Monday, August 21, 2006

Defining presentism: the real problem

At the CMM event Robbie mentions below, Jonathan Tallant discussed a problem for defining presentism. The problem didn't seem to me to problematic, since it assumed the only existential quantifiers the presentism has in her toolbox are one equivalent to 'exists now' and one equivalent to 'existed, exists now, or will exist'. Since this is patently false, that problem seems to vanish.

But there did seem to me to be a problem in the vicinity; namely, that all obvious attemtps at a definition require us to reify times.

Intuitively I can refuse to admit the existence of times and there still be an eternalism/presentism question. Two theorists should be able to have a debate concerning the nature of time and existence without quantifying over times. But I couldn't think how to define the terms without reifying times, and certainly the familiar definitions fail.

Consider 'the only time is the present time'. If there are no times, this is true. So if there can be a presentist/eternalist debate between those who don't reify times, this doesn't capture presentism.

What about 'only present things exist' (where 'exists' here is atemporal)? Nope, that won't do if there are no times. Consider two endurentists who believe that the world started with A, B and C coming into existence. Those three objects proceed to endure through some changes, and then the world ends (taking A, B and C with it of course). So nothing comes into or goes out of existence in this world. At any time it is true that only the things that are present at that time exist atemporally, since A, B and C are the only things that exist at any time, and are the only things that exist atemporally. But that doesn't mean presentism is true at this world: intuitively, there is still a debate to be had between the two endurentists as to whether presentism or eternalism is true.

Any thoughts?


Anonymous said...

Hey Robbie,

I've also heard presentism defined as the view that no x bears any temporal distance to any y, where x and y are concrete particulars pulled from the most unrestricted domain of quantification available. Understood in this manner, if the presentist then takes x and y to be things like objects, events, facts, or what have you, and applies some preferred relationalist analysis of temporal distances, then it doesn't appear that she would be committed to the existence of times.

Also, regarding your last paragraph, couldn't the presentist just deny that A, B and C are the only things which exist during the world's history? Suppose that you think that in addition to objects and their properties, there exist states-of-affairs consisting of those object's instantiating their properties. Then you will also think that lots of things come into and go out of existence as A, B, and C undergo intrinsic change. Just a thought.

Ross Cameron said...

Ah - I see the view that Robbie and I are identical (and yet draw two salaries - hooray!) has reached the world at large. But are we necessarily or contingently identical? - there's the real question.

Let me deal with your second point first. Sure, I grant that if you think there must be other things in the world - such as states of affairs or events - then you can avoid the problem. But again, it seems surprising that you have to believe in those things in order to make sense of the presentism/eternalism debate. Shouldn't someone who only believes in ordinary concrete individuals be left with a question as to the nature of time and existence?

Now to your first point. I'm not sure I understand temporal distance. Suppose eternalism is true and we're in the A,B,C world. Take a time t. Is it true at t that A both bears zero temporal distance to B (since they are both present at t) and bears some positive temporal distance to B (since B exists at times which are not t)? If so, then I can see how to define presentism and eternalism without reifying times, but at the risk of making eternalism sound close to contradictory.

Robbie Williams said...

Ross: Why should that be contradictory? Suppose an eternalist says that A is at the following (distinct) temporal distances from B: d,d',d''...

Maybe this is labouring the obvious, but no contradiction ensues so long as you don't allow the inference from "X is at temporal-distance y to Z" to "for all w distinct from y X is not at temporal-distance w from Z". Maybe the problem is with the word "distance"? If so, we'll have to sit down and think of a new word!

(Of course, I guess all this will depend on what resources the relationist (say) is willing to give us in the way of temporal relations.)

Here's a thought. Looks like this approach won't be able to distinguish the following: a presentist world containing just a single instanenous object, and the limit of a series of eternalist worlds, shortening and shortening the interval for which an object exists. These two worlds look to be in some sense qualitatively identical, but maybe there's still some reason for eternalist/presentatist distinction: for example, in terms of what counterfactuals are true at the world.

That suggests one further way to construct "test sentences" that might address Ross's worries: take a characterization of eternalism in terms of the non-present objects, and then counterfactualize it, with the antecedent being something that both eternalist and presentist can agree is true. Something like the following should be true for the eternalist but not th presentist, in the world that Ross describes:

Were a cat to come into existence in two seconds time, then it would now be the case that: Ex (x is a cat and ~Present(x))).

Ross Cameron said...

Well I did say "close" to contradictory. Consistency is quite close :-)

I agree we won't get into inconsistency so long as we don't license the inference you mention: but I imagine people getting worried about being committed to 'x bears no distance to y and some positive distance to y'. Maybe that's just totally unfounded though.

So I take it the proposal is that presentism is the view that there is no x and y such that x bears some temporal distance from y, and not the view that for all x and y x bears no temporal distance to y, which the eternalist can agree with. I can live with that.

I had considered counterfactuals like that when talking to Jonathan about this, and I thought I could see a problem, but I can't remember it . . . I'll try to remember.

(Jonathan - do you remember?)

Robbie Williams said...

I agree that the inference does sound initially appealing, but my inclination is to think that the issue is merely verbal.

Some evidence: we hit exactly analogous issues in the spatial case. Think about what resources you'd have to appeal to to state the spatial relations (in a single dimension) between two spatially extended objects (at a given moment). Same issue: two touching spheres of diameter 1cm will be both zero distance apart, and 2cm apart.

A variety of tactics suggest themselves: appeal to min/max distance rather than distance simpliciter (but what about scattered objects?); appeal to distances between parts of the objects (but what if DAUP fails?). And so forth. All issues with analogues in the temporal case, I take it.