Teleology is the philosophical attempt to describe things in terms of their apparent purpose, directive principle, or goal. A purpose that is imposed by a human use, such as that of a fork, is called extrinsic. Natural teleology, common in classical philosophy but controversial today, contends that natural entities also have intrinsic purposes, irrespective of human use or opinion. For instance, Aristotle claimed that an acorn's intrinsic telos is to become a fully grown oak tree.
Though ancient atomists rejected the notion of natural teleology, teleological accounts of non-personal or non-human nature were explored and often endorsed in ancient and medieval philosophies, but fell into disfavor during the modern era (1600–1900).
In the late 18th century, Immanuel Kant used the concept of telos as a regulative principle in his Critique of Judgment. Teleology was also fundamental to the speculative philosophy of Georg Wilhelm Friedrich Hegel.
Contemporary philosophers and scientists are still actively discussing whether teleological talk is useful or accurate in doing modern philosophy and science. For instance, in 2012, Thomas Nagel proposed a neo-Darwinian account of evolution that incorporates impersonal, natural teleological laws to explain the existence of life, consciousness, rationality, and objective value.
The word teleology builds on the Greek , telos (root: τελε-, "end, purpose") and , logia, "a branch of learning". The German philosopher Christian von Wolff coined the term (in the Latin form "teleologia") in 1728 in his work Philosophia rationalis, sive logica.
In western philosophy, the term and concept of teleology originated in the writings of Plato and Aristotle. Aristotle's Four Causes give special place to each thing's telos or "final cause." In this, he followed Plato in seeing purpose in both human and sub-human nature.