One of the strongest objections to the doctrine of Molinism is what has commonly been called “the grounding objection” which, stated simply, is; “Where is God’s knowledge in future events grounded?”
Many who ask this question object the idea that, if God’s knowledge is based in his eternal decree then Molinism is undone because it eradicates the notion of libertarian freedom. On the other hand, they think that if the Molinist says that God’s knowledge is grounded in the decisions of his free creatures then God is somehow handcuffed by his creation.
They further find it strange that the leading Molinist apologists such as William Lane Craig and Alvin Plantinga are strangely silent (in their minds at least) about this objection.
I don’t think it is that Craig or Plantinga fail to take seriously the grounding objection so much as they simply find the objection to be incoherent given the presupposition that counterfactuals are true regardless of their instantiation. That is, they are true regardless of whether they obtain or not AND whether the actors in question exist or not. In short, the question of where God’s knowledge of future free decisions is incoherent at the outset because it presupposes that true statements require grounding in the first place. My question when such an objection is raised is when would we suppose that a tensed factual statement such as “I will be in the office tomorrow morning” becomes true?
In sum, the grounding objection begins with a flawed premise that presupposes that knowledge of future-free events must be contingent on the will of either God. The answer, however, is to expand our options to include the possibility that the knowledge of future-free events is what some philosophers call a “brute fact” that God knows in accordance with His omniscience so that the question of where God’s knowledge of future events is grounded is answered by His omniscient nature, not his eternal decree (or man’s finite and contingent decree).
For a better and more in-depth answer to the grounding objection I would point to Thomas P. Flint’s book, Divine Providence, chapter 5 which is also referenced in this article by Craig.