Descriptive ethics in the context of "Moral relativism"

Normative ethics is the study of ethical behaviour and is the branch of philosophical ethics that investigates questions regarding how one ought to act, in a moral sense.

Normative ethics is distinct from metaethics in that normative ethics examines standards for the rightness and wrongness of actions, whereas meta-ethics studies the meaning of moral language and the metaphysics of moral facts. Likewise, normative ethics is distinct from applied ethics in that normative ethics is more concerned with "who ought one be" rather than the ethics of a specific issue (e.g. if, or when, abortion is acceptable). Normative ethics is also distinct from descriptive ethics, as descriptive ethics is an empirical investigation of people's moral beliefs. In this context normative ethics is sometimes called prescriptive (as opposed to descriptive) ethics. However, on certain versions of the view of moral realism, moral facts are both descriptive and prescriptive at the same time.

Moral reasoning is the study of how people think about right and wrong and how they acquire and apply moral rules. It is a subdiscipline of moral psychology that overlaps with moral philosophy, and is the foundation of descriptive ethics.

An influential psychological theory of moral reasoning was proposed by Lawrence Kohlberg of the University of Chicago, who expanded Jean Piaget’s theory of cognitive development. Lawrence described three levels of moral reasoning: pre-conventional (governed by self-interest), conventional (motivated to maintain social order, rules and laws), and post-conventional (motivated by universal ethical principles and shared ideals including the social contract).

Psychological egoism is the view that humans are always motivated by self-interest and selfishness, even in what seem to be acts of altruism. It claims that, when people choose to help others, they do so ultimately because of the personal benefits that they expect to obtain, directly or indirectly, from doing so.

This is a descriptive rather than normative view, since it only makes claims about how things are, not how they "ought to be" according to some. It is, however, related to several other normative forms of egoism, such as ethical egoism and rational egoism.

Evolutionary ethics is a field of inquiry that explores how evolutionary theory might bear on our understanding of ethics or morality. The range of issues investigated by evolutionary ethics is quite broad. Supporters of evolutionary ethics have argued that it has important implications in the fields of descriptive ethics, normative ethics, and metaethics.

Descriptive evolutionary ethics consists of biological approaches to morality based on the alleged role of evolution in shaping human psychology and behavior. Such approaches may be based in scientific fields such as evolutionary psychology, sociobiology, or ethology, and seek to explain certain human moral behaviors, capacities, and tendencies in evolutionary terms. For example, the nearly universal belief that incest is morally wrong might be explained as an evolutionary adaptation that furthered human survival.