## Thursday, November 16, 2017

### Two moment presentism

The biggest problem for presentism is the problem of diachronic relations, especially causation. If E is earlier than F and E causes F, then at any given time, this instance of causation will have to either be a relation between two non-existent relata or a relation between one existent and one non-existent relatum, and this is problematic. Here’s a variant on presentism that solves that problem.

Suppose time is discrete, but instead of supposing that a single moment is always actual, suppose that always two successive moments are actual. Thus, if the moments are numbered 0, 1, 2, 3, …, first 0 and 1 are actual, then 1 and 2 are actual, then 2 and 3 are actual, and so on. We then say that the present contains both of the successive moments: the present is not a moment. It is never the case that a single moment is actual, except maybe at the beginning or end of the sequence (those are variants whose strengths and weaknesses need evaluation). Strictly speaking, then, we should label times with pairs of moments: time 1–2, time 2–3, etc. (There are now two variants: on one of them, time 2–3 consists of nothing but the two moments, or it also has an “in between”.)

We then introduce two primitive tense operators: “Just was” and “Is about to be”. Thus, if an object is yellow from times 0 through 2 and blue from time 3 onward, then at time 2–3 it just was yellow and is about to be blue. We can say that an object is F at time 2–3, where Fness is something stative rather than processive, provided that it just was F and is about to be F. We might want to say that it is changing from being F1 to being F2 if it just was F1 and is about to be F2 instead (or maybe there is something more to change than that).

We can now get cases of direct diachronic causation between events at neighboring moments, and because both of the moments are present, our “two-moment presentist” will say that when the two moments are both present, causation is a relation between two existent relata, one at the earlier moment and the other at the later. Of course, there will be cases of indirect diachronic causation to talk about, where some event at time 2 causes an event at time 4 by means of an event at time 3, but the two-moment presentist can break this up into two direct instances of diachronic causation, one of which did/does/will take take place at time 2–3 and the other of which did/does/will take place at time 3–4.

I bet this view is in the literature. It’s too neat a solution to the problem not to have been noticed.

#### 1 comment:

Martin Cooke said...

If it was me, I would do such a 2-moments Presentism in the language of mereology; but my problem with it is: how does a moment become real? Before it is real it does not exist, so there is nothing to get real! Similarly, what happens to present moments when they cease to exist? It is plausible that things that exist are always more than nothing.

And what about things that change at different rates? (Is this Zeno's stadium?)

(As a presentist, I think of the present moment as reality, which changes; if I wonder how that happens then I have to try to do so without introducing the classical temporal model of a line of moments. As yet, I have not got very far with that!)