[From Latin natura: the character or course of things.]
(metaphysics) The idea that the universe operates according to its own laws, without intervention by any gods (opposed to theism and spiritualism, but compatible with deism).
(ethics) The view that core human values (food, water, shelter, safety, psychological closeness, knowledge, etc.) are based on the characteristics of the human organism. For example, existentialism could be considered a humanistic form of individualism, but it differs from many other forms of humanism in denying ethical naturalism.
(aesthetics) The theory that the purpose of art (especially literature) is to present human experience "as is" without evaluation or the projection of ethical ideals (historically, naturalism developed in reaction to romanticism).