Quinquae viae

The Quinquae viae, or Five Ways, are five proofs of the existence of God summarized by St. Thomas Aquinas in his Summa Theologiae. These proofs take the form of philosophical arguments:

The argument of the unmoved mover (ex motu).
- Some things are moved.
- Everything that is moved is moved by a mover.
- An infinite regress of movers is impossible.
- Therefore, there is an unmoved mover from whom all motion proceeds.
The argument of the first cause (ex causa).
- Some things are caused.
- Everything that is caused is caused by something else.
- An infinite regress of causation is impossible.
- Therefore, there must be an uncaused cause of all caused things.
The argument of contingency (ex contingentia).
- Many things in the universe may either exist or not exist. Such things are called contingent beings.
- It is impossible for everything in the universe to be contingent.
- Therefore, there must be a necessary being whose existence is not contingent on any other being(s).
The argument of degree (ex gradu).
- Various perfections may be found in varying degrees throughout the universe.
- These degrees of perfections assume the existence of the perfections themselves.
The argument of design (ex fine).
- All designed things have a designer.
- The universe is designed.
- Therefore, the universe has a designer.