Experience and Morality

I'm re-reading (or rather, re-beginning) moral philosopher and theologian Germain Grisez's 1964 book, Contraception and the Natural Law. I'm intrigued by Grisez's conception of the natural law (as distinguished from other Thomists who are not as closely aligned with the analytical movement in philosophy), and I'm also curious about his purely philosophical argument against contraception.

In the Introduction, he has some simple, straightforward thoughts on the place of experience in moral decision-making, and they are worth quoting here:

Moral judgment is concerned with the ideal, with what ought to be. The deliverances of experience are concerned only with the facts, with what is. If there were no divergence between the two, there would be no place for ethics. Experience with life can show us that something is not as it should be, that something should be changed. But experience itself does not tell us what to change [p. 4].

Exactly! Too many people base their moral decisions solely on their own experiences, without applying their rationality; Grisez's words here demonstrate the gaping error present in such practice.