I’m sure that is a very good book, but from looking on amazon.co.uk, the subject matter is more general philosophy and not really ethics, in the sense that ethics is the “good” or ideal behaviour.
If not, anyway, I’m not too interested in the existing systems except in passing. I have consulted “The Elements of Moral Philosophy” by Rachels.
justice and duty (which cover mutually incompatible moral systems)
We have a duty to be just.
it leaves out dogmatic moral code
I haven’t claimed to describe the entirety of morality in three concepts. However, I see them as the core of ethics, the good.
arbitrary moral norms that emerge from human culture
Are norms really arbitrary? Each culture lives in a physical place in a political and geographical environment, that has its own pressures on the population. So, there are norms to cope with local pressures or conditions. A norm is there to turn a potentially competitive situation into a cooperative one. On the other hand, like you could say, there are other reasons for introducing norms, such as the dark side of religion.
It says nothing about the framework needed to justify imposing a moral system in the first place.
The framework that makes sense is cooperation with interdependence. These conditions can plausibly be shown to give rise to a modern evolved moral psychology of helping, fairness, obligation, the social contract etc.
