 He sketched these in "The Examined Life" as a four-layer structure.Its fundamental layer is the Ethic of Respect, essentially the deontological ethic of individual rights defended in "Anarchy, State, and Utopia" as well as in "Invariances", where it becomes the functional "core" of ethics.Evolution has selected us to abhor doing certain things to others and to abhor having those things done to ourselves, and this abhorrence gets systematized in groups of mutual benefit by moral codes that protect individual rights and duties.