Growing Individuals

From a purely selfish point of view, one of the exciting things about Sally Haslanger’s Persistence Through Time is that it gave me an opening to talk about one of my old pet theories. In current terminology, I claimed that there is no one theory of persistence, rather there are different theories of what it is to have a past and what it is to have a future. This could get long, so it’s going in the extended entry.

Assume for now an ontology of temporal parts (or temporal coincidents, it won’t really matter) and unrestricted mereological composition. In such a world, which things are the tables, chairs and beer mugs, the ordinary objects that we talk about, think about and quantify over?

David Lewis’s answer is that they are space-time worms: fusions of past, present and future temporal parts. This leads to a simple account of (simple cases of) tensed predication. I was in DC last year is true iff I have a temporal part last year that was located in DC.

Ted Sider’s answer is that they are stages, individual temporal parts. This leads to a more complicated account of tensed predication. I was in DC last year is true iff I have a temporal counterpart that was located in DC.

Both theories allow for the fact that what looks like a single material object can be associated with different persistence conditions. On Lewis’s theory, “that statue” can pick out a different 4D worm than “that lump of clay”, even though those worms share a current temporal part. On Ted’s theory, those phrases may trigger (i.e. make contextually salient) different counterpart relations even though they are co-referential.

Ted has many arguments for his theory, one of which is the argument from temporary intrinsics. Consider a balloon that is currently blown up and hence (roughly) spherical. Intuitively (says Ted) it is intrinsically spherical. Since Lewis says similar things elsewhere, he hardly has standing to disagree. But on Lewis’s theory, the balloon itself is not intrinsically spherical. Rather, it intrinsically has some four-dimensional shape, and it has the relational property of having a(n intriniscally) spherical temporal part at the time simultaneous with us. That seems bad, so we have a reason to think that the balloon itself is the current temporal part, not the worm.

Sally Haslanger noted that Ted’s theory does not allow for what she calls history-dependent intrinsics. Her examples are contentious, but it’s clear that there are some uncontentious examples around. The balloon is a shape-changer, it has had several different shapes over its life. (It certainly wasn’t spherical in uninflated mode.) Other things are (at least approximately) shape-constant. The Sydney Harbour Bridge has not changed shape significantly over the course of its life. The difference between being a shape-changer and a shape-constant seems to be an intrinsic difference. But on Ted’s theory which of these properties one has depends on which counterparts one has, and hence these properties seem to turn out to be relational and (probably) extrinsic.

Ted agrees that this is a good argument against this argument for his view. (He still thinks the other arguments he has work, so he still believes his view.) But Ted suggests (or at least did suggest at the APA Eastern symposium) that we are now left with stalemate. There’s an argument from sphericality for his view and against Lewis’s, and an argument from shape-changing for Lewis’s view and against his. Deadlock. Dropping the assumption of the temporal parts metaphysic won’t help, because the endurantist position seems to have the same costs and benefits as Lewis’s theory.

That last point will probably be controversial, so let me expand on it a little. It’s instructive to look at the name Haslanger chose for her problem making concepts: history-dependent intrinsics. Note not future-dependent intrinsics, but history-dependent. I think this is relevant because I think there are history-dependent intrinsics but not future-dependent intrinsics. Consider the following asymmetry.

Depending on when you pick its date of birth, the Sydney Harbour Bridge is roughly 72 years old. This seems to be an intrinsic property of the bridge. It’s a property of the bridge itself as we might say. Temporal duration into the past is a matter of intrinsic quality.

In this world the bridge will last hundreds more years. But in a distant possible world it is blown up by terrorist attack next year. It seems that the bridge that is blown up could be intrinsically just like the actual bridge that will last for centuries. So how long the bridge will survive is an extrinsic property of the bridge. Temporal duration into the future is a matter of extrinsic quality.

There’s an asymmetry here that seems like it should be accounted for. And neither Ted’s theory, nor Lewis’s theory, nor the endurantist theory can account for it, because all three theories treat the past and future symmetrically. But the asymmetry can be handled if we mix Lewis’s theory and Ted’s theory. Say that ordinary objects are fusions of past and present temporal parts, but they have no future parts. Objects survive into the future by having future counterparts, just as Ted says. Then we get the right result that temporal duration into the past, but not the future, is intrinsic. We get the result that being a shape-changer over one’s past life is intrinsic. (And note that’s all the data supports. If the Bridge will have twenty new lanes added next year that would not undermine our claim that it is now intrinsically a shape-constant.) Provided it’s intrinsic what one’s last temporal part is (a presumption about which I’m a little nervous) it also turns out that the balloon is intrinsically spherical (i.e. spherical at its last stage.)

I go into this all in much more detail in Growing Individuals and Intrinsic Properties, a paper which seems to have fallen onto my inactive pile. If you want to develop the idea, feel free, but do give me credit!