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Normative ethics is distinct from meta-ethics in that the former examines standards for the rightness and wrongness of actions, whereas the latter studies the meaning of moral language and the metaphysics of moral facts. Likewise, normative ethics is distinct from applied ethics in that the former 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 the latter 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 meta-ethical view of moral realism, moral facts are both descriptive and prescriptive at the same time.
An adequate justification for a group of principles needs an explanation of those principles. It must be an explanation of why precisely these goals, prohibitions, and so on, should be given weight, and not others. Unless a coherent explanation of the principles (or demonstrate that they require no additional justification) can be given, they cannot be considered justified, and there may be reason to reject them. Therefore, there is a requirement for explanation in moral theory.
Most traditional moral theories rest on principles that determine whether an action is right or wrong. Classical theories in this vein include utilitarianism, Kantianism, and some forms of contractarianism. These theories mainly offered the use of overarching moral principles to resolve difficult moral decisions.