MajGenl.Meade wrote:A recap. I do not believe that an actual infinity of moments can exist. Therefore, you and I agree that “not all possible things” have happened and that they in fact may not happen. They may remain “possible” until the end of time – after which they are no longer possible. OK so far?
At the moment, I see no reason to dispute that.
You surely agree that in the “set of infinite moments” any thing which does not occur in that set must be a thing that cannot occur? There is no other time outside the set of infinite moments in which this thing can occur. It must occur within the set or never occur at all.
I see a problem here: A hypothetically infinite set of moments[1] does not necessarily contain all moments. Consider the infinite set of all odd integers. That set does not contain any even integers. Nonetheless, it is infinite. Likewise, of course, the set of all even integers is also infinite, even though it does not contain any odd integers. Thus, there are integers not contained within each infinite set of integers: The even integers are not contained in the infinite set of all odd integers, and the odd integers are not contained in the infinite set of all even integers.
Now consider the hypothetically infinite set of all past moments. That set does not contain any future moments. (Nor does it contain the present moment, assuming that there is such a thing.) Nonetheless, it is hypothetically infinite. And whatever reasons there might be for concluding that such a set of past moments cannot actually be infinite, the fact it does not contain all moments (
i.e., it does not include any future moments) is surely not among them: If a set of integers can be infinite despite not containing all integers, is there any reason why a set of moments cannot be infinite despite not containing all moments? And the same goes for the hypothetically infinite set of all future moments: It does not contain any past moments, but it is still infinite.
The hypothetically infinite set of past moments does not contain all moments, just as the infinite set of all odd integers does not contain all integers. And the hypothetically infinite set of future moments does not contain all moments, just as the infinite of all even integers does not contain all integers. So does it not follow that a possible event which has not occurred in the hypothetically infinite set of past moments could still occur in the hypothetically infinite set of future moments? If not, why not?
MajGenl.Meade wrote:The paradox of infinite time (no beginning and no end) is that the number of moments prior to THIS moment is equal to the number of moments AFTER this moment. That is, an infinite number of moments has already happened. In fact, a set of infinite moments has already happened, which any future infinite moments you choose to posit cannot increase.
I do not see that it matters whether the infinite number of moments in the hypothetically infinite set of all past moments is or is not equal to the infinite number of moments in the hypothetically infinite set of all moments, past (and present?) and future.[2] (Or whether the infinite number of moments in the hypothetically infinite set of all future moments is or is not equal to the infinite number of moments in the hypothetically infinite set of all moments.)
If the infinite number of integers in the set of all odd integers is the same as the infinite number of integers in the set of all integers, there are integers (the even ones) which the set of all odd integers does not contain. And if the infinite number of integers in the set of all odd integers is not the same as the infinite number of integers in the set of all integers, there are still integers (the even ones) which the set of all odd integers does not contain. (And the same goes for the set of all even integers
vis-a-vis the set of all integers: Regardless of whether the infinite number of integers in the former is or is not the same as the infinite number of integers in the latter, there are integers (the odd ones) which the set of all even integers does not contain.)
And that, it seems to me, is what matters: The hypothetically infinite set of all past moments, despite its infinitude, does not contain all moments, because it does not contain any future moments. Therefore, a possible even which has not occurred in the infinite set of all past moments is not necessarily impossible, because it could still occur in one of the future moments which is not contained within the hypothetically infinite set of all past moments.
MajGenl.Meade wrote:Since we know that any possible thing which does not occur inside the set of infinite moments cannot happen and is therefore impossible, we must conclude that if the universe has “always existed” and therefore there is an infinite regress of time, all possible things have already happened including our extinction.
But as far as I can tell, we do not know that any possible thing which has not occurred within the hypothetically infinite set of past moments cannot happen within the hypothetically infinite (or, for that matter, even within a finite) set of future moments. Saying that (a) because a possible thing has not occurred within the hypothetically infinite set of all past moments, it cannot occur within the set of all moments, past (and present?) and future, seems to me like saying that (b) because even integers do not occur within the infinite set of all odd integers, they cannot occur within the set of all integers, odd and even.[3]
Or is there something about infinite sets of moments that is qualitatively different from infinite sets of integers? Is there some reason why a set of integers can be infinite without containing all integers, but a set of moments cannot be infinite without containing all moments?
MajGenl.Meade wrote:Since we are not extinct, this proves that an actual infinite regress of moments (time) is impossible, for not all possible things have happened yet. We agree on that.
I agree that not all possible things have happened yet. Again, however, I do not see how a possible thing's not having occurred in the hypothetically infinite set of all past moments precludes its occurring in the set of future moments which the hypothetically infinite set of all past moments does not contain. Even given an infinite set of all past moments, there are still moments out there (the future ones) in which the possible thing could occur.
MajGenl.Meade wrote:You deny that a non-believer must posit an infinite number of moments (always existing universe) but then you put forward the ping-pong universes in a cycle of expansion and contraction which had no beginning as if that’s an alternative. It isn’t. It relies upon the eternally existing (in the past) universe which means infinite regress.
Now – which is it? Did the universe have a beginning – a time when nothing was and then something was? Or has it always existed – in which case you do argue for an infinite regress just as I stated would have to be the case
I am not sure whether a non-believer must posit an infinite number of past moments. What interests me is your (and
thestoat's, but he declines to attempt to explain it in English[4]) assertion that an infinite number of past moments is not possible.
As I wrote before, I did not put forward the hypothesis of a cyclical universe as way of dealing with the general proposition that an infinite number of past moments is impossible. I put it forward as a way of dealing with the much more specific proposition that entropy makes the infinite (in time) existence of our universe is impossible. But it is not the only conceivable alternative to that specific proposition. Perhaps as the universe changes, the operation of entropy will change or cease. Perhaps the theory of entropy will, like so many theories before it, turn out to be wrong.
Did God have a beginning -- a time when God was not and then God was? Or has God always existed, in which case you are arguing for an infinite regress just as much as I am?
Or, if God can be uncaused, why cannot the universe be uncaused?
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1. I assume that we agree that what is at issue is the hypothetical infinitude of the number of moments contained in the set(s), not any infinitude of each moment.
2. I assume that this is what you are driving at. The proposition that the number of moments in the hypothetically infinite set of past moments is equal to the number of moments in the hypothetically infinite set of future moments seems to me, at least at this moment, unexceptionable: Neither of those sets contains any moments also contained in the other set.
3. If you are saying that an event which does not occur in either the hypothetically infinite set of past moments or the hypothetically infinite set of future moments (or in the present moment?) is an impossible event, then I see no reason to dispute that proposition. If it is true, the impossibility of the event depends on the exhaustion of the hypothetically infinite set of all future moments: As long as there are still future moments out there, the event remains possible. And because the set of all future moments is hypothetically infinite, there are always future moments out there. So the theoretical impossibility of the event never occurs. An event which remains possible forever is not, it seems to me, an impossible event.
4. In the case of approximations,
thestoat goes even further. Confronted with a discussion of the matter which states that although surely and almost surely are equivalent in questions of ordinary statistical probabilities but are importantly different in questions of infinitudes, he omits the qualification that they are equivalent only in questions of ordinary statistical probabilities, ignores the statement that they are importantly different in questions of infinitudes, and asserts that a finite number can be approximated to an infinite number. That sort of thing leaves me at a loss as to how to respond other than to point out his tactic.
Reason is valuable only when it performs against the wordless physical background of the universe.