Modern Theories I. Introduction Print section Natural Law , in ethical philosophy, theology, law, and social theory, a set of principles, based on what are assumed to be the permanent characteristics of human nature, that can serve as a standard for evaluating conduct and civil laws. It is considered fundamentally unchanging and universally applicable. Because of the ambiguity of the word nature, the meaning of natural varies. Thus, natural law may be considered an ideal to which humanity aspires or a general fact, the way human beings usually act.
Natural law is contrasted with positive law, the enactments of civil society.
The ancient Greek philosophers were the first to elaborate a natural law doctrine. The Stoics, especially the philosopher Chrysippus of Soli, constructed a systematic natural law theory. Every individual nature is part of the cosmos. To live virtuously means to live in accord with one's nature, to live according to right reason. Because passion and emotion are considered irrational movements of the soul, the wise individual seeks to eradicate the passions and consciously embrace the rational life.