Teleology (from τέλος, telos, 'end,' 'aim,' or 'goal,' and λόγος, logos, 'explanation' or 'reason') or finality is a reason or an explanation for something which serves as a function of its end, its purpose, or its goal, as opposed to something which serves as a function of its cause. In the late 18th century, Immanuel Kant used the concept of telos as a regulative principle in his Critique of Judgment (1790).