I have been preparing for a phil religion class I will be teaching in the Fall and so have been thinking about a lot of these issues. Today I was reading Platinga’s defence of Human free will with God’s foreknowledge of what we will do. He formulates his defense in terms of a scopal difference so, (1) is true but 2 is false (where K(x)=God knows that I will do X in advance and D(x)=I actually do x)
1.  (K(x) –> D(x))
2. K(x) –> D(x)
2 is false according to him because there is a possible world (not the actual world) where I do not do X even though God knows that I will do X in the actual world. One thing that worries me is that (1) is equivelent to (1′)
(1′) K(x) –> D(x)
and (1′) does seem to entail that I am not free…
He then considers Pike’s modification of this argument which claims that it is an essential trait of God that he is omnicient. Pike’s version of teh arguement is that if God knows at T1 that I will do X at T2 then, if I do not do X at T2 I make the belief that God has a T1 false and this means that God is not omniscient. Plantinga’s response is to point out that to say that I could have done otherwise is to say that there is a world W where I do do otherwise but that this does not mean that God holds a false belief in the actual world.
The problem with this line of argument is that it assumes a view of possible worlds (i.e. Plantinga’s view!) that I find objectionable. To say that I could have done otheriwse is NOT to say that there is a possible world where I do do otherwise and that that world might have been actual! It is to say that I, in this world, might have done otherwise. Adapting Kripke’s humphry objection we can say that it is cold comfort to be told that my being free means that there is someone else who could have done something different than I did. That is nonsense! What it means to be free is that I, myself, could have done otherwise. So if I could have done otherwise in the actual world then God cannot know at T1 what I would do at T2 or if He does then I am not free. So I just don’t see why Plantinga’s response is anything more than question beging…unless I am missing something?