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Thursday, September 28, 2006

Tensing the Copula

Last night I re-read David Lewis' Tensing the Copula. The article is a reply to two solutions to the problem of temporary intrinsics.

The problem of temporary intrinsics is this. Material objects, like you and me, have different properties at different times. At t1 Brit is bent-shaped, and at t2, she is straight-shaped. But if the properties of being bent-shaped and straight-shaped are had simpliciter and they are really properties and not relations, then 'at t1 Brit is bent-shaped' must entail that Brit is bent-shaped. And 'at t2 Brit is straight-shaped' must entail that Brit is straight-shaped. So, Brit is both bent-shaped and straight-shaped!

Lewis first considers Mark Johnston's solution. Johnston suggests that the copula is temporally modified. So, 'at t1 Brit is bent-shaped' translates as 'Brit instantiates-at-t1 the property of being bent-shaped', and 'at t2 Brit is straight-shaped' translates as 'Brit instantiates-at-t2 the property of being straight-shaped'. Lewis dislikes this proposal because it does not account for how we can have properties simpliciter. Brit does not have the property of being bent-shaped. She has-at-t1 the property of being bent-shaped.

Sally Haslanger suggests that the proposition that Brit is bent-shaped is true at some times and false at others. Lewis replies that this proposal presupposes endurantism (i.e., the view that objects persist by being wholly present at different times). However, I think he is wrong about this. The proposition expressed by the sentence 'Brit is bent-shaped', relative to a context, contains the referent of 'Brit'. If endurantism is true, the referent is a three-dimensional enduring object. If perdurantism is true, the referent is a worm. It can still be true with respect to one time that Brit -- the worm -- is bent-shaped, and false with respect to another time. All it takes for the worm proposition to be true at t is that the relevant t-part of Brit is bent-shaped.

The temporal propositions solution does not presuppose endurantism. Rather, it is neutral in disagreements among different metaphysical proposals. And that I take to be a virtue of Haslanger's proposal. The problem of temporary intrinsics can be solved without taking sides!


Mike said...

Hi Brit,

Can this be true?
"All it takes for the worm proposition to be true at t is that the relevant t-part of Brit is bent-shaped."

Aren't there properties of temporal slices of you that are not properties of you? For instance, a temporal slice of you has the property of not being identical with every slice of you (or, the "worm"), but you don't have that property. So the fact that a part of you at t has P does not seem to entail that you have P.

Brit Brogaard said...

To determine whether the temporal propositions account is correct or not (assuming the worm theory), let us look at a particular case.

'Brit is not identical to every slice of herself'

That seems true. And that is what the account predicts. For no part of me has the property of being a thing x such that x is identical to every part of itself.

What about:

'Brit is composed of multiple temporal parts'

The temporal proposition that Brit *is* composed of multiple temporal parts comes out false. But that is as it should be. For I never claimed that my account should be extendable to sentences that are true in Ontologese. I am only claiming that the temporal propositions account make the correct predictions in English (the temporal propositions account is, after all, metaphysically neutral). To account for sentences true in 4D Ontologese, we need eternal propositions.

Mike said...

You were arguing that Haslanger's position is consistent with 4D or perdurantism, right? So I thought that, for the sake of showing this, you were assuming 4D. I think that's right. But then you urge that this proposition is false.

"Brit is not identical to every slice of herself"

True, you're not identical with any slice, but I thought you'd be identical to every slice. Or, no?

Brit Brogaard said...

Well, actually you need not be identical to every slice, not even if 4Dism is true. If Sider is right, then composition is not identity. So, if 4Dism is true, then you are composed of your slices, but you're not identical to them.

I guess my position is this. Haslanger's temporal propositions view is consistent with 4Dism. But it need not account for all the truths that the 4Dist is committed to. If temporalism is true, then there are temporal propositions but temporalism does not rule out that there are eternal propositions as well.

Consider, for instance, 'Socrates exists'. On one reading, it expresses a (currently) false temporal proposition. On another, it expresses a true eternal proposition.

I took Lewis' initial puzzle to be to account for change without modifying the predicate in 'A is F' and 'A is not F'. One modifies the predicate if one attaches a 'at t' to either the copula or the adjective. But the temporal propositions view does not do that.

Andrew Bacon said...

This is very interesting.

But can't you run a Lewis style argument against propositions changing with the predicate 'is true'. Applying the same solution to this will always result in a new problem ending up with something a bit like McTaggarts regress.

Brit said...

Hi Andrew,

So, I take it that your idea is this. The following is a meta-linguistic change-description:

'The proposition that John is bent-shaped is true at t1 but false at t2'. But if sentences of the form 'the proposition that John is bent-shaped is true at t' entail 'the proposition that John is bent-shaped is true', then the puzzle is up and running again.

But here I think I will shift the burden of proof. Give me some reason to think that 'the proposition that John is bent-shaped is true at t' entails 'the proposition that John is bent-shaped is true'.

Andrew Bacon said...

Right, so I take it you're rejecting the idea that truth can be had simpliciter, as an intrinsic monadic property of propositions (at least as far as temporal propositions are concerned).

In which case I agree that Haslanger's solution doesn't take sides between endurantism and perdurantism. But a few words in defence of Lewis - I don't think this was what he was claiming. I took his remarks to be saying that Haslanger's solution left the notion of an enduring thing bearing an intrinsic property at a time unexplained. It would be useless to explain an object changing its intrinsic properties by appealing to propositions which change their truth value. Which truth value our proposition has is explained in terms of whether an object has the intrinsic property in question at a time.

If you are right and the perdurantist can consistently talk about propositions changing truth value then the perdurantist has an explanation in terms of the relevant t-part. The endurantist on the other hand doesn't have this.

Brit said...

That's right. Neither temporal propositions nor eternal propositions are true or false simpliciter (temporal propositions are true or false relative to worlds and times, eternal propositions are true or false relative to worlds). However, utterances are true or false simpliciter.

"it would be useless to explain an object changing its intrinsic properties by appealing to propositions which change their truth value"

Unless facts just are true propositions (i.e. facts about worlds at a time are temporal propositions, etc.)

But if they are not -- if facts are not simply true propositions -- in that case, I think you are right.

Ocham said...

The argument appears to be

1. At t1 Brit is bent-shaped, and at t2, she is straight-shaped.
2. The properties of being bent-shaped and straight-shaped "are had simpliciter and are really properties and not relations."
3. But that implies something is bent-shaped and straight-shaped!

Can I offer an old-fashioned solution to this, proposed by Abelard (12th century) and Ockham (14th century) among others. There is a contradiction in being, now, straight-shaped and being bent-shaped. But clearly it is possible that Brit is (now) straight-shaped, but was (some time before) bent-shaped. These arguments all rely on getting some past tense statement into the present tense, in order to generate contradiction.

Premiss 2 seems designed to get us there, but I don't see how that does the trick. How does the idea that properties "are had simpliciter" get us to Brit being bent-shaped now as opposed to bent-shaped before?

Brit Brogaard said...

Yes, that is neat! I suspect this solution is going to be similar either to Haslanger's temporal propositions solution or to serious tensing (the tenses are irreducible). Either move will block the argument. I didn't know Abelard and Ockham already suggested this. Very neat!

Ocham said...

Perhaps I could point you in the direction of my Logic Museum, in particular my translation of chapter 7, book II of Ockham's master work, the 'Summa' of Logic.

Also in the Museum you can find the 'eternity section'. Do have a look at the Augustine piece from the Confessions. He says 'Neque id quod futurum est esse iam, neque id quod praeteritum est'. Neither that which will be, nor that which is past, exists now. Why? Because 'si nihil praeteriret, non esset praeteritum tempus, et si nihil adveniret, non esset futurum tempus' - if nothing passed away, there would be no past time, and if nothing were arriving, then there would be no future time. Seems to be an early definition of Presentism (and a very persuasive one at that – if nothing ceased to exist, or came into existence, how could there be time at all?).

The basic premiss behind the Museum is that all current philosophical questions have been discussed at least once before in history, and that we are doomed to repeat history forever unless someone like myself posts all the previous discussions on the Internet, which fortunately we can now do, since unlike medieval times we now have an internet. When philosophers realise this they will give up and do something more useful, like working in a call centre.