 Some philosophers, notably Luis de Molina (1535–1600) and Alvin Plantinga, have held that God knows not only what actual people will freely do in the future, but what each possible free creature would have freely done in each set of possible circumstances, if fully specific; and that he had this knowledge at the creation. (An action is free in the required sense if not causally determined and not predetermined by God.) Propositions about what a creature would do in a set of circumstances (possible as well as actual) are commonly called “counterfactuals of freedom”, and God’s knowledge of them is called “middle knowledge” (Molina, On Divine Foreknowledge (Part IV of the Concordia); Plantinga 1974, IX).