Here’s mine again: “There can be a possible world where this planet doesn’t exist [belief] because the possibility doesn’t depend on the material world from which we would not be able to derive that possibility [justification].”

My justification gives an explanation for how the possible world obtains on my terms, i.e. I reason that it’s being an abstract object which allows it to exist because on other terms it would not be able to.

It seems to me you can condense yours down to this: “There can be possible worlds because there are possible worlds.” — AJJ

Sure, so here's mine again:

"There can be a possible world where this planet doesn't exist [belief] because the possibility is a result of the world not being strongly(/causally) deterministic; if that weren't the case, there would be no non-actual possibilities [justification]."

My justification gives an explantion for how the possible world obtains on my terms, i.e. I reason that being a consequence of a metaphysics that's not strongly(/causally) deterministic allows it to exist because on other terms it would not be able to.

It seems to me you can condense yours down to this: “There can be possible worlds because there are possible worlds.”

So in short:

Mine: "Possible worlds exist on my terms by being a factor of the world not being strongly(/causally) deterministic; otherwise nonactual possible worlds can't exist."

Yours: "Possible worlds exist on my terms because they do."

If you still have a problem with this, I think you're going to need to state your general criteria for explanations in a way that we can better check what purported explanations are really explanations.

I said, in another context, that I refuse to do arguments that hinge on whether something is an explanation unless general criteria for explanations are given, and this is the perfect example why.

I got suckered into this one, because it didn't seem initially like it was going to be one of these stupid "That's not an explanation" arguments.

So let's look at general criteria for explanations in a way that we can check them without just saying, "That's not an explanation!" "That's not a justification!" etc. at whim.

In my post above, by the way, I'm simply showing that one can do the exact same nonsense from either side.

My justification gives an explantion for how the possible world obtains on my terms, i.e. I reason that being a consequence of a metaphysics that's not strongly(/causally) deterministic allows it to exist because on other terms it would not be able to. — Terrapin Station

You’re reasoning there is to the effect that possible worlds exist because possible worlds exist. I’m saying that’s not reasoning anything, rather it’s making an assertion that possible worlds exist and leaving it there.

It seems to me you can condense yours down to this: “There can be possible worlds because there are possible worlds.” — Terrapin Station

But you can’t because I’m saying something additional to that, i.e. I’m explaining how possible worlds exist (as abstract objects) and not simply asserting that they do without any enabling reason why they do/can.

So I reject your claim that you can make the same objection from your side.

So your reasoning it seems is circular: possible worlds are explained by there being possibility which is explained by there being possible worlds. I’m saying that’s inadequate reasoning and so not a justification and so not an explanation as per the definitions I’ve quoted.

I’m explaining how possible worlds exist (as abstract objects) and not simply asserting that they do without any enabling reason why they do/can. — AJJ

But that's what I did. The world could be strongly deterministic. It's not. That's how (non-actual) possible worlds exist.

But that's what I did. The world could be strongly deterministic. It's not. That's how (non-actual) possible worlds exist. — Terrapin Station

And I’m saying that amounts to a simple assertion that there are possibilities without saying anything additional about how precisely they obtain.

So what are you saying additional that's not the same as an assertion that there are possibilities?

I’m saying there are possibilities/possible worlds (ways things could have been) and that these are abstract objects (something additional about how they obtain).

I’m saying there are possibilities/possible worlds (ways things could have been) — AJJ

Which is not additional, obviously.

and that these are abstract objects (something additional about how they obtain). — AJJ

So when I say that possibilities are concrete facts, I'm not saying something additional about how they obtain?

Why would "They are abstract objects" be something additional, but "They are concrete facts" isn't something additional?

So when I say that possibilities are concrete facts, I'm not saying something additional about how they obtain? — Terrapin Station

You’ve not been saying that in answer to my question of how they obtain. You’ve been saying simply that they’re a consequence of the world not being strongly/causally deterministic, which as I’ve pointed out is circular.

So what seems to have happened is you said this:

Possibilities are real--they're the fact(s) that the world isn't strongly/causally deterministic. That doesn't hinge on thought, but it's not abstract, either. — Terrapin Station

Which is circular as well it seems, but it does say implicitly that possibilities are concrete (material) facts. So then I asked you this:

How on your terms do those possibilities obtain? — AJJ

And you started giving circular explanations for how possibilities obtain, when what I’ve wanted to know the whole time is how possible worlds such as one where this planet doesn’t exist can obtain as something concrete as opposed to something abstract.

So I made an error in my last post: What I’ve been saying that’s additional is not simply that possibilities are abstract objects, but that their being abstract objects is what allows possible worlds to exist since they can’t depend on the present world for that - it’s that last claim I’ve been trying to verify by asking you how on your terms possible worlds obtain (where the answers so far appear to be point-missing and circular).

since they can’t depend on the present world for that — AJJ

You wouldn't think that an explanation has to conclude that something can't depend on the present world, would you?

If the explanation concludes "being concrete objects is what allows possible worlds to exist, since they CAN depend on the present world for that," why wouldn't that be an explanation just like yours, simply with a different conclusion?

If the explanation concludes "being concrete objects is what allows possible worlds to exist, since they CAN depend on the present world for that," why wouldn't that be an explanation just like yours, simply with a different conclusion? — Terrapin Station

Your claim that possible worlds can depend materially on the present world would have to be backed up in a non-circular fashion. And your explanation there isn’t a parallel to mine, which includes the claim that possible worlds can’t exist materially (which is valid so long as you remain unable to explain how possible worlds obtain materially).

So put simply the reason I reject your explanation as an explanation is its circularity, which isn’t something I think mine exhibits.

You wouldn't think that an explanation has to conclude that something can't depend on the present world, would you? — Terrapin Station

And I actually think I’ve been unfair to myself, since my explanation doesn’t conclude with what you say. The reason my explanation doesn’t wind up being circular is that abstract objects can be said to obtain within the divine intellect, which (if abstract objects exist) must exist necessarily unless abstract objects can be said to exist otherwise. Not an explanation you agree with obviously, but it doesn’t to my understanding wind up being circular.

The reason my explanation doesn’t wind up being circular is that abstract objects can be said to obtain within the divine intellect, which (if abstract objects exist) must exist necessarily unless abstract objects can be said to exist otherwise. — AJJ

I can't even make sense out of it, really. If abstract objects exist aside from "the divine intellect," and that's what we're talking about re possibilities being abstract objects, is that circular?

If abstract objects exist aside from "the divine intellect," and that's what we're talking about re possibilities being abstract objects, is that circular? — Terrapin Station

You’ll have to clearer yourself, I don’t know exactly what you’re saying there.

You’ll have to clearer yourself, I don’t know exactly what you’re saying there. — AJJ

You're saying that on your view your explanation isn't circular. Is that only because you're positing abstract objects as something "within the divine intellect," or would it not be circular if we're positing abstract objects period (so even if not "within the divine intellect")?

It seems to me the circularity is avoided by the abstract objects existing necessarily within a Platonic third realm or the divine intellect. Obviously objections can be raised against both possibilities, but I don’t think circularity is one of them.

It seems to me the circularity is avoided by the abstract objects existing necessarily within a Platonic third realm or the divine intellect. — AJJ

Okay . . . but it's a mystery why you'd think that. You'd need to explain why that would make something noncircular versus alternatives.

If it’s a logical necessity that abstract objects obtain within the divine intellect then it isn’t circular. If possibilities conceived of as abstract objects remain possibilities in the absence of contingent minds, then they must exist within an absolutely necessary mind, one that can’t not exist. It seems to me that once you’ve reached a logical necessity you’re at the end of a straight line of reasoning.

Hmm, so if I were to think that my explanation is a logical necessity, then it wouldn't be circular.

Of course, then we're just disagreeing on whether different things are logical necessities. You'd say your explanation is; I'd say my explanation is.

By the way, on my view, possibilities/possible worlds aren't conceptions, though we have conceptions about them.

But that's what I did. The world could be strongly deterministic. It's not. That's how (non-actual) possible worlds exist. — Terrapin Station

So when I say that possibilities are concrete facts, I'm not saying something additional about how they obtain? — Terrapin Station

So possibilities are both "non-actual" and "concrete facts"? Can you explain how that could be a coherent assertion?

So possibilities are both "non-actual" and "concrete facts"? Can you explain how that could be a coherent assertion? — Janus

Sure, it's the concrete fact--a specific, material fact about a specific event, that it isn't causally deterministic.

I have no idea what that is supposed to mean. I cannot see how physicalism can be coherently separated from determinism. From a purely physicalist perspective, even if quantum events are not deterministic, they are generally thought to "average out" such that events on our scale are deterministic.

I cannot see how physicalism can be coherently separated from determinism. — Janus

I don't know why you'd be thinking that physicalists have to be determinists. Could you give some info on how you arrived at that conclusion?

I'm assuming that you accept that indeterminism at the micro (quantum) amounts to determinism at the macro scale, and the physicalist/ naturalist idea that the universe is "causally closed". If you do accept those propositions, how would you account for the idea that different possibilities are more than than merely logical?

So, you say that possibilities are non-actual and yet are concrete facts. How would you describe the concrete existence of a possibility, i.e. in what form would it be physically instantiated? The idea of such possibilities somehow physically existing, and yet being non-actual, seems completely incoherent to me, so I'm just asking for you to give an account that clarifies what you mean by claiming such a thing.

Of course, then we're just disagreeing on whether different things are logical necessities. You'd say your explanation is; I'd say my explanation is. — Terrapin Station

I’ve demonstrated mine is. Can you demonstrate your conclusion is a logical necessity (without arguing in a circle)?

I mean to sum up my (adopted) explanation of things:

1. There are possibilities
2. They can’t be grounded materially in the physical world
3. So they must be abstract objects
4. If they’re abstract objects they can’t exist in the physical world but must exist in a mind or collection of minds
5. To remain possibilities in the absence of contingent minds they must exist within an absolutely necessary mind

Yours it seems to me is this:

1. There are possibilities
2. They can be grounded materially in the physical world

So the reason yours is circular and mine isn’t is our justifications for 2 in each case. I justify my 2 by showing that you seemingly can’t describe the way possibilities are grounded in the physical world, or that you do so simply by arguing in a circle. You justify your 2 by repeating your 1 (while assuming nominalism and materialism).

Wait, we're not really getting to why you're thinking that physicalists would be determinists, though.

Are you thinking of physicalism as being or having some sort of dedication or subservience to the scientific discipline of physics? (And you're thinking of physics as deterministic, with the possible exception of quantum mechanics?)

So the reason yours is circular and mine isn’t is our justifications for 2 in each case. I justify my 2 by showing that you seemingly can’t describe the way possibilities are grounded in the physical world, or that you do so simply by arguing in a circle. — AJJ

Your 2 is that one can't describe the way that possibilities are grounded in the physical world, so if that's your justification for 2, that's circular.

It seems almost like you're reading that possibilities are something in the material/physical world into your (1) by the way. And then you're seeing the rest of your argument as explaining how this can be the case by positing them as something other than things in the material/physical world. It seems like you're thinking of it as a parallel to religious-oriented cosmogenesis arguments.

I’ve demonstrated mine is. — AJJ

I don't even think that your view is coherent.