Thursday, November 14, 2019

Alternate timelines

The following sound right:

  1. It is always the case that s if and only if s at all times.

  2. It is always the case that s if and only if it is, always was and always will be the case that s.

But suppose, as may very well be the case, that we inhabit a multiverse whose universes all have temporally unrelated time sequences. Then (1) and (2) are apt to disagree. For (2) tells us that it is always the case that s just in case s at all past, present and future times. But in our multiverse scenario, there are times that are not past, present or future (from our point of view—which is surely the point of view we are speaking from). Thus, there is apt to be a difference between what happens at all times and what was, is and will be. For what happens at all times includes stuff that happens in other universes, since there are times that are found in other universes than ours. But what happens in the past, present or future only includes only what happens in our universe.

So, should we take (1) or (2) as the correct reading of “always”? I don’t know. (Note: I am assuming that the quantification over times in (1) is unrestricted, and hence not limited to times in our universe.) It’s a bit puzzling.

Moreover, one would have to say that right now, only a time in our time sequence is present. For if two times are present, they are simultaneous, but there are no simultaneity relations between our times and times in other time sequences. In fact, the times in the other time sequences never were and never will be present, since if they were or will be present, then they would not be temporally unrelated to times in our sequence. It sure sounds odd to talk of times that were not present, are not present and will never be present. But the ontology, nonetheless, seems to make perfect sense.

Or at least it makes perfect sense to me, a B-theorist. Could it make sense to a presentist? I am not sure. The presentist needs to make a distinction between “real” events like World War II and the 2020 Olympics, on the one hand, and merely possible events like the arrival of the Vulcans on Earth in 2053. None of these events are present, but obviously World War II and the 2020 Olympics are in some way real, while the arrival of the Vulcans is a mere fiction. The standard way for presentists to distinguish the arrival of the Vulcans from World War II and the 2020 Olympics is to say that World War II occurred and the 2020 Olympics will occur, while the arrival of the Vulcans neither occurred, nor is occurring nor will occur.

But if there are other time sequences, then the events on these time sequences are more like World War II and the 2020 Olympics than they are like first contact with the Vulcans. I do not see, however, how a presentist can possibly express the kind of reality the other time sequences in our (hypothetical) multiverse have.

(Here is a practical good from being able to make the distinction: It is right and proper to pray for all the beings in all the universes. But we shouldn’t pray for Vulcans and other fictional entities.)

In fact, I think the problem comes up even earlier, before considering any events. I don’t think the presentist can make any sense of the hypothesis of universes temporally unrelated to ours.

Thus we have an argument against presentism:

  1. It is possible to have each of two temporally unrelated time sequences.

  2. If presentism is true, it is not possible to have each of two temporally unrelated time sequences.

  3. So, presentism is not true.


Majesty of Reason said...

Couldn't the presentist simply say that the only things which exist simpliciter are those that are within a timeline and present at that timeline? In other words, "presently existing things" only exhaust reality *within a timeline*, and reality as such includes all the timeline-indexed present things. From the perspective of reality as such, there is no universal timeline; but still the spirit of presentism is preserved within each timeline.

Michael Gonzalez said...

I think #3 is not even false; it is meaningless. At least, if "temporally unrelated" means there is no fact of the matter about whether an even in Universe X happened before or after an event in Universe Y. There is a fact of the matter. All we need to do is ask the question from God's standpoint (or from the standpoint of the multiverse itself, if we say, for example, that the multiverse is bubbling up with Universes and expanding... such a process has an overarching timeframe to it within which there could be simultaneity or temporal order between events in distinct sub-universes).

Philip Rand said...

Michael Gonzalez

Alice and Roberta are two girls born in London, England at exactly the same time.

For 21 years Alice and Roberta live and remain only in London, England.

When they are both 22 years old, Roberta moves to Denver, USA while Alice remains in London.

The question is this:

After a year has passed since Roberta's emmigration, which girl is the oldest?

Martin Cooke said...

Your final argument, Alex, is a perfectly logical argument, and so it presupposes its conclusion. I therefore wonder if you are right to call it an argument against presentism.

As its second premise states, the first premise is false under presentism. A presentist who found that first premise plausible would have to choose between her presentism and that plausibility, but that is not in itself an argument against presentism.