Concept
The Quinque viæ (Latin for "Five Ways") (sometimes called "five proofs") are five logical arguments for the existence of God summarized by the 13th-century Catholic philosopher and theologian Thomas Aquinas in his book Summa Theologica. They are: the argument from "first mover"; the argument from universal causation; the argument from contingency; the argument from degree; the argument from final cause or ends ("teleological argument"). Aquinas expands the first of these – God as the "unmoved mover" – in his Summa Contra Gentiles. Aquinas did not think the finite human mind could know what God is directly, therefore God's existence is not self-evident to us, although it is self-evident in itself. On the other hand, he also rejected the idea that God's existence cannot be demonstrated: although it is impossible to give a so-called propter quid demonstration, going from the causes to the effects; nevertheless the proposition God exists can be "demonstrated" from God's effects, which are more known to us, through a so-called quia demonstration. However, Aquinas did not hold that what could be demonstrated philosophically (i.e. as general revelation) would necessarily provide any of the vital details revealed in Christ and through the church (i.e. as special revelation), quite the reverse. For example, while he would allow that "in all creatures there is found the trace of the Trinity", yet "a trace shows that someone has passed by but not who it is." The first three ways are generally considered to be cosmological arguments. Aquinas omitted various arguments he believed to be insufficient or unsuited, such as the ontological argument made by Anselm of Canterbury. A summary version of the Five Ways is given in the Summa theologiae. The Summa uses the form of scholastic disputation (i.e. a literary form based on a lecturing method: a question is raised, then the most serious objections are summarized, then a correct answer is provided in that context, then the objections are answered).
