Free will means that each option has the possibility of being chosen. If the outcome is determined, then I do not have the freedom of making the choice myself.
If I will not choose anything else, how can you say I can?
Surely we can distinguish between “will” and “can”?
I “will” do x, presupposes as a matter of logic that I
can do x. The converse, however, is not true. Doing x, does not presuppose that I
cannot do y instead.
Here is a different example: suppose God exists, and is omniscient. He infallibly knows all facts about the past, present and future. From this it follows that God knows every choice I will make in my life, even before I was born.
Confronted with this idea, it is easy to suppose that no one has free will, that everyone MUST do, just as they do, because if they did something else, God would be wrong and God cannot be wrong.
The conclusion that we lack free will in the face of God’s omniscience is an example of the modal fallacy. Generally there are two kinds of fallacies, informal and formal. Formal fallacies are fallacies of logic, and cannot be hand-waved away. The modal fallacy is of this type, a logical fallacy.
Modal logic deals with modes of being, with necessity, contingency, possibility, actuality, etc. Under this heuristic, necessary truths are truths of logic — it is a necessary truth that triangles have three sides, for example.
When we look at the God example, we sense, correctly, that
something about this setup is logically necessary. The modal fallacy occurs when we misapply necessity.
We could say: If God knows everything I will do in advance, then I
necessarily do those things, because God cannot be wrong. If I
necessarily do what I do, then I have no free will, any more than a triangle can have four sides.
So now we have: If God knows in advance that I will do x, then I MUST (of logical necessity) do x. No free will.
Now it is certainly true that if God knows in advance I will do x, then I
will do x. God can’t be wrong.
The real question is, MUST I do x?
Let’s break the above proposition down into its component parts, its antecedent and its consequent:
ANTECEDENT:
If God knows in advance that I will do x …
CONSEQUENT:
… then I MUST (of logical necessity) do x.
But something is clearly amiss here. For me to do x is a
contingent truth — which means it could have been otherwise. It’s not at all like the logical truth that all triangles must have three sides. Therefore I CAN do y instead of x!
The problem with the above formulation of antecedent followed by consequent is that we have placed the formal necessity modal operator (a box symbol in formal modal logic)
in the wrong place. The fact that I do x is, was, and always will be,
a contingently true proposition, and never a
necessarily true proposition (the principle of the fixity of modal status, per Prof. Norman Swartz).
But surely, as noted earlier,
something in the formulation under discussion must be logically necessary. And it is, once we place the modal necessity operator in its proper place. Here is is:
Necessarily (if God knows in advance that I will do x, then I will [but not MUST!] do x)
In other words, the necessity operator must be applied CONJOINTLY to both the antecedent and the consequent, and not JUST to the consequent.
Once this is noticed, it becomes obvious that I have free will, and can freely choose either x or y. Suppose I choose y? Then we get:
Necessarily (if God knows in advance that I will do y, then I will [but not MUST!] do y)
I can do either x or y. What I
cannot do is escape God’s prior detection of my free choice.
I now invite you to apply this train of modal logic to the causal determinism/free will debate, and see what you get. Hint: whenever DBT informs Marvin that if Marvin orders salad instead of steak Marvin MUST order salad, he commits the modal fallacy (a fallacy of logic, recall). His misapplies the necessity box operator to the consequent of the antecedent rather than conjointly to the antecedent and consequent together. When this mistake is corrected, it becomes clear as a matter of logic that Marvin is free to order steak or salad and the whole argument to hard determinism simply evaporates. We then become eliminativist and note that hard determinism simply collapses into soft determinism (i.e., compatibilist free will).