Teleological argument

=== Thomas Aquinas ===
[[File:St-thomas-aquinas.jpg|thumb|upright|The fifth of Thomas Aquinas' proofs of God's existence was based on teleology.]]

Thomas Aquinas (1225–1274), whose writings became widely accepted within Catholic western Europe, was heavily influenced by Aristotle, Averroes, and other Islamic and Jewish philosophers. He presented a teleological argument in his ''[[Summa Theologica]]''. In the work, Aquinas presented five ways in which he attempted to prove the existence of God: the ''[[quinque viae]]''. These arguments feature only ''a posteriori'' arguments, rather than literal reading of holy texts.<ref>{{Cite book |last=Davies, Brian |url=https://books.google.com/books?id=TxrDzeKU2VsC&q=aquinas+teleological+argument+aristotle&pg=PA30 |title=The Thought of Thomas Aquinas |publisher=Oxford University Press |year=1992 |isbn=978-0-19-152044-0 |page=30, footnote 30}}</ref> He sums up his teleological argument as follows:

{{Blockquote|text=The fifth way is taken from the governance of the world. We see that things which lack knowledge, such as natural bodies, act for an end, and this is evident from their acting always, or nearly always, in the same way, so as to obtain the best result. Hence it is plain that they achieve their end, not fortuitously, but designedly. Now whatever lacks knowledge cannot move towards an end, unless it be directed by some being endowed with knowledge and intelligence; as the arrow is directed by the archer. Therefore, some intelligent being exists by whom all natural things are directed to their end; and this being we call God. |author=Thomas Aquinas|source=''Summa Theologica: Article 3, Question 2)''<ref name="Himma">Himma, Kenneth Einar (2006). [http://www.iep.utm.edu/d/design.htm#SH1b "Design Arguments for the Existence of God"], in James Fieser and Bradley Dowden, eds., ''The Internet Encyclopedia of Philosophy'', retrieved 8/24/08</ref>}}

Aquinas notes that the existence of [[final cause]]s, by which a cause is directed toward an effect, can only be explained by an appeal to intelligence. However, as natural bodies aside from humans do not possess intelligence, there must, he reasons, exist a being that directs final causes at every moment. That being is what we call God.<ref name="Himma" />