For my students

On monday, the course I teach goes into second gear: Normative Ethics. First out is the doctrine of ethical egoism. Ethical egoism, the idea that you should do what lies in your own self-interest, is distinct from psychological egoism, the idea that in fact you are only motivated by your own self interest. In its strong version, this latter view has it that you cannot be motivated by anything else. Genuine altruism is impossible. Psychological and ethical egoism are two very different things, it is said. One is about what is the case, the other is about what ought to be the case.

Now, consider that ought implies can. I.e. it cannot be the case that you ought to do something that it is impossible for you to do.

So, if you cannot be motivated by anything else than your own self-interest, it cannot be the case that you ought to be motivated by something other than your own self-interest.

So it would seem that from ought implies can and strong psychological egoism it follows that you ought to be motivated by your own self-interest.

But note that this is not what ethical egoism claims: Ethical egoism says that you ought to promote your own self-interest, not that you ought to be motivated by your own self-interest. And even if we cannot be motivated to promote the greater good, our actions can certainly promote the greater good. Psychological egoism does not even seem to bar the possibility that we intend to bring about other results, only that we cannot be motivated to do so.

So, since we can promote the greater good, it is logically possible that we ought to. But, if psychological egoism is true, it is only logically possible that we ought to promote the greater good by accident.

See you monday!