The Catholic House Divided: Thomist and Molinist

Even within a single communion the question splits. The Augustinian inheritance is the baseline all Western positions argue from. Within Catholic theology two schools are permitted and unreconciled. The Thomist account, following Thomas Aquinas and later the Dominican Domingo Banez, holds that God's grace is intrinsically efficacious, it infallibly moves the will it is given to, yet does so in a way that leaves the act genuinely free, because God moves each thing according to its nature. The Molinist account, devised by the Jesuit Luis de Molina in his Concordia of 1588, introduces middle knowledge: God knows what every possible free creature would freely do in every possible circumstance, and providentially arranges circumstances accordingly, so that grace is efficacious without overriding a freedom that could have refused.

The dispute grew heated enough that around 1600 Rome convened the Congregatio de Auxiliis to judge between the schools, and in the end declined to condemn either. Both remain live: the Molinist appeal to middle knowledge has been revived in recent decades by analytic philosophers of religion. The Tridentine definitions of the Council of Trent set the outer bounds all Catholic positions keep within, affirming both grace's priority and the reality of free cooperation.