As far as I can tell, there are three major problems in ethical thinking today:

1. Disconnecting ethics from happiness and therefore thinking that personal well-being and pleasure have nothing to do with ethics.
2. Hedonism: The idea that right and wrong is only a matter of what leads to the highest personal pleasure. In social ethics, this means allowing people to do whatever they think/feel will make them feel the best. We might call this unscientific utilitarianism (because it isn’t based upon actual knowledge of what is good for the individual or collective human organism.
3. The is/ought problem: That since knowledge is all descriptive, no understanding of what is can lead to a conclusion about what one ought to do.

In my opinion, all three of these problems are solved in one way or another by Mortimer Adler’s one self-evident moral premise: We ought to desire whatever is really good for us and nothing else.

Below are the paragraphs where he introduces the axiom in his book, 10 Philosophical Mistakes:

The two distinctions that we now have before us, distinctions generally neglected in modern thought—the distinction between natural and acquired desires, or needs and wants, and the distinction between real and merely apparent goods—enable us to state a self-evident truth that serves as the first principle of moral philosophy. We ought to desire whatever is really good for us and nothing else.

The criterion of self-evidence, it will be recalled, is the impossibility of thinking the opposite. It is impossible for us to think that we ought to desire what is really bad for us, or ought not to desire what is really good for us. The very understanding of the “really good” carries with it the prescriptive note that we “ought to desire” it. We cannot understand “ought” and “really good” as related in any other way.[1]

While Adler’s claim is presented as an axiom, a truth about which one cannot accept the opposite proposition, it can probably only be accepted once it is properly understood. Here are some questions to help us think it through:

1. Is it possible for there to be desires that are bad for us?
2. Are there desires that are good for us but desired wrongly?
3. Are there desires that are more important than others?
4. We desire food, but is there a reason to desire food?
5. We desire to live, but is there a reason we desire to live?
6. We desire pleasure, but is there a reason we desire pleasure?
7. We desire sex but is there a reason for sex?

If Adler’s axiom is axiomatic, we have a proposition upon which to build our ethics, dispute them as our understanding of human nature advances, and upon which to build theological ethics for those who accept divine revelation about the purpose and nature of humanity.

References

[1] Mortimer Jerome Adler, Ten Philosophical Mistakes (New York: Macmillan, 1985), 90-91