Tuesday, December 11, 2007

A New Version of the Identity Theory?

I'm reading Schiffer's Remnants of Meaning and its gotten me thinking about most (all?) physicalists' demand that mentalistic talk, and especially mentalistic ontology, needs to be reduced to physical talk and ontology somehow or other. My intuition is that most* mentalistic talk and ontology is itself physical in nature, and not because type-type or token-token or any such identity theory is true. I think my intuition is to accept the two premises of the following argument. I've never seen this before, but it's reminiscent of some of the discussion in Stoljar's "Two Conceptions of the Physical."

(1) For all x, if x is introduced to explain the overt physical behavior of paradigmatically physical objects, then x is a physical object.

(2) The special ontological commitments of cognitive science (mental representations, information processing mechanisms, etc.) are introduced to explain the overt physical behavior** of animals' bodies.

Therefore, (3) The special ontological commitments of cognitive science are physical objects.

I think the argument is also sound if we replace both occurrences of "special ontological commitments" with "novel linguistic forms (e.g. relations to mental representations)" and "physical objects" with something like "physicalistic linguistic form."

I want to call this an identity theory (maybe a bit cheekily) because (3) is, as far as I can tell, just what all identity theories have in common. It would be a new version because it is an identity theory no matter whether or how the posits and theorems of cognitive science are identical to various paradigmatic objects and theorems in and about the body.

Perhaps some won't like (3) because the posits of cognitive science lack spatial location, and aren't physical for that reason. I myself am willing to give up the intuition that something has to have a spatial location in order to be a physical object. If I weren't so willing, I would note that, as far as I can tell, nothing is lost by stipulating that these posits are located diffusely throughout the body.

Seriously, is this totally undefensible for reasons I can't see?
* - I tend to think phenomenal consciousness is fundamentally different. Let's restrict "mentalistic talk" and "mentalistic ontology" to the theory and ontology of cognitive science, narrowly construed.
** - Where "overt physical behavior" is taken to include some number of physiological states.


mandikp said...

One potential problem with the argument is that paradigmatically non-physical objects can be introduced to explain the overt physical behavior of paradigmatically physical objects.

At least one of Descartes's reasons for his belief in souls as unextended substances was that he needed an explanation of linguistic behavior and could conceive of no physical mechanism capable of holding up its end of an intelligent conversation.

An application of your first premise to Cartesian souls yields the contradiction that souls are both physical and non-physical objects.

iolasov said...

Thanks for the comment, "mandikp!"

That sort of example might ultimately prove impossible for the theory to handle. As (1) and (2) stand, the example certainly gives us a contradiction. There are ways to avoid this, though.

My first reaction is to change (1) a little bit, so that it reads:

(1`) "For all x, if it is reasonable to introduce x to explain the overt physical behavior of paradigmatically physical objects, then x is a physical object."

If we agree that Descartes' inference from the behavioral facts to souls was unreasonable, and that good theories in cognitive science are reasonable in the relevant respects, then (3) holds up against your objection.

(1`) is a bit more unwieldy than (1), though, isn't it? I prefer to avoid talking about reasonableness when I can. But I do think that getting from something like (1`) to (3) is a promising solution to whatever mental cramp got me thinking about these things - some sort of "mind-body problem." So if I need to bring in reasonableness to do that, it's fine by me.

mandikp said...

If you are going to follow a route through "reasonableness", then why not just take the following short-cut?

(1'') For all x, if it is reasonable to believe in the existence of x, then x is physical.

iolasov said...

Why didn't I think of that?