The three major theories of temporal reality are presentism (reality includes only the present), growing block (reality includes the present and past) and eternalism (reality includes past, present and future).
A recent option that has been considered is thick presentism on which reality includes a short segment of time including the present. This lets one have some of the intuitive advantages of presentism (dinosaurs and Martian settlements don’t exist) while at the same time neatly solving the problem of diachronic causation. Moreover, it raises an interesting explanatory problem: why does our world have the kind of temporal reality it does.
I think that if thick presentism is metaphysically possible, likely so are a number of other views:
Very thick presentism
Time-variable thickness thick presentism
Growing block
Space-variable thickness thick presentism
Swiss-cheese temporal reality.
On very thick presentism, the band of reality in thick presentism becomes extremely thick, say a million years. For there seems to be no compelling reason why the band of reality posited by thick presentists would have to be thin.
On the time-variable thick presentism, we have a thick presentism where the thickness varies with time. This is likely something that the thick presentist has to countenance. For, plausibly, some moment within the thick present has to be distinguished as “very present” to avoid violating the law of non-contradictions (since objects will have contradictory properties within the thick present). Suppose that that moment happens to be at the middle of the thick present. Then when the very present gets closer and closer to the beginning or end of time, the band of reality must get thinner and thinner. Or suppose the moment happens to be at the end of the thick present (I think that may be the better theory). Then when the very present gets closer to the beginning of time, the band of reality gets thinner and thinner. We also get time-variable thick presentism by applying patchwork principles to recombine worlds with thick presentisms of different thicknesses.
Growing-block with a finite past is just a time-variable thickness thick presentism where the very present is at the end of the thick present and the thickness of the thick present at t is equal to the duration from the beginning of time to t. And if we allow it with a finite past, why not with an infinite one—assuming an infinite past is possible?
Applying patchwork principles to thick presentisms with different thicknesses, we can get a space-variable thick presentism—here, the present may be ten minutes thick, but there it may be ten years thick.
Once we allow that, why not go all the way and allow a swiss-cheese temporal reality, where at any given time various chunks of the four-dimensional manifold are included or left out in a pretty arbitrary fashion (perhaps subject to some restrictions to make causation work)?
Now, here’s a fun theological speculation. Some thinkers are worried about eternalism and growing block on theological grounds: they worry that these theories imply that horrendously evil events like the Holocaust will eternally be a part of reality, and that this is inappropriate. But once we have expanded the range of options as we have, we can have some interesting theological theories.
For instance, perhaps, growing block is true between now and the Second Coming. Then at the Second Coming the band of reality gets very thin, so that after the Second Coming, the band of reality includes only the times from the Second Coming to the then-present. We can think of this as giving a surprising reading of the “Behond, I make all things new” of Revelation 21:5—the past events and object suddenly get wiped out of reality. Or, as a variant, perhaps partial eternalism becomes true after the Second Coming: reality now includes all times from the Second Coming on.
But one may worry that that wipes out too much—for instance, it wipes out the glory of the Cross (I am grateful to a graduate student for this worry). Very well. Then we go for a swiss cheese version where we have selective removal from reality—the Holocaust goes but the Cross stays, say.
All this has a certain resemblance to Hud Hudson’s hypertime story. But it’s different in two ways. First, it doesn’t need hypertime. Second, I am assuming here a variant of a standard presentist picture on which there are tensed truths, and the tensed truths function according to standard temporal logics. Thus, if it is true that p, it will always be true that it was true that p. What changes is what events and substances fall within the domain of restricted quantifiers—quantifiers do not commute with “at t” and other temporal operators.
For instance, on the “I make all things new” theories, right now all three of these are true:
There exists an x such that at 327 BC: x is a horse named “Bucephalus”
At 327 BC: there exists an x such that x is a horse named “Bucephalus”.
At 2000 AD: there exists an x such that at 327 BC: x is a horse named “Bucephalus”.
After the second coming, when the past objects and events are wiped out, we still have (b) and (c) holding, but (a) does not hold.
On a hypertime variant of “I make all things new”, once the past was wiped out, we would have none of (a)–(c).
I do not endorse any of these odd possibilities, because I am a die-hard B-theorist.
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