What critical assumption underlies ethical egoism?

The critical assumption underlying ethical egoism is that individuals *shouldact in their own self-interest, and that doing so is morally right. Ethical egoism posits that promoting one's own well-being is the proper goal of moral action. It assumes that each individual is the best judge of what is good for themselves and that pursuing their own self-interest will ultimately lead to the best outcome, either for the individual or, according to some proponents, for society as a whole. It's important to differentiate ethical egoism from psychological egoism, which is a descriptive theory stating that individuals *areinherently motivated by self-interest. Ethical egoism, on the other hand, is a normative theory that claims individuals *oughtto be motivated by self-interest. This 'ought' is the core assumption; it is the belief that prioritizing one's own well-being is not just natural but also morally justifiable.