## Tuesday, October 24, 2023

### Does denying bivalence get us out of the logical argument for fatalism?

Consider this seemingly standard argument for logical fatalism.

1. It is true that you will ϕ or it is true that you will not ϕ.

2. If something true now is incompatible with it’s being true that p, then p is not within your power.

3. If you are free with respect to ϕing, then it is within your power that you will ϕ and it is within your power that you not ϕ.

4. That you will ϕ and that you will not ϕ are incompatible.

5. So, if it is true that you will ϕ, then it is not within your power that you will not ϕ. (2, 4)

6. So, if it is true that you will ϕ, then you are not free with respect to ϕing. (3, 5)

7. Also, if it is true that you will not ϕ, then it is not within your power that you will ϕ. (2, 4)

8. So, if it is true that you will not ϕ, then you are not free with respect to ϕing. (3, 7)

9. So, you are not free with respect to ϕing. (1, 8)

Many open futurists want to refute arguments for logical fatalism by supposing that in cases of freedom, that you will ϕ is indeterminate (and hence neither true nor false), and that you will not ϕ is also indeterminate, which allows them to deny premise 1 of the above argument.

But now consider this argument.

1. It is now indeterminate that you will ϕ.

2. Necessarily, p if and only if it is true that p.

3. So, it is true that it is now indeterminate that you will ϕ. (10, 11)

4. That it is indeterminate that you will ϕ and that it is true you will ϕ are incompatible.

5. That it is indeterminate that you will ϕ and that you will ϕ are incompatible. (11, 13)

6. If something true now is incompatible with it’s being true that p, then p is not within your power.

7. If you are free with respect to ϕing, then it is within your power that you will ϕ.

8. So, that you will ϕ is not within your power. (10, 14, 15)

9. So, you are not free with respect to ϕing.

Premise 15 of this argument is the same as premise 2 of the first argument. Premise 16 is an even less controversial version of premise 3. So anybody who is impressed by the first argument will be impressed by premises 15 and 16. Premise 13 is obviously true, and is an immediate consequence of the fact that a proposition that is indeterminate is neither true nor false.

Premise 11 is the plausible Tarski T-schema (necessitated, because we can think of the T-schema as an axiom). It has been questioned, but it is still very plausible.

Finally, premise 10 is a commitment of our open futurist.

So, unless our open futurist denies the T-schema, the supposition of indeterminacy leads to fatalism just as determinacy did!

Suppose we deny the T-schema. Nonetheless, even without the T-schema to back them up, 12 and 14 are still plausible as they stand, and so we still have a pretty plausible argument for fatalism, at least one that should be plausible by the open futurist’s lights.

I am not an open futurist. I just get out of the arguments by denying 2 and 15. Easy.

Tom said...

At the least, denying 2 and 15 seems inconsistent with accepting the consequence argument (and thus incompatibilism).

Alexander R Pruss said...

Tom:

We can accept Ockham's lesson that there is a difference between past-tensed propositions and propositions about the past.

Another way to put the point is that the consequence argument requires only that we think the conjunction of the laws with the physical descriptions of the world in the distant past is beyond our control. But the physical descriptions of the world in the distant past won't include propositions like "Alex will phi in 2023", which are needed for running logical fatalism arguments.

Atno said...

Seems like some confusion about what the presentist really thinks.
I have only glanced through this and haven't invested time into thinking what premise would be denied, but...
"That it is indeterminate that you will ϕ and that it is true you will ϕ are incompatible."
"If something true now is incompatible with it’s being true that p, then p is not within your power."
It seems like the argument is misrepresenting what the open futurist actually says (or wants to say). If it's indeterminate that you will phi, it's just that because at the moment when it's indeterminate you do not phi. The indeterminacy follows and describes the fact that you do not phi, but not because you can't phi, but just because it's not an actual fact. You *can* phi, because it is a potentiality. It's just that if you're not *actually* phi, then it's inseterminate - it's only potential.
I think the open futurist would want to adopt an Aristotelian act-potency analysis and that it can be helpful here.

Alexander R Pruss said...

"That it is indeterminate that you will ϕ and that it is true you will ϕ are incompatible" is hard to deny. After all "indeterminate = neither true nor false". Well, if it's neither true nor false that you will phi, then in particular it isn't true that you will phi!

After reflection, and correspondence with a friend, I think the open futurists' best bet is to deny (11), that the T-schema yields a necessary truths. This allows them to block the move from 13 to 14.