Or “On the Non-Existence of Actual Alternate Possibilities”.

On my view there are three major categories of possibility: logical, metaphysical, and actual. Logical possibilities are those permitted by logic, metaphysical possibilities are those permitted by logic and [the laws of metaphysics, of which the best way we have come up with to discern is through conceivability experiments], and actual possibilities are those permitted by logic, [the laws of metaphysics], and actuality.

There are alternate logical possibilities all over the place. For example, there is no logical reason why there couldn’t be an object which is opaquely red all over and opaquely green all over in the same way at the same time. While such an object is inconceivable and so it is not metaphysically possible, there is nothing logically contradictory about it and so it is logically possible. But in addition to logical possibilities that are not metaphysically possible, all metaphysical possibilities are also logical possibilities.

There are also manifold alternate metaphysical possibilities. For example, there is no metaphysical reason why there couldn’t have been a larger or smaller quantity of matter in the universe. While the actual universe has exactly as much matter in it as it does and so there is no actual possibility that the universe has a larger or smaller quantity of matter, there is nothing inconceivable about it and so it is metaphysically possible. But in addition to metaphysical possibilities that are not actually possible, all actual possibilities are also metaphysical possibilities.

However, there are not any alternate actual possibilities. This is not to deny that there are *any* actual possibilities, but only that there are any *alternate* actual possibilities. This can best be understood by examining actual possibilities in three phases.

Firstly, there are actual possibilities concerning the past. Obviously it was actually possible for Barack Obama to get elected, because he did. But because he got elected, there is no longer any chance that in the actual world, Obama does not get elected. And this is true for all propositions concerning the past: there are no *alternate* actual possibilities.

Secondly, there are actual possibilities concerning the present. Obviously it is actually possible for it to be gloomy in Coeur d’Alene, because it is. But because it is currently gloomy, there is no chance it can actually be sunny. Therefore, there are not any actual alternate possibilities concerning the present.

Finally, there are actual possibilities concerning the future. Obviously what ever ends up happening in the future, such will have been actually possible. But because the future will unfold one way as a matter of fact and not another, there are not any actual alternate possibilities. Another way of putting this is that future contingents, those propositions concerning the future which are not true out of metaphysically necessity, each have a truth value. It is *currently* either true or false that Jesus will actually return at sometime in the future. And the fact that such is currently either true or false means that whichever one is the case is true of the actual world. And if it is true of the actual world, then no actual alternate possibility exists. The fact that it is conceivable that Jesus not return makes such scenario a metaphysical possibility, but not [necessarily] an actual one.

DerekGood stuff, Louis.

If I’m reading you right, it seems no actual possibility has its alternative compliment. I.e. if p is actually possible, then ~p is not actually possible (for simplicity’s sake, just assume p is time indexed to the past, though you seem to make all true time indexed propositions, including future ones, actual possibilities, which seems to rule out genuine alternatives for the future).

Thus, if p is actually possible, then ~p is actually impossible. But despite ~p being actually impossible, could it still be metaphysically possible that ~p be actually possible?

So let’s p say ‘I went to idaho’ and let p be true. On your view, p is actually possible, and it seems that ~p, which says ‘I want to idaho’ is false, is actually impossible. My question: is it metaphysically possible that ~p is actually possible?

Think about it.

DerekSo let p say ‘I went to idaho’ and let p be true.***

LouisYou’re reading me correctly. Actual possibilities have no complements. All actual possibilities are actual necessities.

“is it metaphysically possible that ~p is actually possible?”

No, because p concerns the actual world, and is true. So ~p is metaphysically possible, but not actually possible.

Derek“So ~p is metaphysically possible, but not actually possible.”

And hence, it’s not metaphysically possible that ‘~p is actually possible’.

Suppose that p is both L and M possible, but that p is neither L nor M necessary. Such a p might be “Derek is Louis’ friend”. Suppose that p is true, and hence, p is actually possible. You agree that if p is actually possible, it is both L and M possible. Since p is M possible, and neither L nor M necessary, it seems that ~p and p are both L and M possible. But in order for ~p to be L and M possible, it must (it seems) be the case that it could have been the case that ~p is actually possible. Suppose the following subjunctive conditional is true:

© Had David not known Derek, then Derek would have never know Louis.

The truth of © entails ~p, since you cannot be friends with someone you don’t know.

Suppose that © is actually true. It follows that © is actually possible. And if © is actually possible, it seems that its consequence, ~p, is possible. For the following is an axiom of modal logic:

(AS) {[Vp & (p–>q)] –> Vq}

Where V = “it is possible that”

(AS) reads: If “it is possible that p, and it is true that ‘p entails q’,” then ‘it is possible that q’.”

Applied to our original case,

(1) if © is actually possible, then so is any of its consequences, which includes our original ~p.

(2) © is actually possible.

(3) ~p is actually possible.

Therefore, it is actually possible that “Derek is Louis’ friend” is false.

DerekI suppose you could get out of this by saying that though whole conditional, ©, is true, it’s antecedent, ‘David does not know Derek’, is false, and therefore actually impossible, and therefore its consequent, ‘Derek does not know Louis” is false, and thereby actually impossible, and hence, ©‘s consequent, that ~p, is not thereby actually possible.

Fine.

DerekGood. Thanks for helping me through this. As long as we (oddly) have the power to make it the case that p is actually possible (and thereby actually necessary) , where p describes what we have done or will do with our (libertarian) freedom, I’m okay with everything so far.

Louis“And hence, it’s not metaphysically possible that ‘~p is actually possible’.”

That’s right, as p is world-indexed to the actual world, and p is true.

Let’s rename your new “p” to “p”” for the sake of distinguishing it from our previous p or p’s.

“Suppose that [p”] is both L and M possible, but that [p”] is neither L nor M necessary. [Let p”] …be “Derek is Louis’ friend”. Suppose that [p”] is true, and hence, [p”] is actually possible. You agree that if [p”] is actually possible, it is both L and M possible. Since [p”] is M possible, and neither L nor M necessary, it seems that ~p and p are both L and M possible. ”

That’s all correct.

“But in order for ~p to be L and M possible, it must (it seems) be the case that it could have been the case that ~p is actually possible.”

Here’s where we diverge. On my view, all actualities (actual possibilities and actual necessities, which on my view happen to be the same

de facto) are true in the actual world, and ipso facto, all propositions which are not true in the actual world are therefore not actualities.In other words, if a proposition does not describe the actual world, it is not actual. Thus, metaphysical possibilities that do not obtain in alpha are not actual possibilities.

Therefore p”, since it does not describe the actual world, is not an actual possibility. So, p” could have been the case. This is what metaphysical possibility is designed to express. But p” could not have

actuallybeen the case.I admit that this is a non-intuitive use of the English word “actual”, but such is the price we pay for using vulgar terms in technical senses.

“I suppose… though [the] whole conditional, ©, is true, it’s antecedent, ‘David does not know Derek’, is false, and therefore actually impossible, and therefore its consequent, ‘Derek does not know Louis’, is false, and thereby actually impossible, and hence, ©‘s consequent, that ~p, is not thereby actually possible.”

That’s correct.

Jonathan Charles WrightResponse to main post:

So, there’s the stuff that happened/happens/will happen, and the stuff that could have happened, or could be happening, or could happen in the future. The stuff that happens in time constitutes the actual world. The coulda-stuff is the stuff of possible worlds. The former actuality; the latter possibility. I think I get all that.

But am I to read “actual alternate possibilities” as ‘stuff that could happen past/present/future, given stuff that happens past/present/future’? Your idea is to fix the course of history completely, and then to ask what possibly could happen given this complete history.

If this is what you intend, then it seems fishy. I wonder about what “possibility” as a basic notion even comes to when what has, is, and will happen is ‘fixed’ in this way. It seems that whenever we ask whether something is possible, just in regular speech, we are asking what at some later time could occur given what has happened before, keeping in mind relevant logical/metaphysical/physical laws.

Even when we talk about stuff that ‘could have happened’ in the past, like in the Obama case, we imaginatively retrospect to some time before the event in question and then say, given what had happened up to that point and given the rules of the universe we want to take into account, what could happen next? But when you provide a full description of what is the case in the entire world at time T, we don’t ask what could possibly happen at time T, since that’s provided. Even the actual world’s history is called a ‘possible’ way things could play out by virtue of its standing amongst a host of other ways things could have gone.

So, your ‘actual alternate possibility’ doesn’t seem like possibility, or at least not like any interesting kind. Surely not the kind of possibility we intuitively mean when we say that A “could have done otherwise”.

Do I misunderstand you? Am I clear? I feel like that was rambly.

Jonathan Charles WrightResponse to comments:

My only thought in reading the comments was that the way you use “actual possibility” is how I would use “actuality”. I don’t see how it’s a kind of possibility at all. You might reply, ‘but the actual world is one possible way things are’, and I’ll say sure, but whatever sense of possibility you invoke in saying so of the actual world is some independent sense of possibility by which we evaluate the actual world and possible worlds alike: other worlds are that kind of possible too. So when you say, ‘okay, but now that i have you admitting that the actual world is a possible world, i want to talk about the specific kind of possibility that only the actual world boasts’ you fail to pick out some specific kind of possibility. There is not unique kind of possibility that the actual world picks out: the actual world is indistinct from a multitude of non-actual worlds, in terms of their mere possibility. The thing that makes the actual world unique is its actuality, not its manifesting some special ‘possibility’.

I hope this is clear. I only harp on it because I think you mean to make the language of ‘possibility’ do some work for you as things progress, and I think it will have been by a kind of trick. Again, I hope I’m clear.

Louis“Your idea is to fix the course of history completely, and then to ask what possibly could happen given this complete history.”

Yes, I believe history is fixed. However, consider the following.

“…’actual alternate possibility’ doesn’t seem like possibility, or at least not like any interesting kind. Surely not the kind of possibility we intuitively mean when we say that A “could have done otherwise”.”

By that insight we can see that history is not fixed in any interesting sense. There will be a lot more on this in a future post.

As for your remarks about my use of “actual possibility”, I want to say I agree that the language is unconventional and therefore misleading. I thought about what else I could call the “actual” in “actual possibility”, but nothing acceptable came to mind. I will consider “factual”, but think I will run into similar semantic problems as I am with “actual”.

As for the “possibility” word choice in “actual possibility”, I concede that it too is unconventional and therefore misleading. But this time it is much more intentional, for it will become relevant in future posts.

Louis“though you seem to make all true time indexed propositions, including future ones, actual possibilities, which seems to rule out genuine alternatives for the future”

Just to be extra clear, I rule out ‘actual’ alternatives, not ‘genuine’ alternatives.

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