The concept of nature as a standard by which to make judgments is traditionally said to have begun in Greek philosophy, at least as regards the Western and Middle Eastern languages and perspectives which are heavily influenced by it.
The teleological approach of Aristotle came to be dominant by late classical and medieval times. By this account, human nature really causes humans to become what they become, and so it exists somehow independently of individual humans. This in turn has been understood as also showing a special connection between human nature and divinity. This approach understands human nature in terms of final and formal causes. In other words, nature itself (or a nature-creating divinity) has intentions and goals, similar somehow to human intentions and goals, and one of those goals is humanity living naturally. Such understandings of human nature see this nature as an "idea", or "form" of a human.
However, the existence of this invariable and metaphysical human nature is a subject of much historical debate, continuing into modern times. Against this idea of a fixed human nature, the relative malleability of man has been argued especially strongly in recent centuries—firstly by early modernists such as Thomas Hobbes and Jean-Jacques Rousseau. In Rousseau's Emile, or On Education, Rousseau wrote: "We do not know what our nature permits us to be". Since the early 19th century, thinkers such as Hegel, Marx, Kierkegaard, Nietzsche, Sartre, structuralists, and postmodernists have also sometimes argued against a fixed or innate human nature.
Charles Darwin's theory of evolution has changed the nature of the discussion, supporting the proposition that mankind's ancestors were not like mankind today. Still more recent scientific perspectives—such as behaviorism, determinism, and the chemical model within modern psychiatry and psychology—claim to be neutral regarding human nature. As in much of modern science, such disciplines seek to explain with little or no recourse to metaphysical causation. They can be offered to explain human nature's origins and underlying mechanisms, or to demonstrate capacities for change and diversity which would arguably violate the concept of a fixed human nature.