Key People:
René Descartes
St. Anselm of Canterbury
Related Topics:
ontology
existence of God

ontological argument, Argument that proceeds from the idea of God to the reality of God. It was first clearly formulated by St. Anselm in his Proslogion (1077–78); a later famous version is given by René Descartes. Anselm began with the concept of God as that than which nothing greater can be conceived. To think of such a being as existing only in thought and not also in reality involves a contradiction, since a being that lacks real existence is not a being than which none greater can be conceived. A yet greater being would be one with the further attribute of existence. Thus the unsurpassably perfect being must exist; otherwise it would not be unsurpassably perfect. This is among the most discussed and contested arguments in the history of thought.

This article was most recently revised and updated by Brian Duignan.
Related Topics:
existence of God

cosmological argument, Form of argument used in natural theology to prove the existence of God. Thomas Aquinas, in his Summa theologiae, presented two versions of the cosmological argument: the first-cause argument and the argument from contingency. The first-cause argument begins with the fact that there is change in the world, and a change is always the effect of some cause or causes. Each cause is itself the effect of a further cause or set of causes; this chain moves in a series that either never ends or is completed by a first cause, which must be of a radically different nature in that it is not itself caused. Such a first cause is an important aspect, though not the entirety, of what Christianity means by God. The argument from contingency follows by another route a similar basic movement of thought from the nature of the world to its ultimate ground.

This article was most recently revised and updated by Brian Duignan.