Molinism is an attempt to provide a solution to the classic philosophical problems associated with God's providence, foreknowledge and the freedom of humanity. This view may be traced to the 16th century Jesuit theologian Luis de Molina - hence, the name Molinism. Specifically, it seeks to maintain a strong view of God's sovereignty over creation while at the same time preserving the belief that human beings have self-determined freedom, or libertarian free will.
"Molina's doctrine is called scientia media, or middle knowledge, because it stands in the middle of the two traditional categories of divine epistemology as handed down by Aquinas, natural and free knowledge. It shares characteristics of each and, in the logical order of the divine deliberative process regarding creation, it follows natural knowledge but precedes free knowledge."
"Luis de Molina’s solution to the freedom/foreknowledge dilemma has had a revival of sorts in the latter half of the twentieth century, most notably through the efforts of William Lane Craig, Alfred Freddoso, Jonathan Kvanvig, Thomas Flint, and Alvin Plantinga. In short, these thinkers have followed the Jesuit Counter-Reformer in postulating a middle knowledge between God’s natural and free knowledge." 
Variations of God's knowledge
"The most famous distinctive in Molinism is its affirmation that God has middle knowledge (scienta media). Molinism holds that God’s knowledge consists of three logical moments. These “moments” of knowledge are not to be thought of as chronological; rather they are to be understood as “logical.” In other words, one moment does not come before another moment in time, rather one moment is logically prior to the other moments. The Molinist differentiates between three different moments of knowledge which are respectively called natural knowledge, middle knowledge and free knowledge."
- Natural Knowledge – This is God’s knowledge of all necessary and all possible truths. In this “moment” God knows every possible combination of causes and effects. He also knows all the truths of logic and all moral truths.
- Middle Knowledge – This is God’s knowledge of what any free creature would do in any given circumstance, also known as counterfactual knowledge. It is also sometimes stated as God's knowledge of the truth of subjunctive conditionals.
- Free Knowledge – This is God’s knowledge of what He freely decided to create. God’s free knowledge is His knowledge of the actual world as it is.
God's knowledge and the decreed creation
The following is a synopsis of the logical order postulated in Molinism, relating the aspects (or moments) of God's knowledge to the world He chose to create.
- God's knowledge of all possible and necessary truths (natural knowledge -- of what could happen).
- God's knowledge of all feasible worlds (middle knowledge -- of what would happen through free choices under certain circumstances, including counterfactuals).
- Divine decree to create His selected world.
- God's Foreknowledge set through His selected decree (free knowledge -- of what will come to pass).
Postulating a middle knowledge and placing it between God's knowledge of necessary truths and God's creative decree is crucial to the Molinist scheme. By placing middle knowledge (and thus counterfactuals) before the creation decree, God conceivably allows for man's freedom in the libertarian sense. Placing this middle knowledge logically after necessary truths but before the creation decree also allows God to survey all feasible worlds and decide which world to actualize.
"Biblically speaking, Molinists are more in line with the Arminian view. God chooses who will be saved because He knows who would choose Him. However, Molinists are more philosophically sophisticated than the typical Arminian. For example, William Lane Craig avoids the criticism that God’s decisions are dependent on man’s decisions by holding that God’s middle knowledge is not derived from His knowledge of the world. Rather, God’s middle knowledge is based on His existing natural knowledge. In this way he hopes to uphold God’s perfect omniscience. So, today’s evangelical Molinists are basically philosophically sophisticated Arminians."
Proposed biblical evidence for Middle Knowledge
- Exodus 13:17
- 1 Samuel 23:8-14
- Jeremiah 23: 21-22
- Matthew 11:21-24
- 1 Corinthians 2:8
- Craig, William Lane. The Only Wise God: The Compatibility of Divine Foreknowledge and Human Freedom (Baker, 1987).
- Craig, William Lane. The Problem of Divine Foreknowledge and Future Contingents from Aristotle to Suarez (New York: Brill, 1988).
- Flint, Thomas P. Divine Providence: The Molinist Account (Ithaca: Cornell, 1998).
- Hasker, William. God, Time, and Knowledge (Ithaca: Cornell, 1989).
- Molina, Luis de. On Divine Foreknowledge: Part IV of the Concordia. Translated by Alfred J. Freddoso (Ithaca: Cornell, 1988).
- Plantinga, Alvin. The Nature of Necessity (Oxford: Clarendon, 1974).
- Laing, John D. "The Compatibility of Calvinism and Middle Knowledge," JETS 47:3 (Sep 2004).
- Hasker, William. "A New Anti-Molinist Argument," Religious Studies 35:3 (September 1999): 291-97.
- Compatibilist Middle Knowledge
- Best of all possible worlds
- Libertarian freedom
- Middle Knowledge at Internet Encyclopedia of Philosophy -- Recommended overview by John D. Laing
- What is Molinism and is it biblical? at Gotquestions.com
- Molinism at Basictheology.com
- Molinism by Alfred Freddoso
- A 'middle' knowledge perspective on the doctrine of Divine Providence by Thomas Rauchenstein
- Articles on Middle Knowledge (Molinism) at monergism.com
- Middle Knowledge and Christian Exclusivism by William Lane Craig
- Middle Knowledge, Truth–Makers, and the "Grounding Objection" by William Lane Craig
- The Heresy of Middle Knowledge by Dr. C. Matthew McMahon.