I am listening to a biography of C.S. Lewis as a book on tape. It has reached the time in his life when he was giving the radio lectures which would become Mere Christianity. That made reference to natural law.
Some months ago, I went to a lecture on the Ethical and Religious Directives for Catholic Healthcare Organizations. The presenter started off by talking about Catholic ethics originating in natural law. At the time, I meant to look into it, but didn't have time.
My brief beginning of looking into this led me to a discussion of deontology. When I was a college senior, I took a course in logic from a professor I liked who encouraged experimentation. Towards the end of the course, he gave worksheets to experiment with to explore the question of which of the rules of logic we had learned would work in a deontic ethical argument (Would modus ponens work on "If the baby is sleeping, be quiet"?) There wasn't enough time to explore that as fully as I wanted to. Every so often, I pull out some scrap paper and try to figure out what I can on this front. I don't know that I ever get very far, or save the work so that the next time I want to play with it, I am that much further along. I should work this out with someone and see where it leads. Recreational logic of ethics, anyone?