So what is your argument regarding ethics, Einstein?
I'm partial to Christine Korsgaard's neo-Kantian argument in
The Sources of Normativity. She begins by observing that human beings are reflective creatures: we have desires that can pull us one way or the other, but we also have the capacity to take a refelctive position, to step back from our desires and consider them as things in the world. When we take this reflective position, we can evaluate our desires and decide whether or not we have good reason to act on them. We take ourselves to have "good reason" if acting on a particular desire is in accord with the ethical committments that comprise our identity. For example, because of your identity as a professor, you might take yourself as having good reason to be well-prepared for your lectures, and because of my identity as a student I might take myself as having good reason to do all the required reading for my classes. If I don't do the reading and flunk out of school, my identity as a student will disintegrate. Under this view, feeling one's identity disintegrate is what it means to feel guilty.
So far, this is still a relativistic argument that provides no basis for morality. There's no reason to suspect that one identity is fundamentally superior to another. Korsgaard attempts to resolve this problem with an exceedingly clever argument: human beings from different cultures and backgrounds may have wildly different identities, but they are all essentially the same in that they
have an identity in the first place. All human beings need an identity because they all need some reason for choosing one desire over another. If we had no reason for doing anything at all, we wouldn't be human. Since having an identity is what it means to be human, anyone who has an identity must think that being human is valuable. If everyone values humanity, then there's a basis for some kind of universal deontological morality.
I don't think this this argument completely escapes the criticism of moral skeptics in the Benthamite tradition, but I like it because conceiving of morality as a function of identity is very useful in thinking about politics, both theoretically and practically.