Memoria College tutor Thomas Cothran, writing at Eclectic Orthodoxy, about St. Thomas Aquinas’ position on the problem of predestination:
God causes all of our actions, including our acts of choosing. He does not merely give mankind the power of choice, he causes the act of choosing itself. We are mere instruments of God’s will. Such is the view of St. Thomas Aquinas. But St. Thomas also believes that human beings choose freely, and that the dependence of human volition in its every movement on God does not violate human freedom. On its face, St. Thomas’ view appears paradoxical, even contradictory. And yet a number of recent religious thinkers appeal to the medieval Dominican in their own attempts to reconcile divine providence and human freedom.
The discussion in the over fifty responses to the article is also worth reading. You can read it here.