Friday, April 24, 2020

More on presentism and decisions

You have seven friends, isolated from each other for a week. And you have a choice between these three options:

  1. In four days, all of your friends will experience an innocent pleasure P at the same time.

  2. Over the next week, each day a different one of your friends will experience P.

  3. You presently experience an innocent pleasure whose magnitude is twice that of P.

It seems like a good idea to go for options 1 or 2 over option 3. But there is very little reason to prefer 1 over 2 or 2 over 1.

On eternalism, the parity between 1 and 2 makes perfect sense: in both cases, reality will contain seven copies of P, and the only difference is between how the copies are arranged in spacetime. And it also makes perfect sense that 1 or 2 is a better choice than 3: reality on 1 or 2 contains 3.5 times as much innocent pleasure.

But on presentism, I think it is difficult to explain these judgments. First, it’s difficult to explain why the sacrifice of 3 is worth it: a real, because present, pleasure is being sacrificed for a bunch of unreal, because future, pleasures. (Growing block has this problem, too.)

Now, if the choice is between 1 and 3, then at least the presentist can say this:

  • On option 1, there will be an occurrence of 3.5 times the pleasure that would have occurred on option 3.

I am dubious that it makes sense to compare the future pleasure to the present one on presentism, but let’s grant that for the sake of the argument.

But now suppose the choice is between 2 and 3. Then, one cannot say there will be 3.5 times the pleasure. Rather:

  • On option 2, on seven occasions, there will be half of the pleasure of option 3.

But the locution “on seven occasions” is misleading. For it makes it sound like there will be seven of something valuable. But there won’t be seven of something. Rather:

  • There will be one of P to friend 1, and there will be one of P to friend 2, and so on.

But one cannot conjoin these “will be” claims into a single:

  • There will be one of P to friend 1 and one of P to friend 2, and so on.

For that will never happen.

The deep point here is this. Cross-time counting on presentism is logically quite different from synchronic counting. In fact, in a sense it’s not “counting” at all, for there won’t be and has not been that number of items. One way to see the point is to compare the logical analysis of synchronic and cross-time counting claims on presentism:

  • “There are (presently) two unicorns”: There exist x and y such that x is a unicorn and y is a unicorn and x ≠ y and for all z if z is a unicorn, then z = x or z = y.

  • “There are (cross-time) two unicorns”: It was, is or will be the case that: There exists x such that x is a unicorn and it was, is or will be the case that there exists y such that y is a unicorn and x ≠ y, and it was, is and will be the case that for every z if z is unicorn, then z = x or z = y.

These are logically very different claims.

(I am also a little worried about the technical details of the cross-time identity claims on presentism, by the way.)


IanS said...

3. You presently experience an innocent pleasure …
This does not seem quite right. Wouldn’t you have to make your choice first, and only then (perhaps immediately afterwards) experience the pleasure? So while you are choosing, all the pleasures, including yours, are in the future, hence equally unreal to a presentist.

Alexander R Pruss said...

I was thinking about simultaneous causation, which seems logically possible.

IanS said...

I’m not seeing how that would work.

Your deliberations take time. Your pleasure is experienced over time. You can’t be experiencing the promised pleasure while you are deliberating – that would be cheating. At best, the promised episode of pleasure might begin precisely when you commit to your choice. Even granting this, episode will be almost entirely in the future.

Of course, I may well have missed a point.

Alexander R Pruss said...

That's true: I was thinking that the moment of decision can be simultaneous with the pleasure, but our deliberation precedes the moment of decision. It would have to be an instantaneous thinker.

In any case, the main point was just that trans-time counting is dubious and unnatural on presentism.