[ExI] Is the brain a digital computer?

[Dan]

Forgive the top posting.

I think most self-identified materialist are really physicalists and that the difference between the notions is minor. To me, physicalism just means, in terms of mind, that mental processes _supervene_ on physical ones.

I'm not sure this supports dualism or what you mean by a dualism that would be supported by it. I know there are non-reductive physicalists, such as Louise Antony and Josephy Levine (or they were a few years ago when they published an essay defending this position against the likes of Kim:). Is that dualist? They don't seem to think so -- save that they seem to mean mind has a domain of autonomy, but what does that mean in ontological terms?

A problem for the dualist-physicalist is that the core tenet of physicalism is that the physical world is causally closed. This means that physical whatever -- things, events, etc. -- can only have physical causes. (This would amount to any seeming non-physical cause really being a physical one ultimately.*) How would dualism of any sort stand up to this? It seems once one introduces non-physical causes, one is giving up physicalism all together.

I'm not sure computers captures dualism well. It's nice metaphor, but I doubt any serious dualist would see it as more than that. After all, computer programs can be reduced to how electrons are moving about. (Someone here mentioned multiple realizability. I don't think that works either. Antony and Levine seem to disagree on this, but I think their argument against Kim here, while it probably does knock out part of the latter's reasoning, doesn't really knock out the conclusion.**) I thought dualism, to be worth its salt, would have to have more than one set of things, events, properties, etc. merely supervening on another set -- as in mind supervening on brain or the mental supervening on the physical.

In his _Physicalism, Or Something Near Enough_, Kim presents a fairly strong case for physicalism with almost no non-reductive things, properties, etc. His argument is basically if all the mental stuff is really just physical stuff because all mental causes are, ultimately, reducible to and supervene on physical ones. In his terms, let's say you have two mental states, where it appears one causes the other:

M1 -> M2 (i.e., M1 causes M2)

and underlying two physical states, where one causes the other:

P1 -> P2 (i.e., P1 causes P2)

M1 one really supervenes on P1 and M2 on P2, so then we could say:

P1 -> M2 as P1 -> P2 and there is no M2 without P2.

Add to this causal closure under physicalism and there's no need to posit M1 -> M2 -- since there are and could be no non-physical causes for P2. I.e., per physicalism, so M1 can't have any causal input to P2. Does this make sense?

Regards,

Dan

* This can get complicated depending on how one limits "physical." Obviously, if one expands it out to include everything now thought of as mental, then one gets physicalism by definition. But if one has too narrow a delimitation of physical, one might end up thinking QED effects are not physical and hence chucking out physical on the basis of post-QED physics.

** Of course, I've often wondered how the multiple realizable argument fits in with Paul Benacerraf's views of set theory's relation to number (as in his "What numbers could not be") and with Lionel Robbins views on non-reducibility of economic laws (as given in the first edition of his _Essay on the Nature and Significance of Economic Science_).


From: The Avantguardian <avantguardian2020 at yahoo.com>
To: ExI chat list <extropy-chat at lists.extropy.org>
Sent: Fri, February 26, 2010 5:27:41 PM
Subject: Re: [ExI] Is the brain a digital computer?

----- Original Message ----
> From: Dan <dan_ust at yahoo.com>
> To: ExI chat list <extropy-chat at lists.extropy.org>
> Sent: Fri, February 26, 2010 11:46:07 AM
> Subject: Re: [ExI] Is the brain a digital computer?
> 
> Maybe I'm getting the wrong view from reading his work, but my view is Kim is a 
> materialist or a "physicalist" -- which seems to me to be a euphemism for 
> materialist. I get this from, e.g., his _Physicalism, Or Something Near 
> Enough.

I think that physicalism is a bit more robust than simple materialism. Physicalism allows for all of physics to come to play in the philosophy of mind. This includes concepts like energy, information, and entropy. Things that are distinctly not matter. So in a way physicalism is more supportive of a dualistic worldview, especially when QM is concerned. Since a non-superstitious irreducible dualism is at the heart of measurement problem. Of the prevailing opinions on the matter either an observation by a mind collapses a non-material wavefunction *or* an observation by a mind creates whole new universes out of nothing.

> That said, though, I don't think the dualist 
> position is necessarily religious. To me, there are just many different views 
> one can have walking into this issue. Dualism happens to be the view many take, 
> but I don't think they take it for religious reasons -- meaning, they hold it on 
> faith. Rather, I think it's just a default position for 
> many.

I don't think dualism is necessarily religious either. Indeed I don't see how computationalism can avoid being a dualist philosophy. I mean computers have hardware and software and those distinctions are every bit as dualist as body and mind.

Stuart LaForge 

"Never express yourself more clearly than you think." - Niels Bohr