Only if I claim that it is true in world y that there are no truths. There is no contradiction when I claim (within world y) that it is true in world x that there are no truths.

The fact that a proposition has no truth value in world x does not entail that it also has no truth value in all other possible worlds. Likewise, the fact that a proposition is true in world y does not entail that it is true in all other possible worlds. The whole point of positing possible worlds at all is that the truth values for the same proposition can be different in different worlds.

(1) You have no idea what a and b are. They're variables. I'm not asking you to plug anything into the variables. That's why they're presented as variables. — Terrapin Station

Then a = b is redundant

(2) I'm asking whether you think the argument, as presented, with variables, is a valid argument or not. Whether premises are false has nothing to do with whether it's a valid argument. — Terrapin Station

To be honest I can't tell, you are not using a notation convention, and I don't want to transcribe it.

No if you claim it is true about world world x that there are no truths that is a contradiction because it is the case about world x that there are no truths.

Then a = b is redundant — m-theory

Well, they're identical. So what goes for one goes for the other. Setting forth an identity certainly isn't an "illegal" move in logic.

To be honest I can't tell — m-theory

Aren't you able to assess validity for "informal" logic, syllogisms, syllogisms with variables, etc.?

Yes
That is why it is a redundant step.
If they are identical you can just one symbol and it will represent the same thing.

No if you claim it is true about world world x that there are no truths that is a contradiction because it is the case about world x that there are no truths. — m-theory

Here, you're conflating about world x and in(side of) world x.

We're in world y, of course. Any claims we make about world x are made from within world y. Those claims can be about world x. But you're getting confused about the difference between that and what's IN world x.

It is you two that want to use world x and world y.

I simplified the gist in a much earlier post.
We can simply examine the claim that if there are no minds there are no truths in this world.

But I suspect you want to keep world y around so you can keep doing this circular reasoning thing.

I simplified the gist in a much earlier post.
We can simply examine the claim that if there are no minds there are no truths in this world. — m-theory

Which, in other words, is possible world x Possible world x is different than actual world y.

And stop mentioning circularity if you don't know what it refers to.

It is true that at one point in this world there were no minds, so world x is just a reference to that point in time in this world.

No if you claim it is true about world world x that there are no truths that is a contradiction because it is the case about world x that there are no truths. — m-theory

I do not understand this sentence. Let P = "there are no truths in world x." What you seem to be saying is, "If you claim it is true that P, that is a contradiction because it is the case that P." This looks like exactly the opposite of a contradiction to me.

It is true that at one point in this world there were no minds, so world x is just a reference to that point in time in this world. — m-theory

And according to @Terrapin Station, at that point in time in this world, there were no truths. But he is asserting that now, when there are minds and truths. Obviously no one asserted it back then.

Sure, we could talk about Time T1 versus T2. I pointed out the confusions you were making with that earlier.

In that context, the problem wout be this:

"Here, you're conflating about T1 and at T1."

"We're at time T2, of course. Any claims we make about T1 are made at T2. Those claims can be about T1. But you're getting confused about the difference between that (claims made at T2 about T1) and what's at T1. "

Let say world x is a set.
You are saying there is set such that the set is empty and such that the set does not contain itself which we will call x.
You then proceed to say that set y contains the set x that is empty but that set x contains itself.
That is a contradiction..

Which

And according to Terrapin Station, at that point in time in this world, there were no truths. But he is asserting that now, when there are minds and truths. Obviously no one asserted it back then. — aletheist

Yes this is circular, truth depends on minds, because there are minds now therefor truth depends upon them..
.

Old ground

If only we couldn't make your confusions "old ground."

Or your stubbornness.

Let say world x is a set.
You are saying there is set such that the set is empty and such that the set does not contain itself which we will call x.
You then proceed to say that set y contains the set x that is empty but that set x contains itself.
That is a contradiction.. — m-theory

I'm not saying anything about sets containing themselves.

You are saying that world y contains world x.
Same difference.

You are saying that world y contains world x. — m-theory

What in the world? No. I'm not saying anything like that. Again, maybe try understanding what I'm saying rather than being so obsessed with "disproving" it. You're disproving things that are not at all what I'm saying, because you're not that interested in what I'm actually saying.

You are saying that world y contains world x. — m-theory

No one is saying this. You are now claiming that any propositions about world x can only be asserted in a world that contains world x. This is not how possible worlds work.

Maybe we should try formulating a straightforward counterfactual claim, rather than talking about possible worlds. This is what I understand @Terrapin Station to be advocating:

If there were no minds in our actual world, then there would be no truths in our actual world.

The only way that an if-then statement can be self-contradictory is if the antecedent is P and the consequent is not-P. That is not the case here, so there is no self-contradiction.

As far as I can tell there is no possible world argument such that it is necessarily true that truth depends upon minds and only minds.

I can't even make out a modal argument that this is the possible case.

The only way that an if-then statement can be self-contradictory is if the antecedent is P and the consequent is not-P. That is not the case here, so there is no self-contradiction. — aletheist

If there are no minds = P
Then there are no truths =Q (self refuting)

As far as I can tell there is no possible world argument such that it is necessarily true that truth depends upon minds and only minds. — m-theory

I'm not saying anything about it being necessarily true, though.

Given what I think truth is, after all, the whole idea of something being necessarily true is wonky.

It's fine for a game-like construction a la modal logic, though.

If there are no minds = P
Then there are no truths =Q (self refuting) — m-theory

???

As far as I can tell there is no possible world argument such that it is necessarily true that truth depends upon minds and only minds. — m-theory

NO ONE IS CLAIMING THIS!

Ok then it is not true that there are no truths. — m-theory

That is irrelevant. Do you agree that the following statement is NOT self-contradictory?

If there were no minds in our actual world, then there would be no truths in our actual world. — aletheist

Note that I am NOT asking you whether you agree that this statement is true; it can still be false even if it is not self-contradictory.

And I offered to concede the point that it may be true and that we can't know.

That is irrelevant. Do you agree that the following statement is NOT self-contradictory? — aletheist

What statement?

Knowing something doesn't have anything to do with certainty or with it being necessarily true.

Perhaps that is a different topic you could post.

Seriously? This statement:

If there were no minds in our actual world, then there would be no truths in our actual world.

NOT self-contradictory, right?