In Banff: Delia Graff Fara

Tuesday, February 20, 2007 at 05:37AM

The next Banff talk is Delia Graff Fara, on “Relative identity and de re modality.” She’s defending the thesis that material objects are identical to the matter of which they’re constituted. For example, the statue Goliath (G) is identical to the lump of clay Lumpel (L). She wants to allow that L = G, while having L and G differing in their temporal and modal properties. So, for example, in the future, a some more clay might become a part of the statue G, while not becoming a part of the lump of clay L. The original lump of clay is still present (and is joined by more clay), the original statue is still present, and is now larger. You can see why this is desirable: after the addition of more clay, there’s still only one statue there, and the old statue did not disappear only to be replaced by a new one.

Delia wants to preserve the truth of claims that statues don’t have all their parts essentially, while portions of matter do have their parts essentially, while holding that statues are identical to portions of matter. How can we do this? I find this kind of work interesting, but deeply difficult. Delia’s talk had a fair bit of relatively informal philosophy in it – it was a discussion of counterpart relations and such critters – and other participants followed the dialectic more closely than I did. I always get confused by this kind of problem. There are other talks at the workshop on quantified modal logic, which will hopefully give me some helpful ideas.