Background Assumptions of the CA
The CA makes 3 types of assumption: ontological (about existence), epistemological (about knowledge) and semantical (about meaning).
Onotological Assumption: that existence has meaning, and that 'God' is the best explanation for why there is something rather than nothing.
Epistemological Assumption: that we can have knowledge about the origins of the universe.
Semantical Assumption: it is sometimes argues that the CA derives an actual explanation of the world from a possible one, i.e. 'possible' becomes semantically equivelant to 'actual' so the statement 'God is a possible first cause of the universe' becomes 'God is the actual first cause of the universe'.
Aquinas' Argument in Aristotle's Philosophy
Aquinas was heavily influenced by the teachings of Aristotle who taught that everything that exists can be explained by 4 causes (matter, form, efficient cause and the final cause/purpose).
By 'cause' Aristotle means 'explanation', only the 'cause' in 'efficient cause' means what we understand 'cause' to mean.
Aristotle also argued that the 4 causes themselves needed to be explained - what begins the process of motion and change? His answer was that there must be a First Efficient Cause, which he calls the Prime Mover.
The Prime Mover cannot be made of matter, otherwise it would need an efficient cause, so the Prime Mover must be non-material and exist outside space and time.
This Prime Mover did not beng motion and change with some kind of 'push' like a domino effect, but rather by being a perfect Final Cause which all things are attracted to because of its perfection.
Aquinas' Argument in Observation
The CA is an a posteriori argument - meaning it is based on observation.
Aquinas' CA is based on 3 main observations:
- That things move and are changed
- That things in the world are subject to the laws of cause and effect
- That the universe is contingent
Aquinas argues back from these observations to the supopsed cause of them - the conclusion is that there must be a being who created the universe and who is the source of movement and change.
"God's effects are enough to prove that God exists, even if they may not be enough to help us comprehend what He is." - Aquinas; 'Summa Theologica'
Aquinas' First Way: The Argument from Motion
In the Summa Theologica Aquinas develops 5 arguements (5 'Ways') for the existence of God. The first 3 of these are the CA.
The First Way - The Argument from Motion:
P1 - some things are in motion, others are at rest
P2 - something at rest is in a state of potential
P3 - something potential can be moved only by something actual
P4 - If matter cannot move itself, then we have no explanation for why some things are now in motion
P5 - there cannot be an infinite chain of past movers; otherwise there would be no motion now
C1 - so there must have been a First Unmoved Mover
C2 - This was God
The Second Way: The Argument from Efficient Cause
P1 - there is an efficient cause for everything
P2 - nothing can be the efficient cause of itself
P3 - there cannot be an infinite regress of efficient causes; otherwise there would be no explanation of the present
C1 - so there must be an Uncaused Cause, which causes everything to happen but is not caused itself
C2 - this is God
The Third Way: The Argument from Contingency and N
P1 - everything is contingent
P2 - then at some point there was nothing, because there must have been a time when nothing had begun to exist
P3 - If there was once nothing, nothing could come from it
P4 - therefore something must exist necessarily, otherwise nothing would exist now
P5 - everything necessary must either be caused or uncaused
P6 - the series of necessary being cannot be inifinite, or there would be no explanation of the series
C1 - therefore there must be some uncaused being which has necessary existence
C2 - this is God