The term “Molinism” is making it into the headlines of the blogosphere a lot these days. So perhaps you want to know, in thirty seconds, how Molinism differs from Calvinism. The short answer is that Molinism views man’s will differently, and that consequently Molinism holds to “middle knowledge” to explain how God can have a comprehensive plan for all of human history.
Alfred J. Freddoso, Professor of Thomistic Studies at Notre Dame, explains Molina’s position this way (source):
According to Molina, then, the basis for God’s providence and for his foreknowledge of absolute future contingents is threefold:
(i) his pre-volitional natural knowledge of metaphysically necessary truths,
(ii) his pre-volitional middle knowledge of futuribilia, and
(iii) his post-volitional knowledge of the total causal contribution he himself wills to make to the created world.
By (i) he knows which spatio-temporal arrangements of secondary causes are possible and which contingent effects might possibly emanate from any such arrangement. By (ii) he knows which contingent effects would in fact emanate from any such arrangement. By (iii) he knows which secondary causes he wills to create and precisely how he wills to cooperate with them via his intrinsically neutral cooperating grace and general concurrence. So given God’s pre-volitional natural knowledge and middle knowledge, he is able to choose a comprehensive providential plan; and given further his post-volitional knowledge of what his own causal contribution to the created world will be, he has free knowledge of all absolute future contingents.
The Reformed position, as represented by the real Francis Turretin, differs from Molina’s position in that the Reformed deny the middle of those three alleged bases of God’s knowledge regarding the future. We acknowledge only Natural and Free knowledge, not “middle knowledge.”
The reason for having “middle knowledge” in the Molinistic scheme of things is a view that what a creature would do in any given situation is neither a matter of God’s choice nor a matter of absolute necessity. In other words, God cannot (according to the Molinist) decide what man would do in any given circumstance, he can simply decide whether or not to let the circumstance arise.
One might liken the Molinist conception of God to that of a person playing Scrabble(R). You get a tray of tiles from which to form words, and you arrange them the best you can. God makes the best of the tiles he’s dealt, in terms of what creaturely free will would do in every possible circumstance.
In Calvinism, God also decides what the tiles will be. So, one might reasonably conclude, in Calvinism God’s omnipotence is more expansive than in Molinism, because it extends also to the free choices of free creatures. It seems as though the Molinist’s only answer is to assert that if God determines what the creature’s choices will be, then those choices aren’t really free.
As Freddoso explains (in the same paper):
Molina argues strenuously that this Bañezian doctrine is incompatible with human freedom and falls into the strict determinism advocated by the Lutherans and Calvinists. For even though the Bañezians, like Molina, insist that a free act of will cannot result by natural necessity from antecedently acting causes, they nonetheless assert that an act of will can be free even if God has predetermined to cooperate with it contemporaneously by a concurrence or grace that is intrinsically efficacious (or inefficacious). This Molina denies: ‘That agent is called free who, with all the prerequisites for acting having been posited, is able to act and able not to act, or is able to do one thing in such a way that he is also able to do some contrary thing.’ And numbered among these prerequisites is God’s fixed intention to confer his general concurrence and grace. So if God has decided to confer only intrinsically efficacious (or intrinsically inefficacious) grace or concurrence in a given situation, the created agent’s freedom is destroyed.
As you can see, ultimately it comes down to a question of whether a will – in order to be free – must have an ability that it never, ever uses – the ability to do the contrary. This rationale seems to be what drives the engine of Molinism, and while many people accept this rationale, you’ll never find it in Scripture.