In his discussion of the ideas of God, Ockham comments that “God has an infinite number of ideas, as there are infinitely many things which can be produced by him.” Although it’s tangential to the point Ockham is making, the quote puts me in mind that the whole shift in thinking about the nature of possibility which occurs between Thomas Aquinas and William of Ockham could be reduced to this. It is a shift from the possible understood as a theologically rich and analogical divine imitability, to a theologically evacuated and banal divine producibility.
Damian’s Theology of the Possible, part 3
According to the conventional reading of St. Peter Damian’s On Divine Omnipotence, God’s power over the realms of nature and grace are so great that not only can he restore a woman to her virginity in body and soul, but even the established past is liable to alteration by his omnipotent will. The key passage for this interpretation comes in the latter part of Damian’s letter:
I can say without appearing foolhardy, that God, in that immutable and ever uniform eternity of his, is able to bring it about that what had happened relative to our passing time, did not happen. For example, we may say: God can so cause it to happen that Rome, which was founded in antiquity, had not been founded. In saying, can, that is, in the present tense, we use the word properly insofar as it relates to the unalterable eternity of almighty God…
As this passage plainly indicates, because God is eternal his omnipotence cannot be conditioned and hence changed or diminished according to the passing of created time. Much as Boethius had defended the compatibility of divine foreknowledge and human free will by appealing to God’s eternality (the future is not future for God but present), so Damian asserts that neither is the past really past for God, but is still present for him. The inference drawn from this is that, for God in his free eternity, a past event is no less contingent than it was prior to its taking place. For an atemporal God, once a contingent event, always a contingent event. If God formerly had the ability of bringing it about that a particular event would not take place, then God always has that possibility. As Damian further explains, however, were God to decree something different to have occurred in the past than what has actually taken place, this would involve a change in the past only relative to us temporal creatures, and not for God in his atemporality. Insofar as God’s undoing of the past would further require that the same event both happen and not happen, many scholars have understood Damian to deny that even the law of non-contradiction represents a limit to the exercise of God’s power.
 Damian, On Divine Omnipotence, trans. O.J. Blum, 381.