From another reader;
To hell with self-interest! I’m a sophomore at the University of Pennsylvania and cringed when reading the Georgetown student’s derivation of morality from self-interest.
Self-interest does not account for any of the most important things in life. Why do soldiers die for their country? Why would anyone die for anything, if self-interest reigned? A parent for a child? A husband for a wife?
Sane people will acknowledge that these actions are “good”. But they glorify a radical rejection of self-interest for a higher purpose. As your first correspondent correctly pointed out, morality cannot be explained without reference to an Absolute — i.e., God. You cannot say, `this is good’ and `that is bad’ without implicitly relying on a standard of perfect goodness.
Suppose you just bought a $100 pair of Gucci shoes. You’re walking along and see a child drowning in a lake. You don’t have time to take off your shoes, and they’ll be ruined if you jump in. Do you jump in, save the child, and lose your hundred bucks? or do you continue walking, let the child drown, and preserve your investment?
Self-interest seems to suggest the latter. Conscience, on the other hand, demands the former. The self-interest theory may sometimes account for why we don’t do bad things. But it doesn’t account for why we do good things. It doesn’t account for charity at all. Morality often involves an overcoming of self-interest.
Moral reality doesn’t point backward to our socio-historical development; it points upward to a higher, greater purpose that gives meaning to life. It is a purpose worth living and dying for.
(You should read Prof. Peter Kreeft’s “A Refutation of Moral Relativism”. It’s short and sweet.)