The Cosmological Argument According to Aquinas

The Cosmological Argument

The Cosmological argument for God’s existence argues from the ‘cosmos’ or universe itself.  It is therefore an A Posteriori argument – it is based on our experience of the universe and works up to God as a first cause.

The basis of the argument is this…

  • Everything in the universe is caused by something else – our universe is made up of a chain of causes and effects.
  • If everything has a cause, we could infinitely trace back cause and effect – infinite regression.
  • Infinity cannot be possible, therefore there must be a first cause.
  • The first cause of the universe is God

Aquinas’ Five ways

Catholic theologian and philosopher Thomas Aquinas developed Five Ways to argue for Gods existence…

  1. The argument from Motion
  2. The argument from Causation
  3. The argument from contingency and necessity
  4. The argument from beauty
  5. The argument from design

The first three of these arguments are cosmological.

The first of Aquinas’ five ways is from motion. Through motion in the universe, we can see that things need to be caused, and that there must be an uncaused cause. Aquinas meant more than just movement, eg. movement of the planets. Motion for Aquinas also refers to the movement from potentiality to actuality. For example, a cup of tea may be actually hot, but potentially cold. When it makes the motion to become a cold cup of tea, it has moved from potentially being cold to actually being cold. This was the motion to which Aquinas referred.

The second of Aquinas’ five ways was the argument from causation. Everything in the world has a cause. Therefore, there must be a first cause – this we call God.

The argument from contingency and necessity (the third way) is slightly more complex to understand. Aquinas identified the universe to be full of contingent things – that is, things which are dependent on other things for their existence. For example, as human beings, we are dependent upon our parents.  If there was once a time when there was nothing, a necessary being had to create something from nothing.  The argument therefore suggests a necessary being to bring contingent beings into existence, and this we call God.