The Functional Approach

One avenue that is, in my view, open to the proponent of TWI is to say that the individual is a function that picks out different accidental properties at every world. Let us imagine that there is a set of functions F of which f is part that picks out the properties $,* and #, where these properties are true in a given world, 1,2 or 3.This approach was first talked about by Jaako Hintikka in his "Semantics for Modal Propositions". Now, we might say that the "individual" is this set and the members of this set are different proper names that refer to different properties in any given world. Ultimately this is an amalgamation of the approaches of Jaako Hintikka and Saul Kripke insofar as Kripke's origin thesis is understood to be analogous to what is characteristic of the members of F.

Here is an amusing picture of Leibniz by Anthony Hare. For more of Hare's wonderful drawings go to: http://www.siteway.com/illustrations_leibniz.php
(Thanks to Luke Ratzlaff for finding the site.)


The following are a series of pictures from a trip I took to Montreal for the 2006 Cognitio Conference on Situated, Embedded, Embodied and Extended Cognition. Unfortunately I was unable to get any pictures of the conference, but I did get pictures of some Montreal sites.


(This is the Montreal Museum of Fine Art)


(Extension of the Montreal Museum of Fine Art)

Completeness within a world and completeness across worlds: Trans-word identity

Much of the resistance to the trans-world identity of individuals has, in my view, much to do with the common conception of completeness within a world and completeness across worlds. That is to say, when we speak of a world, we tend to think that this world is,in some sense, a closed system: it has its own internalized space and time reations. These relations allow individuals to be traced through these coordinates. For example, we say that an individual person can be indexed to time and space coordinates, i.e. Leibniz @ t1 = Leibniz @ t50 without fear that this is incomplete. Adams and others think that so far as Leibniz feels at liberty to index individuals to times he should have no difficulty indexing them to worlds. While I agree with this intuition, I think an investigation into why time indexicals would seem so intuitive to Leibniz is in order before Leibniz's mistake in indexing them is pointed out.

Luke's Worries

Here is my reply to the worries Luke raised about Leibniz's time indexicals in the comments section. He says:"Yes, why is it so intuitive? We do seem to have a special day to day relation with time, or our concept of it."
Luke

I suspect the intuitive nature of Adams' rejection of Leibniz's time indexicals has to do with shifting the burden of proof. Adams wants to know why individuals should be indexed to times and not to worlds. That is, why should we say X @ t2 = X @t5, and view this move as legitimate without allowing there to be world indexicals, and thereby enable trans-world identity. It seems to me, in any event, that Leibniz would have done so because he thought that a world has its own temporal structures, and that these structures obviously do not extend out into other worlds. Whether or not this notion can be defended is what I think needs to be investigated. I am inclined to think that times are more like worlds than Leibniz would have thought and thus are complete in themselves; there is no unifying principle. Thus, when we time index we are engaging in a sort of trans-world indentification of individuals even though these individuals have clearly have different properties.