Consider the following (non-deductive) line of reasoning in favor of an open future (cf. Rhoda, et al.):
- (a) Presentism is true, and hence (b) any facts that are true must be made true by present states of affairs. Moreover, (c) it is a cheat to allow such states of affairs as its being five minutes before George freely mows the lawn. (d) Without such cheats, the only way a fact about the future could be made true by a present state of affairs is if the present state of affairs causally necessitates the future fact. Since (e) not all future states of affairs are causally necessitated by present ones, (f) the future is open.
Now, consider the same line of reasoning with a past/present swap and a causal direction swap:
- (a) Presentism is true, and hence (b) any facts that are true must be made true by present states of affairs. Moreover, (c) it is a cheat to allow such states of affairs as its being five minutes after George freely mows the lawn. (d) Without such cheats, the only way a fact about the past could be made true by a present state of affairs is if the past fact is a necessary cause of the present state of affairs. Since (e) not all past states of affairs are necessary causes of present states of affairs, (f) the past is open.
Now I think 2a-d is precisely as compelling as 1a-d (in my view, neither is very compelling). There may be a difference, however, at step e in both cases. We have good reason to believe 1e, because of libertarian free will and quantum indeterminism. Do we have good reason to believe 2e? If we either believe in essentiality of origins or think that God is in time and his memories are caused by the state of affairs of which they are the memories, then we have some reason to deny 2e. Otherwise, it seems we would need to accept 2e–after all, apart from something like essentiality of origins and the issue of God’s memories, it seems like typically the effects produced by one cause, C1, could have been produced by another, C2. Thus, unless we believe in essentiality of origins or think that God is in time and has memories caused by the state of affairs of which they are the memories, if we accept 1a-f, we should likewise accept 2a-f. But 2f is absurd. Hence, we should likewise be very suspicious of argument 1 and its conclusion 1f.
Let’s now suppose that we reject 2e, either because of essentiality of origins or because of divine memories. I think 2a-d still leads us where we do not wish to go, and this fact shows a problem with 1a-d. Let’s take the divine memory case first (I think Alan Rhoda defends this in a recent piece). We got into this whole argument by worrying about truthmakers. On the divine memory proposal, what makes it true that Napoleon was vanquished at Waterloo is that God remembers Napoleon being vanquished at Waterloo. If T is the sole truthmaker of p, then a memory that p is solely about T. I will simplify by assuming God’s memories are the only truthmaker for Napoleon’s defeat. Thus, God’s memory of Napoleon’s being vanquished at Waterloo is solely about itself. But that is absurd. I doubt that there can be any memories about themselves, because memories are presently occurrent mental states which are about the past, and hence cannot be about themselves. And even if there can be memories that are about themselves, they would surely not have anything to do with making it true that Napoleon was vanquished at Waterloo. So the divine memory case gives us the wrong truthmakers.
Next, let’s take the essentiality of origins case. This requires us to deny the possibility of a past event that had no effects. Still, the truthmakers are far wrong. That dinosaurs roamed the earth is necessary for my existence given essentiality of origins, since the dinosaurs are in my causal history (e.g., by affecting the mating choices of mammalian “ancestors” of mine). Therefore, the belief that there were once dinosaurs on earth turns out to be, inter alia, about me. That is incredible.
The point that the above discussion should make clear is that it does not follow from
A past state S0’s causally had to occur for a given present state S1 to occur
A proposition reporting S0’s having occurred is made true by S1,
and hence the solution proposed in 2d fails.
But if so, then neither will it follow from:
A future state S2’s causally had to occur given present state S1
A proposition reporting that S2 will occur is made true by S1,
and the solution proposed in 1d fails.
If I am right, then a presentist needs to either (i) be an error theorist about all of the past and future, or (ii) deny the need for truthmakers, or (iii) allow “cheat” present states of affairs such as it’s being five minutes before George freely mows the lawn. If the presentist opts for (ii), she has no good argument for an open future. If she opts for (iii), I doubt she has one, either (unless one of the really bad logical fatalism arguments can be fixed up). If she thinks (i) is the best of the three options, then she ought to just deny presentism.