Bill Thompson 75
Graduate Poster
- Joined
- Apr 29, 2010
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You use the idea of logical impossibility inconsistently in your argument.For free will to exist, there must be a choice I can make, where it is possible that I choose either one. Pick a necessary binary choice "A or not A" (e.g. "I will stand up") and examine it. For me to have free will in this choice, it must be possible for me to choose A, and it must be possible for me to choose not A.
Let us assign the choice to time T2. (So, A might be, "I will stand up at noon.") At an earlier time T1, I have not yet made the choice. Let us also define a time T0, which is earlier than T1.
We can now be more precise about the free will condition: For me to have free will in the choice at T2, it must be possible at T1 for me to choose A at T2, and it must be possible at T1 for me to choose not A at T2.
At all times T0, T1, and T2 the Omniscient Being must know whether I will choose (or have chosen) A or not A.
Now, what does it mean for it to be "possible" for me to choose a choice? There are many elements involved in assuring that a choice is possible -- for instance, it's not possible for me to choose to have lunch in Honolulu today, because it is already lunchtime and Honolulu is thousands of miles away. But that's circumstantial impossibility. Under different circumstances (lunch tomorrow, or I happen to be an astronaut on the launch pad just about to blast off for a suborbital flight intended to splash down a few minutes later near Honolulu), it would be possible.
Of more import is when a choice would cause a logical contradiction. That makes it logically impossible. For example, I cannot choose to draw a square triangle even if I'm poised with pencil and paper, because a square triangle is a contradiction, as it has three sides (being a triangle) and other than three sides (being square) simultaneously. Likewise, if there is an omniscient being, it is not possible for me to utter a fact that the omniscient being doesn't know, as the omniscient being would have to both know and not know that fact. That would be a contradiction.
Logical impossibility is therefore sufficient to prove impossibility. Just because something is logically possible (e.g. lunch in Honolulu) doesn't mean it's actually possible, but if it not logically possible, then it is definitely not possible.
The omniscient being at time T1 knows that I will choose A or that I will choose not A.
Note that it is not possible for me to do other than choose A or not A (which would be, not A and not not A, that is, A and not A) because that itself would be a logical contradiction. At T2 I can either stand up, or not stand up; I cannot do both, or neither.
So, there are two possible cases at time T1:
- The OB knows I will choose A at time T2
- The OB knows I will choose not-A at time T2
In the first case, it is not possible at time T1 for me to choose not A at time T2, because that would be a contradiction. (By the definition of omniscience, the OB's knowledge at time T1 is sufficient to prove A at T2; by the definition of choice, my choice of not A proves not A at T2, so we have A and not A, a contradiction.)
In the second case, it is not possible for me at time T1 to choose A, because that would also be a contradiction.
Since one and only one of these cases must apply at T1, in no case is it possible for me at T1 to choose A at T2 and possible for me at T1 to choose not A at T2. So, one of the the original premises must be false. Either I cannot have free will to make a choice of A or not A at T2, or an omniscient being cannot know at T1 what my choice will be (and hence, cannot exist as defined).
What Bill is trying to argue using atemporal causality is something like this:
There are two cases, A (I choose A) or not A (I choose not A).
Both cases are possible at T0 and T1 (hence, free choice is preserved) but if I choose A at T2, the OB knows A at T0 and T1, and if I choose not A at T2, the OB knows not A at T0 and T1 (so omniscience is preserved).
But the fact remains, per the argument above, that at T1, the OB must know A or not A, so at T1 one of the choices must be impossible. The same applies to T0 and right up until T2 when the choice is made. So that argument amounts to, I have free will, I just don't have it at any given time. I have it never.
Respectfully,
Myriad
Your argument confuses two ideas.
1) The logical impossibility of a choice other than the one that is made
2) The logical impossibility of multiple options before choice is made
Your argument primarily addresses 1).
It appears to use 2) but that is because at any time T the choice made is already known.
Your argument is implicitly based on the premise that knowledge is the basis for the choice.
But if you do an analysis that uses the choice as the basis of the knowledge you will see that your argument is no longer valid.
An argument can be established using the following logic:
At any time T I cannot choose other than what the chooser knows.
At any time T the OB cannot have knowledge of the choice I make other than what I chose.
The truth of both of these statements is not a logical impossibility and they allow for a compatibility between omniscience and free will.