Friday, August 01, 2008

My immaterial Twin

Some people believe that the shapes of material objects are extrinsic. Kris McDaniel, for example has argued for this conclusion with an argument that involves a kind of Humean principle that bars necessary connections between the intrinsic features of distinct contingent entities. It is difficult to formulate such a Humean principle well and I have worries about McDaniel's formulation. But, let me set those worries aside for now and briefly restate his argument.

According to McDaniel, and most of us, material objects and the regions they occupy are distinct entities that stand in an occupation relation to one another. It turns out that the shape of a material object must match up with the shape of the region it occupies. But, if the shapes of both material objects and regions are intrinsic, then that means that there is a necessary connection between the intrinsic features of these distinct (contingent). This connection is barred by the Humean principle alluded to above. So, either the shapes of material objects or the shapes of the regions they occupy are extrinsic. McDaniel, and others, take it that the shapes of regions are intrinsic. In the near future I will question this premise (but not now). granting this premise we must conclude that the shapes of material objects are extrinsic.

That is, roughly, how the Humean argument for the extrinsic account of the shapes of material objects goes. Although, I don't think this argument is sound, let me assume for the moment that it is and present an interesting argument involving the extrinsic account of shapes.

Many people accept a Lewisian account of intrinsicality according to which intrinsic properties of particular objects are properties taht never differ between the duplicates of those objects. This is yet another principle that needs to be more carefully formulated. I have not come across a satisfactory formulation in the literature. But, for the sake of this argument, let me try to come up with one. Let's try this one:

(LAI) Nec, for any x and any F (x is F intrinsically iff (for any y that is a duplicate of x, y is F as well).

For simplicity I'll just take the quantifiers in this formulation to be possibilist and I'll pretend that counterpart theory is true (the principle can be ammended to avoid these commitments, but it only obscures the issue I want to get at).

As I said above, this kind of Lewisian account is accepted by many philosophers including McDaniel (though I'm not sure he'd accopt my formulation). But, (LAI) in combination with the extrinsic account of shapes leads to a rather surprising conclusion. It seems that if shape properties are extrinsic properties of material objects, then the property of being shaped is also an extrinsic property of material objects as well. Moreover, I am a material object and I have a shape. But, it follows from (LAI) and the claim that my shape is extrinsic that I have a duplicate that is not shaped at all. But, if something has no shape whatsoever, then it is not spatially located and hence immaterial. So, I have a duplicate that is immaterial. But, any duplicate of mine presumably has consciousness. So, there is a (perhaps merely possible) conscious duplicate of me that is immaterial.

That seems to me like a rather radical conclusion. I'd like to see if I can get an even more radical conclusion. I thought I might be able to argue for dualism. But, I'm not sure how to proceed from here.

3 Comments:

Blogger Andrew Cullison said...

I want to Sympoze this - may I?

5:40 AM  
Blogger Joshua said...

sure

1:58 PM  
Blogger Alex S. said...

I just stumbled across this blog; it's great! A couple of comments.

First, it's not obvious to me that, if determinate shape properties are had extrinsically by material objects (if it is a fact), then the determinable property having a shape must be extrinsic, too. For it's not obvious to me that, in general, a determinable is extrinsic if any (or even all) of the determinates of that determinable are. I'd need to see at least some motivation for this principle.

Second, the right-to-left conditional of (LAI) is false. Counterexample: Let F be the property being identical to Bob Dylan; though not every duplicate of Bob Dylan has F, clearly this doesn't entail Bob Dylan doesn't have F intrinsically. Another counterexample is the property being a modal counterpart of Bob Dylan.

One way to avoid these types of counterexample, of course, is to restrict (LAI) to purely qualitative (non-haecceitistic) properties. But that seems a little ad hoc. Moreover, it's not hard to think of counterexamples that are purely qualitative; they're just harder to state.

Third, (LAI) is an account of intrinsicality only if we can define 'duplicate' without recourse to the concept of intrinsicality. Lewis of course thought we could: by defining 'duplicate' in terms of perfectly natural properties and relations. The account that Lewis actually provides is much closer to this:

(LAI*) Necessarily, for any x and any F (x is F intrinsically iff (for any y that has the same pattern of distribution of perfectly natural properties and relations over its parts as x, y is F as well)

Substituting in (LAI*) for (LAI), assuming that Kris is right that shape properties are had extrinsically by material objects, and in particular the property having a shape, then all that follows is that there is possible conscious being with no shape yet the same pattern of distribution of perfectly natural properties and relations over its parts as you. But if (as many assume) the perfectly natural properties and relations are expressed by the predicates of fundamental physics, then it's not clear to me that there is a conscious duplicate of you that is *immaterial*. Things with mass, charge, spin, and so on sure sound like material things to me.

3:28 PM  

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