Human nature refers to the distinguishing characteristics—including ways of thinking, feeling, and acting—which humans tend to have naturally.
The questions of whether there truly are fixed characteristics, what these natural characteristics are, and what causes them are among the oldest and most important questions in philosophy and science. The concept of human nature is traditionally contrasted not only with unusual human characteristics, but also with characteristics which are derived from specific cultures, and upbringings. The "nature versus nurture" debate is a well-known modern discussion about human nature in the natural sciences.
These questions have particularly important implications in economy, ethics, politics, and theology. This is partly because human nature can be regarded as both a source of norms of conduct or ways of life, as well as presenting obstacles or constraints on living a good life. The complex implications of such questions are also dealt with in art and literature, the question of what it is to be human.
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.