Wink's philosophy of time

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Jeremy and I pretty much share our philosophy of time, the so-called "consistent" theory of time I think it is called. As much as I like this theory and hold it to be true, there is one Achilles' heel to it that I can see. Imagine the following scenario:

In 2002, Alice receives a present from Bob. The present is a watch or some other suitably complex object that must have been man-made. Alice goes back in time to 2001. She meets Bob at some point and gives him the watch.

Dilemma: who made the watch? Notice that the watch only exists from the years 2001-2002. That's spontaneous creation and destruction of matter (which might be OK on quantum scales with elemental particles, but is not so OK large, complex items).

With the "consistent theory" of time, there is no praticular reason why such a scenario could not arise. ("Branching theories" can sweep this kind of problem under the rug along with any other "inconsistencies" that go along with personal timelines trumping world timelines.) My only out seems to be that time travel (in the backwards direction) is not possible.

Any thoughts?

[Edited to swtich names around so that the example makes sense now. Kudos to Jonathan for catching the mistake.]

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At my blog Parablemania, I registered my endorsement of the "time travel on a fixed timeline" view (which assumes eternalism), and my co-blogger Wink followed up by raising the question of unexplained causal loops (which are internally explained, but n... Read More

18 Comments

I would agree that time travel backwards is not possible. But I don't see the dilemma regarding the watch. After he traveled back in time and delivered the watch, she would then be able to have the watch indefinitely, even after 2002? He would still have to travel back in time at 2002 to deliver said watch. But through his travelling back in time (assuming he didn't then return to his own time) would that not create duplicates of both Bob and the watch? At least until 2001 Bob travelled back in time?
. . . never mind, I'm confused now.

I don't get it.

In 2002, Alice receives a present from Bob. The present is a watch or some other suitably complex object that must have been man-made. Bob goes back in time to 2001. He meets Alice at some point and gives her the watch.

Bob gives Alice the watch twice? When does he go back in time -- after giving her the watch in 2002? How can he give her the watch if he doesn't have it, having already given it away before beginning his time-travel?

No, I'm not sure he made the case clear. It's supposed to be of something that first appears because someone brought it back in time and then only exists until the moment it's brought back. The most disturbing example of this was from a Robert Heinlein story, I think from the 1950s. It involved a sex change operation, multiple cases of time travel, and someone being his/her own father and mother. The science, I think, wouldn't allow such a thing, but the philosophy of time I adopted in my earlier post and by David Lewis in the best paper on time travel ever written allows for this sort of thing. Here's someone who came into existence but was caused by nothing in the ordinary stream of things. This person's existence was caused only by future events, with time travel backward. But the time travel backward is dependent on the person's existence to begin with. So you have circular explanation and no ultimate explanation for why the person existed in the first place to be able to go back in time. The problem is basically that A is caused by B but B is caused by A. We've explained each of A and B in terms of each other, but we haven't explained the existence of the set of A and B.

I have something to say about this, and it's related to the cosmological argument, but I'll hold off a bit to see what anyone else might say. It's best to make sure we get the problem right before figuring out what to say about it.

Sorry, screwed up the names. Fixed them now. Go back and read the example and it should make sense now.

Ok, makes more sense now with the names changed. I see where you're going with it. I would have to argue that it's impossible for this to happen using your "consistent" theory. If the watch only existed in present time, because alice travelled back and gave it to Bob, who gave it to her, to take back to him . . . and on and on, then the watch could never has existed. I'd have to say that accepting this theory precludes any possibility of this situation arising.

The story is perfectly consistent, though. Wink's point is that consistency isn't enough reason to reject the story. There's no contradiction anywhere. There's just something with no explanation. Each part of the history of the watch is explained, but there's an unexplained whole.

Here's a different view of time: Time does not actually exist and is simply an idea created by the mind of man with no substance.

The illusion of time is created through movement, and in fact, every concept of time we use is based on the movement of some object. (day, month, year--plus assorted subdivisions...) Without movement, though, time has no meaning...

Going 'backwards in time' is therefore impossible since time doesn't exist, but you COULD achieve almost the same effect by 'backwards movement'--that is, every atom of the universe moves back to its exact previous location at a certain point in 'time'. Applied to the question in hand, then, since matter cannot be created or destroyed, the matter in the watch that's taken back in 'movement' along with your person doesn't violate any laws of physics, since the matter still exists through all points of time but just in a different location...

My URL field has a link to a related article I wrote about time and its application to religious questions...

Kevin, people have read both Augustine and Kant as taking views like this. I don't know enough about either to know if those claims are accurate. Most philosophers who take this sort of view today won't insist that there needs to be movement, but they do say there needs to be change.

There's a much easier way to have something like time travel on your view. As things are moving around as normal, someone seemingly miraculously appears out of thin air with a whole bunch of memories of things that haven't happened yet. This person claims to be a time traveler. Then this person proceeds to continue on as normal until dying. Two-hundred years later, a child is born, grows up, and lo and behold turns out to look just like that so-called time traveler, having the experiences that so-called time traveler claimed to have had, and so on. Then the person invents a device, calls it a time machine, and disappears, never to be seen again.

That all seems possible on your conception of time. My question is this. Is it better to see such a story as miraculous creation (and later annihilation) with the amazing coincidence of the person resembling the later one exactly? Or is it better to see it as the later event causing the earlier one and therefore legitimately calling it time travel. According to contemporary theories of causation, most philosophers say the latter is the obvious choice. You'd have to have a different notion of causation to resist that.

I've been trying to itemize the difference responses to Wink's puzzle. I think this is exhaustive, though it probably doesn't explore all the options within each:

1. Accept the static/consistent/B-theory/eternalist model of time. Accept that something can be completely unexplained. No problems. I believe David Lewis and Robert Heinlein would have been happy with this. I don't like it myself because I don't think something can have absolutely no explanation.

2. Accept the static/consistent/B-theory/eternalist model of time. Agree with Wink and me that you can't have something completely unexplained, so you have to deny this kind of time travel case. Resist Wink's conclusion that all time travel backward is impossible and say that only this kind is. Then you need a plausible explanation why some and not others. Can the metaphysical principle that says nothing be unexplained be enough to explain the difference?

3. Accept the static/consistent/B-theory/eternalist model of time but deny the possibility of backward time travel. This is what Wink seems drawn toward saying. My question is why we should rule all out time travel just because of one kind of case (running Wink's original argument in the other direction).

4. Deny the static/consistent/B-theory/eternalist model of time. Most metaphysicians today want to avoid this, since these views all conflict with our best science, which sees spacetime as one entitry with all points existing. I'm not sure how this will help anyway on some of the views, because on a presentist theory of time there's no past to travel to. Only the present exists. On a growing black theory of time, the past and present both exist, but if you travel to the past will our present continue to exist and move forward even though you're now in the past? Then the same problems as with the eternalist model arise, because what's now future for you exists. The only other way to do it is to wipe out all the intervening years once someone time travels, which would be a morally horrific adventure to go on given how many people it would kill. I don't like that version of time travel because I can't believe God would allow it. The only thing that might work is a branching model (which I haven't thought about much), but I can't even begin to think of how that fits with any spacetime models.

I don't know what is meant to be expressed by the sentence "nothing can be unexplained" and I don't know what it is that is not being explained in the case. I have a feeling that depending on how the sentence "nothing can be unexplained" is cashed out, either there will be a causal or natural law explanation of the mysterious thing or the metaphysical principle will entail the principle of sufficient reason, which is false. Either way the case ceases to be puzzling.

A lot of people claim to know that the Principle of Sufficient Reason is false, but I haven't ever seen a good reason why. We assume something like it in science, and the presumption is to continue believing it. In my experience, people who deny the Principle of Sufficient Reason (or similar principles) do so merely to get out of the cosmological argument, which of course begs the question.

I'm actually thinking more of a necessary explanation than a sufficient one, though. Finding a sufficient reason for A requires finding something that would guarantee A's existence. Finding a necessary reason merely requires finding something without which A would not have occurred.

I don't know how causal or natural law explanations could work here. The thing to be explained is the existence of the watch, which has a finite lifespan, came into existence because it traveled back in time, and traveled back in time because it came into existence mysteriously. It's a circle of causation. Each step might explain the later ones (or earlier in the case of the time travel), but nothing explains why there's a watch at all.

This argument is entirely parallel to the cosmological argument. Hume, Russell, and others complain that an infinite series of causes with no beginning doesn't need an explanation because each step is explained by the previous one. This is wrong, though. Each step is explained, but there's still no explanation for why there are any contingent things at all.

Some is now going on at my OrangePhilosophy link to this post, so I figured I should link to that discussion.

I you want to see a good argument against the principle of sufficient reason, see van Inwagen's "An Essay on Free Will". I very clear statement of the argument can be found in an article by Hud Hudson (either "Brute Facts" or "A true, Necessary Falsehood" (I can't remember which) both found in the Australasian Journal of Philosophy).

If you are seeking a necessary reason for the existence of the watch, and if a necessary reason is one that is such that if it were not the case, then it would not be the case that the watch exists, then I have such a reason. The reason is the causal circle itself. If the causal circle were not to exist, then the watch would not exist.

Your causal circle won't work as an explanation for the causal circle itself, though, and that faces the same problem. Not just any necessary condition will serve as a necessary explanation. I don't see how anything can explain itself unless it's a necessary existent.

As for PSR, I'm not familiar with Hudson's work on it, but van Inwagen just argues that PSR is inconsistent with anything's being contingent. Leibniz strongly disagreed, and I've posted at OrangePhilosophy about one way to defend Leibniz on this. The crucial point is that van Inwagen assumes only one kind of possibility, necessity, and contingency. One way to use that is in that post. Another that has occurred to me since is to see contingency, necessity, and possibility with respect to something, sort of as David Lewis' new version of post-Kripkean anti-essentialism does.

The other issue is that you don't need PSR to have a principle calling for an explanation more significant than the trivial explanation of a contingent thing by its own existence. William Rowe shows this in his book on the cosmological argument. He doesn't ultimately like anything he comes up with, but he shows how rich the conceptual space on this issue is. John Hawthorne and Andrew Cortens published a paper called "The Principle of Necessary Reason" in Faith and Philosophy sometime in the 90s that gave a cosmological argument with something that seems to do the trick as far as I can tell. The same sort of principle will work here.

I am acquainted with the principle of necessary reason. I was assuming such a principle when I gave my solution in the last post. Given that "the thing to be explained is the existence of the watch", I believe that the solution given is correct. However, if the question is what explains the existence of the causal circle, then I have a different answer. I believe that if there was not an instance of time travel, then there would be no causal circle. Thus I tentatively suggest that the necessary reason that explains the causal loop is the presence of time travel.

It seems that you post on PSR simply accepts the conclusion of van Inwagen's argument and accepts that there is no metaphysical contingency. I agree that if there is no metaphysical contingency, then PSR can be saved. Spinoza seemed to believe something similar. He suggested some kind of epistemic concept that could be used in place of metaphysical contingency. Similary, you seem to suggest a mere logical possibility that may be used in place of metaphysical contingency. I find these suggestions unacceptable. I do not believe that mere logical contingency can account for certain truths which can be accounted for by way of metaphysical contingency. There are several sets of metaphysically incompatible statements that are not logically incompatible. For example:

P1: George is red all over.
P2: George is green all over.

I claim that the incompatibility of these two propositions cannot be accounted for by way of mere logical modality.

I don't know why you think P1 and P2 are incompatible. If time travel is possible, as we've been assuming all along, I can be red all over, become green all over, and then travel back in time so that I'm both red all over and green all over at the same time.

I know this is a cheat, because you can just add 'at the same place' or something like that, but this makes it a lot harder to come up with things that seem metaphysically but not logically impossible. Still, I felt compelled to say it.

I'm not sure how this example is relevant, anyway. It shows that some set of sentences is mutually incompatible without being logically inconsistent. How does that show that there are things that are metaphysically contingent in an absolute way (such that God, for instance, would have no choice about them but that they're still not necessary)? Showing that something is impossible doesn't show that anything else is contingent. [It's the thing in the parentheses, by the way, that I find intolerable.]

You're right. My example does not show that there is metaphysical contingency. Though I do believe that it provides a little support for that claim. Here is how. P1 and P2 (properly modified) show that there is a necessity that is more narrow than logical necessity. If there is such a necessity and we know it, then there is some reason to believe that there is a corresponding possibility and contingency. That is, we have some reason to believe that there is metaphysical contingency. I know this is not very good.

Right now I think that a case might be made from the fact that humans are morally responsible. It seems that a necessary condition of moral responsibility for an action A is that it is metaphysically possible that a person not perform A. That is moral responsibility is incompatible with metaphysical necessitarianism. I'm sure that you don't find this very persuasive though.

I can't think of anything better off the top of my head right now, but I'll think about it. It might take me a while to respond though because I'm traveling and I have little access to computers.

You're right that I don't think moral responsibility shows anything about necessitarianism, because I'm a compatibilist. I don't think absolute metaphysical possibility is at all required for moral responsibility, for either us or God.

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