Michaelson

Well doesn't that all hinge on the question of canine identity? M and M* aren't physically identical -- M* has shed a few extra hairs etc -- but that is not to say they're not what we would consider the same dog. M* would not be physically identical with M even if he had not been sent back in time, but we would still say that they are the same.

In my first year metaphysics reading David Lewis suggested you think of M's life as something like a rope twisted around on itself. It's the one rope, but different temporal stages of it can exist in the same location. Consider M's life as a spatio-temporal streak twisting back on itself and it is hard to see the contradiction.

acronos

I did pretty much the same thing. My date was in July 1995. I promised myself that I would leave a message to myself on that date. Since I recieved no message, I have since quit putting much mental energy into time travel. Honestly I am shocked to discover someone else who has done the same thing. However, it is possible that you and I are the first cycle through or that it was outlawed before I was able to carry out my promise. I will keep my promise to myself if the time arives - even though I suspect that I will no longer be me if I do so. My conclusion is that time travel is very unlikly in our lifetime, and I expect to live to be very old.

mnkbdky

Let's consider what being a thing qua spatio-temporal stages my look like and if this could resolve the contradiction inherent in time travel.

As I see it there are two ways of interpreting what a spatio-temporal stage might look like. First, we could have some Buddhist/Humean bundles or, secondly, we could have an Aristotelian substance.

Now, I take it that Aristotle believed that some sort of unified substance supervened when individual parts worked together for an end and, thus, are considered to be one thing. Therefore, whether or not parts were interchanged as long as it still functioned toward its end it was still one thing. That is, as long as it was functioning toward its telos it would still have the emergent property of oneness. Whether or not this is a coherent idea it should still be thought that A=A, thus, the contradiction would still result in time travel.

The Buddhist/Humean bundles is different a case. It seems that conceptually this might work. However, upon further scrutiny we discover that the view is necessarily false itself and, thus, cannot be considered a solution to the contradiction.

Here we must employ the rule that if something is possibly necessarily false, then it is actually necessarily false.

Buddhist/Humean bundles are possibly necessarily false, therefore, Buddhist/Humean bundles are actually necessarily false.

Why are they possibly necessarily false? Consider this: according to Buddhist/Humean BH thought A continues the existence of B if and only if B is in a proper causal relationship R with A (with Hume this should actually be proper temporal sequence T since causation was not properly part of his hypothesis). What R is I am not exactly sure about. However, what ever you believe it is just insert it. Really the argument applies to all. Now, it is not inconceivable that two things may result from one cause. Therefore, let us say that A causes both B and B*. Now, according to BH both B and B* would continue the existence of A. That is both B and B* are A. However, this is impossible.

Let us imagine a machine that duplicates things through the process of R. We place A in and by R the machine makes a duplicate B of A. The machine has a flaw, though, and A is annihilated in the process. Could we say B continues A existence? Now, let's say we work on the machine and now it makes two copies of A, namely, B and B*. Still the machine has the unfortunate consequence of annihilated A. However, a third machine is made and the unfortunate result is fixed. We stick A in the machine and by R it produces both B and B*. The condition of R has been met, yet, there are three items, A, B and B*. Now clearly B=/B*. How is it then that B=A and B*=A? Is this even coherent? Can two separate things be equal to one? It does seem to be so. That is, if B=A and B*=A, then, B=B*. However, it is clear that B=/B*. Therefore, B=/A and B*=/A.

Now because it is possible that cause A have two results, namely B and B*, it is impossible that R be sufficient to maintain identity because A's having two results results in a contradiction when it comes to maintaining identity. The only way to maintain identity is if no change occurs, at least in something’s essential properties.

Since, then, it is possibly necessarily false that R maintain identity it is actually necessarily false that R maintain identity. Something that is necessarily false cannot be used as a possible solution to a problem. Thus, BH cannot be used to solve the contradiction in time travel.

It seems that this spatio-temporal stages STS is some sort of BH and, therefore, STS cannot be used as a possible solution to the problem of time travel.

Thanks,

simul iustus et peccator
MNKBDKY

Tristan Scott

I think that any object in motion relative to an object that is stationary will move forward in time at a faster rate. It is just that unless you approach the very high velocities the difference is hard to measure. It's part of Einsteins special theory of relativity-"a clock in motion runs slow."

In the Hafele and Keating Experiment, conducted in 1971, they took atomic clocks around the world flying from west to east. They noted that there was a "time dilation" in that the airborne clocks elapsed slightly less time than the stationary clock in their lab.