't give us any more help in solving the problem of consciousness. This is because consciousness is manifestly different in kind from physical stuff.

Obviously, I'm just re-hashing the old "What Did Mary Know?" sorts of problems. But I'm okay with that. I don't think we have any reason to dismiss that sort of problem, and as long as that's true, the non-naturalist is in a much better position than the naturalist. It seems evident that any genuine explanation of consciousness will not come from mere empirical investigation -- not, at least, without a fundamental shift in the way we conceptualize consciousness itself. So there's awfully good reason to expect that "even once neuroscience has revealed all the secrets of the brain, consciousness will still appear a mystery."

Henry Verheggen said...

Regarding "mental states": Aren't mental states contents of consciousness? For example, I can observe my own thoughts. Therefore mental states are not identical to consciousness.

Matt Jordan said...

I've never really thought about how, precisely, to cash out the difference between 'mental states' and 'consciousness'. Obviously, the terms are not identical in meaning. I guess what I'm inclined to say is that every (occurent) mental state is an instance of the general phenomenon of consciousness. So when one is aware of one's own thoughts, there are (at least) two distinct mental events we can describe. One mental state is the thought itself, the other is the second-order awareness of that thought.

So maybe there's just an equivocation going on. Sometimes we use the word 'conscious' simply to mean "aware," as in the sentence I am conscious of the fact that my son is here with me. But we can also mean "mental" or something like that, as in I am a conscious being. It's this latter use that I had in mind.

Blue Devil Knight said...

Matt Jordan said:

It seems evident that any genuine explanation of consciousness will not come from mere empirical investigation -- not, at least, without a fundamental shift in the way we conceptualize consciousness itself. So there's awfully good reason to expect that "even once neuroscience has revealed all the secrets of the brain, consciousness will still appear a mystery."

This nicely makes my point. You have here made a confident prediction about how you will see things once brain science is complete. It is a prediction because you (and I) are ignorant about what this science will look like, the evidenciary and conceptual resources it will have at its disposal. What seems evident to you is not evident to me, and I make the opposite prediction. However, I can understand why people would be in either faction at this point in time: both sides of this consciousness divide are populated with reasonable people.


At any rate, we need more science. Both sides can sit there and make their predictions about the future. Both sides should want more neuroscience of consciousness to be done, in the very least to help develop safer anaesthetics (agents that remove consciousness) and other clinical applications.

As for dualism having no trouble explaining psychophysical correlations, it seems you blithely underestimate the difficulties of a nonphysical substance interacting with a physical brain. The naturalist faces no such problems. Perhaps a strength of substance dualism is it makes predictions: e.g., violation of conservation of energy that happens when a nonphysical substance causes changes in a physical brain.

Matt Jordan said...

I think I see what you're saying, and I'm at least somewhat warm to it. (And for the record, I'm most emphatically in favor of further neurological research.) Nonetheless, I remain confused. Do you think that brain science will continue to tell us exclusively about physical facts -- i.e. the kind of facts that we're used to getting in the hard sciences? Are the "evidenciary and conceptual resources" you speak of restricted to the domain(s) of physics and chemistry? If so, I stand by my claim. If not, I guess I'm happy to abandon it-- because if science has to admit the existence of non-physical entities to explain consciousness, then I daresay that the dualist has carried the day!

Concerning causal interaction, I grant you that it's a legitimate worry. (Though if you'd like to read it, I will be happy to send you a paper I wrote on the topic for a graduate philosophy seminar.) My point was simply that isomorphic correlations are not a special sort of worry. Causal interaction in general is a problem, sure. But people seem to think that identifying correlations between mental states and physical states (e.g. between c-fibers firing and pain sensations, to borrow the classic example) somehow makes further trouble for the dualist. And that's false.

Blue Devil Knight said...

I assume that neuroscience will remain naturalistic in the sense that brains are composed of cells, ions, synapses, and the like. However, to say that this automatically shows that consciousness is forever outside its scope would be to beg the question.

We know from standard Kripke that semantic analysis is typically not a good guide to metaphysics. Water-H20 style identities could be made in the future: even though your concept of consciousness may not be the concept of a physical or biofunctional process, it could turn out to be that way extensionally just like water turns out to be H20. Philip Kitcher has some great stuff on this in his book The advancement of science, arguing convincingly that even people's 19th century concepts of phlogiston often had an extension (namely, oxygen) even though they had no idea what the correct extension actually was. A beautiful inversion of the usual eliminativist attack!

At any rate, I try not to be dogmatic about the metaphysics of consciousness, except in my insistence that extreme confidence at this point in time is dogma based on a premature prediction.

Matt Jordan said...

It seems to me that an appeal to Kripke here is hardly going to support your claim. I'm not resting my pessimism about science showing us how brains produce minds on a semantic analysis, but on a conceptual one. That's different. Think about 'water' and 'H2O' or about 'phlogiston' and 'oxygen'. Obviously, in either case, the terms in question are not synonyms; they don't mean the same thing. But when we think about the concepts WATER and H2O (or OXYGEN and PHLOGISTON), it's not hard to see (thanks to Professor Kripke) how they could turn out be extensionally equivalent even though the terms we use for them aren't intensionally equivalent.

Now let's turn our attention to mental stuff. I'm not saying that consciousness can't be a product of merely physical processes on the grounds that 'mental' means "non-physical." (Wasn't it Gilbert Ryle who pointed that fallacious move out about 50 years ago?) I'm suggesting the following: Think about what consciousness really is. It's riddled with features--qualia, intentionality, and indexicality, to name a few--that are different in kind from the features of brains and the rest of the (merely) physical world. This is an a priori investigation, of course, and so some will immediately dismiss it out of hand. But anyone who accepts conceptual analysis as a worthwhile endeavor should see what I'm driving at.

Back to Kripke. Consider the following pairs...
'being the stuff that fills lakes' : 'being H2O'
'being the morning star' : 'being the evening star'
'being the stuff that explains why air behaves in certain ways in certain circumstances' : 'being oxygen'
'being a subjective awareness of red' : 'being a neurological event'

If this were the SAT, I would ask you which of the above pairs does not belong to this set. And the answer is the last one. Unlike the others, there is no empirical method we can employ which will allow us to identify the two. (So this would be a pretty tough SAT question, I grant you.) Concerning minds and brains, the most we can hope to establish via empirical enquiry is that mental states are, in fact, correlated with physical states. But as I pointed out in the very first sentence of this discussion, correlation simply doesn't prove identity. So as long as neuroscience only studies the kinds of things studied in physics and chemistry, the mind-brain connection will remain a mystery.

One last thing... By temperment, I share your dislike for unmerited dogmatism. My view is that the above considerations warrant pessimism about science showing us how brains produce minds. What I reject is your earlier claim that "Neither side has good reason to be confident in their predictions based on the evidence right now." The dualist has good reason for such confidence; the physicalist does not. (This oversimplifies the contours of the debate, of course, but you get what I mean.) Nonetheless, the case isn't closed. The kinds of considerations I've raised here might also lead one to believe that light cannot possibly be both a particle and a wave, and we all know how that one turned out. So while I think it's reasonable to maintain my position with confidence, I also think it's mandatory to do so with humility.

Blue Devil Knight said...

Matt, you seem like a thoughtful philosopher, and would be right to think I don't think conceptual or semantic analysis should be used as a guide to metaphysics.

Your post restates your incredulity that subjective states could ever be identified with physical states. I can't accept your claim that focusing on meaning versus reference somehow gets you out of the problem. This has been discussed in the literature extensively. From an article by JC Smart:

Place [1954] remarked:
The logical objections which might be raised to the statement ‘consciousness is a process in the brain’ are no greater than the logical objections which might be raised to the statement ‘lightning is a motion of electric charges’.

It should be noticed that Place was using the word ‘logical’ in the way that it was used at Oxford at the time, not in the way that it is normally used now. One objection was that ‘sensation’ does not mean the same as ‘brain process’. Place's reply was to point out that ‘this table’ does not mean the same as ‘this old packing case’ and ‘lightning’ does not mean the same as ‘motion of electric charges’. We find out whether this is a table in a different way from the way in which we find out that it is an old packing case. We find out whether a thing is lightning by looking and that it is a motion of electric charges by theory and experiment. This does not prevent the table being identical to the old packing case and the perceived lightning being nothing other than an electric discharge.


For the reasons in my response to the indexicals stuff, I think I'll only response to chess topics from now on. :) We won't settle this here: we are in the thick of the Chalmers great divide in consciousness research! I spent three years getting my philosophy Masters worrying about this divide, and left to do neuroscience because I truly believe my above posts.

Best,
Eric

Matt Jordan said...

Well said! And I'm more than happy to end this thread here; I've got term papers to write. Thanks for being so cordial.

Cheers,
mcj

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