A frequent criticism of Molinism among laypeople is that it equates to causal determinism. “God chose to actualize the circumstances in which you do X, so that you could not have done any differently than you did. This means middle knowledge equals determinism.” My contention is that there are several misunderstandings within this type of critique.
First, and perhaps most fundamentally, middle knowledge cannot possibly entail determinism, by its very definition. This is because the knowledge is in between two other knowledge-moments. God’s free knowledge is everything known to God because he decreed it, including the actual world and its contents. God’s natural knowledge is his knowledge of all necessities and possibilities, including things that never come to pass. Middle knowledge, however, is distinct from free knowledge, because its content does not depend on the will of God (God’s will is logically posterior to the contents of middle knowledge); further, it is distinct from natural knowledge, because its contents are not necessary. Thus, by definition, middle knowledge counterfactuals are not deterministic.
However, let us suppose that the objector really means something like, “There cannot be any such thing as middle knowledge, since God’s actualization of a world means an agent cannot act any differently than he does act.” This is also problematic. What has happened is that the objector has failed to tease out precise meanings for these terms. What happens in God’s decree (on Molinism)? God decrees that the world be actual. This decree is based on a) necessary truths (which must be a part of any world God creates, by definition), b) truths of how God will act (which are entirely and completely up to God, encompassing the physical truths of nature and any actions of God with and for his creatures), and c) counterfactuals of creaturely freedom (which are, again by definition, not up to God [though whether or not God created a world with free creatures is, of course, entirely up to God—free will is God’s gift]). Since the truth or falsehood of the counterfactual is so logically prior to God’s actualization of a world, God’s decree is only that the counterfactual be actual (rather than merely abstract).
What is impossible, therefore, is not that the subject acts any differently. What is impossible is the composite state of affairs of “In C, X would freely do S at T; C &T are actual; X would not freely do S [or X would freely not-S].” It is the all-too-common modal fallacy to distribute the necessity over the entire composite to its individual conjuncts. Middle knowledge, and Molinism, are very difficult concepts. I am hoping that by this article some confusion may be avoided.
 Although the contents of middle knowledge appear in natural knowledge, they are only necessarily possible, not necessary in themselves.