The Cosmological Argument is an a posteriori argument, meaning it follows on after evidence. It is an argument based on evidence. In this case, the evidence presented to us is in the form of observations of the world around us, observations of motion, causation and contingency.
Aquinas essentially argues that all of these observations need explaining. Motion needs and unmoved first mover, causation needs and uncaused first cause and contingency needs a necessary being. Aquinas concludes that such an explanation is God.
For many people, this basis in observation offers strength to the argument. We can all see motion and causation, we can all understand that things are contingent, and it leads us to ask those questions from the first post – why are we here? Why is there something rather than nothing?
However, this basis in observation, this a posteriori nature brings with it a weakness.
Let’s return to the first way. We can accept that some things are in motion. We can accept the idea that things can’t move themselves so need to be moved by other things. We can accept this because we see it happening around us. We may even accept that this regressive sequence of movers cannot continue ad infinitum. (Now we know this is a debatable point, but for now let us assume that it is correct.)
We are now at the point of accepting the idea of an unmoved first mover and we accept this on the basis of the evidence we see around us.
However, notice what then happens in the Thomist argument. Aquinas says that this unmoved first mover is God.
Here we have a problem – the argument is based on evidence, but where is the evidence to say that his unmoved first mover is God? Even if we accept the argument works until this final point (and we know that it might not) it seems a big jump beyond what the evidence tells us to say that this unmoved first mover is God.
Furthermore, even if we accept Aquinas’ conclusion that this is God, is this really what we mean by God? According to the Thomist argument, we do we know about God?
- unmoved first mover
- uncaused first temporal cause
- sustainer of causation, motion and existence
- the explanation for why there is something rather than nothing
Does this sound like the God Christians describe? A loving father, creator and redeemer of the universe, one to whom prayer and worship are offered, a forgiving God who wishes to be in loving harmony with his creation? For many Christians, and other religions for that matter, God is a personal God, a God with whom communication and relationship are possible. Maybe the God of the Cosmological Argument is not really what “everyone calls God” after all.