Against Chalmers on Identity and Supervenience


This post airs my thoughts concerning the relation of supervenience and the history of science, with bad results for certain criticisms of naturalist metaphysics. It will make sense to you if follow topics like supervenience, metaphysical zombies, twin earths and qualia.  It is also very relevant to debates concerning moral naturalism, the naturalistic fallacy, and G.E. Moore’s ‘Open Question’ argument.  I will make this connection in a future post, although my “God vs. the Fact/Value Distinction” already deals with this in preliminary way. This line of thought is necessary to defend “The Theory of Ethical Selection”, against the most powerful criticisms of moral naturalism.

Supervenience and reductionism.

Chalmers, myself,  and most other scientifically-minded people would admit that if you have a certain physical arrangement of atoms in possible world ‘W’, then all of that world’s positive biological facts follow necessarily from that arrangement. While life is not in some ways reducible to an arrangement of matter, but you can’t differ biologically without differing physically. This may not be identical with many ideas concerning materialist ‘reductionism’, but that’s what most biological naturalists believe, and I don’t really need anything stronger to justify my version of naturalism. Philosophers such as Chalmers sum this idea up thusly: “biological facts are ‘logically supervenient’ on physical facts”. This means that all possible worlds that are physically identical will also be biologically identical. Chalmers agrees with this and in my view is therefore a biological naturalist. However, he writes an entire book attacking the thesis of naturalism with respect to one aspect of mind: phenomenal consciousness (a.k.a. ‘qualia’). On his view consciousness is not logically supervenient on biology in the same way that biology is on physics. On this view, metaphysical zombies are possible, since there is no clear sense in which qualia are necessarily physical.

The opposing thesis of “qualia naturalism” holds that any world W where all physical and biological facts are the same, all ‘qualia-facts’ will also be the same. In other words, metaphysical zombies are impossible. Chalmers defends qualia non-naturalism, meaning that biological facts do not determine the qualia-facts and two worlds could be physically identical while differing in having qualia.

Most people would have their doubts as to whether consciousness is logically supervenient on biological and physical facts.  I’m a naturalist in both biology and mind, but I’m far more certain of the former than the latter. Why is this that case? What is the basis for these intuitions? In my view,it hinges on debates concerning the metaphysics of identity relations and how scientific theory relates to supervenience (both logical and natural).

Examples from the History of Science

To illustrate my reasoning on this, begin with a simpler case: it’s quite unremarkable to claim that lightning is supervenient on physical facts. Everyone knows that in modern terms “lightning is just a form of static electricity”. Most people today would agree with me, but long ago people tended to disagree, and with some good reason.  Long ago, reductionistic theories of lightning were not even advanced to the level of testable hypothesis. Epicurus says nothing of static electricity,even though he was clearly a lightning naturalist. I think the ancients were aware of static cling resulting from rubbing pieces of amber, but no one had any clue that it might have anything at all to do with lightning. In fact, lightning was almost universally considered to be a supernatural phenomenon and the majority of the human race is inclined to agree even today. Bach then few ‘lightning naturalists’ had no real proof, only mere speculation about atomic “seeds of fire”  awaiting some catalyst to release them.

Similarly, prior to the invention of the microscope, reductionistic or atomistic theories of biology were also relatively unwarranted. If Chalmers and other biological naturalists had published their views back then, even scientists would laugh at his wild speculation that “biological facts are supervenient on physical  [meaning “atomic”] facts”. At this time some smart people were speculating that this was the case, but it was still merely speculation and the dominant ‘theory’ of life was vitalistic. And I think it is safe to say that vitalism is the thesis of biological non-naturalism. On this view, you ca arrange matter however you like, but you will still be lacking life.

Even today, you can find many reasonable people who would doubt biological supervenience because it contradicts ‘common sense’. What makes Chalmers so sure that they’re wrong? Perhaps because we are privy to the results of evolutionary biology. This theory is so conclusive as to silence all doubt on the issue. A hundered years ago, we knew about evolution but even then biological naturalism in this philosophical sense was not yet proven.  On my view (and on this depends my whole argument), the current state of the relevant fields of science is the only basis of judgments of logical supervenience.
The only reason Chalmers accepts biological naturalism is because he accepts a certain empirical theory that supports supervenience between the physical and the biological. It’s not like vitalism has been disproven; it’s not really meaningful enough to function as a theory at all. So also are all forms of non-naturalism; you can never prove them wrong because they say nothing about anything at all. Naturalism says a lot; among other things is says that qualia are supervenient on the biological and thus also the physical. This means that for each different qualia, there will be a corresponding physical arrangement. I’m sure that many a non-naturalist will claim that this is also meaningless. I will not bother to argue against that, I will merely point out that this is far more meaningful that non-naturalism which makes no claims of any sort about the relations of qualia to anything at all. In this sense, it’s just like vitalism. Both claim that there is this magical juju which for some reason seems to have some correlation with living things, but in reality, there is no reason given for this in the theory, whereas for naturalism, the reason is very clear: the genus “living creatures” represent a distinct physical arrangement, and animals (which have qualia) are a species within this the genus.

When a similar theory is proposed and accepted in cognitive science, then perhaps even Chalmers should accept naturalism with respect to qualia. Another way of saying this is that even logical supervenience expresses an a posteriori identity. All of the relations of logical supervenience (such as between biology and physics) accepted by Chalmers  in his work are a posteriori in this same way. The result is that if our current understanding of the physical base expands in some fundamental way then at that point consciousness may become logically supervenient on that new base, and naturalism becomes true. The historical examples of lightning and vitalism were given to illustrate that whether or not logical supervenience holds is a posteriori. The identity relation between the two things is dependent on how well understood the field is, and this level of understanding is one of development of empirical science, not armchair philosophical hairsplitting a la Chalmers.

The Upshot

My point is three fold:

1) Any theory which will possibly explain anything at all assumes that logical supervenience holds between two levels.

2) However, logical supervenience establishes a priori identity only through the historical process of scientific advance which changes the meanings of concepts through empirical research.

3) Until the theory is thoroughly proven, it will be TOO reductive to everyone except its initial creators and defenders. Whichever theory is true, it must make some hypothesis that logical supervenience holds between two levels. We don’t know which theory is correct yet (if any), but whichever it is, it must satisfy this condition.

3) If it is thoroughly proven, then it remains just as ‘reductive’ as it ever was, but is never said to be so, it i merely said to “explain” things.

Of course I might be wrong, especially if there is some other sort of ultimate explanation than reductive analysis. I agree that there are other sorts of explanations for things besides reductive; for example, I can explain behavior teleologically or formally. Why does a person eat lots of cheeseburgers? Perhaps they like cheeseburgers. This is a nonreductive explanation using Aristotle’s “final cause”, but I would claim that there are more fundamental levels of explanation above this one, and the highest levels will have to resort to Aristotle’s material and efficient causes. This is not a necessary conceptual truth, and would not have been able to convince Aristotle in his day without access to modern science. However, if we were to bring him forward in time, we could justify it to him by appeal to his definition of the “arche” (or higher/-est principle) as we understand it today.

In Aristotelian terms ( given molecular biology, Mendelian genetics, and Darwinian evolution ) we are now able to show that “liking cheeseburgers” falls into the category of a possible arrangement of matter and energy.  This is in fact what it means to “explain” something. It still makes sense for a normal person to explain something with reference to final causes. It also works in fields where we take people’s preferences and initial data such as economics. But for an explanation from “FIRST principles”, we must explain it in terms of the most universal principles known.  This means that some entities must be reduced to other entities.

My explanation for phenomenal consciousness has a strong teleological component: I claim that phenomenal consciousness serves an  adaptive function.  Chalmers cannot imagine that it has a functional character, but that’s his problem, not mine. I can’t imagine how someone could go through the trouble to write such an nice book explaining the problem in such detail without getting a hint of the solution. I guess he must just be very attached to the idea that phenomenal consciousness is not adaptive. But then again many people get angry at the very idea that free will, love, religion, etc. are also adaptations or perhaps the by products of adaptation. Spoiler alert: all of this is merely implied by the truth of evolutionary theory. .


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