Today we considered Thomas Aquinas' account of natural law. We saw that Aquinas is committed both to the view that being good is a kind of soul development and that the world contains a natural moral law. The natural law begins with the principle that we must pursue the good. It builds on that to demand that we preserve ourselves, act in accordance with our natures, and also act as social beings. Aquinas thinks that these principles, if correctly understood, will lead to moral rules that apply everywhere and to everyone, rules against murder, theft, adultery, and so on.
We considered a very interesting case for Aquinas: the case of Abraham. Abraham is commanded to sacrifice his son, and Abraham never complains or says that it is immoral. Now Aquinas is committed to the view that the natural law forbids murder, and yet Abraham is ordered to kill his son - isn't that murder? Aquinas' philosophically interesting, if not emotionally satisfying, point is that if we don't think it is wrong when we die of natural causes, then we are already committed to the view that we live and die at God's will, and that God is not robbing us of anything if he allows us to die. So if it is up to God whether Isaac lives or dies, then it is not wrong for God to make Isaac die. So if there is nothing wrong in the first place, why is it more wrong if Abraham carries out an act which is not wrong? To put it very simply, if Isaac's life belongs to God, why is it wrong for God to dispose of it in any way he thinks good?