The 60-Second Aquinas
Lesson
The Leap from Does to Ought
Aquinas Lesson for June 30, 1998
A critic of Aquinas’ first principle of Natural Law – that good ought to be done and evil avoided – said that there is a difference between the fact of doing good and the value of it. "It is impossible to derive normative judgements from metaphysical speculations," said Germain Griez. Ralph McInerny, in his book Ethica Thomistica, explains Griez’s point using Wheaties as an example. Griez would argue "there is something illicit in the passage from such sentences as ‘Wheaties are good for you’ to ‘You ought to eat Wheaties’" (Ethica Thomistica 50).
McInerny’s explanation of why Griez’s argument fails is very fine. I won’t try to imitate it in the space I have left.
However, here is the main point. Aquinas bases his moral philosophy on practical reason, which, like Artistotle, he gleans from metaphysical observations of an unchanging existence. That is, certain details in the world may change, but the undercurrent of human existence itself remains constant. This constancy comes from the Creator.
More simply put, for Aquinas, the fact that men by nature pursue good is not accident. It is the way it should be!
Explanation of The 60-Second Aquinas Lesson
