Wednesday, September 05, 2007

Hasker, sensible naturalism, and causal closure

From his essay "What About a Sensible Naturalism"


What would the naturalist have to accept, in order to accommodate the demands of reason at this point? At minimum, the naturalist must accept the existence of emergent laws—laws which manifest themselves in complex organic situations, and which result in behavior of the fundamental particles of nature different from the behavior predicted on the basis of the physical laws alone. To admit this is to reject the “causal closure of the physical domain” that is so dear to the hearts of many, perhaps most, contemporary naturalists. The naturalist will have to acknowledge that new causal powers emerge in suitably complex configurations of organic chemicals.—powers that are not evident in simpler situations, and are not deducible from any laws that operate in simpler situations. It will have to be true that, given a particular sort of brain-state, there supervenes, say, a desire to hear a performance of Beethoven’s “Moonlight Sonata,” and that, in virtue of this desire, certain actions, and certain bodily movements occur that could not be predicted merely on the basis of the physical laws that apply to the elementary particles making up the nervous system. A view that countenances the emergence of such causal powers might provide the basis for understanding mental states that could be effective in virtue of their propositional content. Many naturalists, however, will be extremely reluctant to abandon causal closure; if they do so, their status as naturalists in good standing could plummet alarmingly.

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8 Comments:

At 9/05/2007 10:23:00 PM , Blogger Blue Devil Knight said...

The 'sensible' adjective seems misguided. I would say 'spooky.'

Plus, it isn't clear what he is saying. These supposed emergent properties supervene on the physical, as he says. That is sufficient for causal closer, as I argued by reductio in my reaction to Arnold's strange naturalism here.

Here's another reductio. Assume X is emergent in his sense, such that X supervenes on the physical. Since X supervenes on the physical, all the causal powers of X also supervene on the physical. Therefore, there are no causal powers that X has which do not supervene on the properties of physical stuff.

For example, hardness is an emergent property. It isn't displayed by any individual molecules. It also has explanatory power. Hard things, for instance, can break windows. But that doesn't mean 1) That we can't give a microexplanation of hardness, or more importantly, 2) That the event of a hard object breaking a window can't be given an explanation in terms of the physical (e.g., in terms of the strains etc on the glass, where ultimately the forces are all local little forces from groups of atoms in the rock onto groups of atoms in the glass).

I am fine with the intuition that there are higher-level neural structures (e.g., field potentials) that can have "downward" influences in the nervous sytem (e.g., gross field potentials can influence the firing rate of other neurons, in a process known as 'ephaptic' influences [as opposed to synaptic]). But that doesn't mean it all isn't ultimately physical, and certainly does nothing to hurt the causal closure doctrine.

As for top-down causation, which I know Hasker (and his other new-breed materialist Christian cousins) is fond of, and I've written up a post providing many examples here. None of them imply the lack of causal closure. These new-breed Christian naturalists are simply not thinking clearly about emergence and top-down causation. I predict they will be an amusing anecdote in philosophy of mind books in 50 years.

 
At 9/06/2007 01:01:00 AM , Blogger Blue Devil Knight said...

Does Hasker ever hazard a guess as to the supervenience base of these emergent mental properties? Are they electrical in nature (e.g., large-scale electric fields in the brain, or perhaps distributed action potential ensembles), are they quantum fields (e.g., some kind of unified quantum superposition distributed across the brain), etc?? That is, is there anything specific into which we could sink our teeth? I don't recall anything specific in his book.

 
At 9/06/2007 12:11:00 PM , Blogger Blue Devil Knight said...

Umm, that second argument isn't a reductio, but just a straight-out argument. It assumes that if X supervenes on Y, then the causal powers of X also supervene on Y. This assumptions seems innocuous, thank goodness, upon a next-day reading (causal powers are just a subset of the properties of a thing, after all).

So, Hasker either needs to reject supervenience, or the claim that there are new causal powers (though he is somewhat slippery with the causal powers (in a way typical for the old-school emergentists)), talking about 'deducibility' of causal powers of X from the physical. Even if you can't reduce X to the physical in the sense of deduce X and its properties from the laws of physics, that doesn't mean X isn't physical (if that were true, then a virus would be nonphysical). That's the whole point of the move to talk of supervenience rather than reduction/deduction; if that weren't true we wouldn't need supervenience as a concept most likely).

 
At 9/07/2007 07:44:00 AM , Blogger Michael said...

Hi,

Sorry to jump in without being familiar with everything that has gone before. I'm not going to comment about emergence and supervenience and whether they exclude each other.

I just wanted to point out that if one understands "causal closure of the physical" to mean that all physical effects have physical causes, then it seems to me that the (supposedly) irreducible uncertainty of quantum mechanics already shows that some effects are not produced by physical causes. For example, there is no physical variable that tells you when the next radium decay event will be.

Am I missing something, or doesn't this mean that we already know that the physical causal network is "incomplete" or "open"? I know most physicalists don't think this way, but I don't see why not.

 
At 9/07/2007 09:19:00 AM , Blogger Blue Devil Knight said...

Note Victor just said that Hasker doesn't believe what he said, so replace 'Hasker' with 'Hasker's naturalist'.

 
At 9/07/2007 11:33:00 AM , Blogger Victor Reppert said...

Michael: Causal closure means that nothing over and above the physical can cause a physical effect. As a supernaturalist you might hold this position: that God performs miracles by sometimes guaranteeing that unlikely but quantum-mechanically possible events occur. God, strictly speaking, never does anything quantum-mechanically impossible, but chooses amongst quantum-mechanically possibilities to get what he wants done in the world. I think naturalists would want to exclude this. They will accept brute chance but nothing interefering from outside of nature.

 
At 9/07/2007 11:36:00 AM , Blogger Victor Reppert said...

Guminski and Draper both seem to aspire to be a sensible naturalist in Hasker's sense. When I get around to quoting the next paragraph from Hasker, I think it will become clear that Hasker thinks "sensible naturalism is a road out of naturalism. Neither Bill nor I think that it gets you all the way to theism all by itself, but it does lead to positions naturalists would very much like to get away from. (Idealism and pantheism are still there as options).

 
At 9/10/2007 11:43:00 AM , Blogger Michael said...

Thanks, Victor.

I just want to emphasize how it seems to me that quantum mechanics alters the landscape of possibilities with respect to supernatural causes.

If physics were classical (and deterministic), supernaturalists of any type could only assert that physical laws must be VIOLATED. Given the OPEN character of the quantum theory, supernaturalists are free to envision various supernatural causes that are CONSISTENT with physical laws (as far as we understand them today).

I'll add that the usual dismissal of indeterminacy in quantum mechanics as mere "randomness" is oversimplistic. For example, if you think of a superconductor as made up of electrons and nuclei (which it is), you cannot derive the occurrence of superconductivity. You have to "realize" that the electrons "condense" into pairs which behave in a qualitatively distinct way that is classically impossible: they flow without loss or friction. In general it seems to me that the randomness of quantum physics is usually associated with some kind of coordination...so it might not be right to think of it as purely random!

So, in quantum physics, God, or whatever extra-physical beings we contemplate, need not necessarily be reduced to just occasionally causing improbably events... I think this is one reason scientists get so touchy about mystical interpretations of quantum theory--i.e. because strictly speaking the physical theory doesn't rule it out!

(Incidentally, Searle has recently made the related point that saying the mere randomness of quantum mechanics is insufficient for free will is unwarranted...)

 

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