Thursday, October 08, 2009

Anti-Extensionalists?

We have had the first session of the new LOGOS Reading Group on Metaphysics. We discussed Varzi’s recent ‘Universalism Entails Extensionalism' in Analysis. I was quite surprised to learn about the difference between characterizing a sum of the Xs as
something that overlaps all and only those things that overlap some of the Xs
vs
something that has the Xs as parts and no part disjoint from the Xs.

We also resumed a discussion we had last year about who should count as anti-extensionalist, allowing that there be two non-atomic things sharing all proper parts. Varzi mentions Wiggins 1980, but as Marta Campdelacreu pointed out, for a Wigginsian arguably the head of the cat is part of it, but not of a ‘mere’ fusion of its body cells, right? Any other candidates?

4 comments:

Pablo said...

For those of us who were not present, could you please elaborate on the doubts about why Wiggins should count as an anti-extensionalist? Could he really claim that the head of the cat is part of the cat but not of the lump of feline tissue that constitutes the cat (or the ‘mere sum of cat cells’, as you put it)? Here is a brief argument against this possibility: it seems plausible that there is a set of things, some cells, that fuses into both the cat and the lump –so both the cat and the lump are made of exactly the same cells. It also seems plausible that every part of both the cat and the lump is made of some of these cells. But then, given Strong Suplementation, the cat is part of the lump and vice-versa. (Something that, if I remember correctly, is accepted by Thompson, in her defense of a Wiggins-like position…this comes with a rejection of the principle that if x and y are both part of each other, then x=y). And then, by transivity, the head of the cat is part of the lump and so anti-extensionalism as characterized by Varzi is not avoided…the cat does not have any parts that the mere sum lacks. ---

Dan López de Sa said...

I don't know much about Wiggins, Marta might elaborate. Just a quick question: How does the argument from Strong Supplementation against Antisymmetry go?

Pablo said...

Strong Suplementation tells you that if the cat is not part of the lump, the cat has a part that is disjoint from the lump. Now, suppose for reductio that the cat is not part of the lump. Then, which part of the cat is disjoint from the lump, given the “plausible assumptions” I mentioned? It cannot be one of the cells, because each cell is part of both the cat and the lump. It cannot be one of the bigger parts of the cat, like the head, because the bigger parts are also composed by some of the cells that compose the lump. So the cat must be part of the lump after all. And for parallel reasoning, the lump is part of the cat. In order to keep the Wigginsian view that the lump and the cat are non-identical, one has to reject anti-symetry. I hope I am not confused :)…

marta campdelacreu said...

Hi all,

about Pablo's first comment: if I understand you well, your argument pressuposes that objects are identical to fusions of other objects (cells, atoms or whatever) but is this assumption a plausible assumption from a Wiggins-style framework?

The same for the Strong Supplementation principle.


about Pablo's second comment: even accepting the Strong Supplementation principle, could not defenders of "constitution is not identity" say that the cat has the following part : a sortal-component (in the style of Koslicki 2008) which it does not share with the piece of feline tissue out of which it is made? What do you think?


Marta