As formulated by Thomas Aquinas, the uncaused cause argument is stated as follows:
- "Nothing is caused by itself. Every effect has a prior cause. This leads to a regress. This has to be terminated by a first cause, which we call God."
Many of the responses to the Unmoved mover argument also apply to this one:
One can argue that the conclusion "God is the first cause" contradicts the premise "everything has a cause", and that the first cause argument is therefore self-contradictory.
It can, however, be restated as a reductio ad absurdum, to make the contradiction a desirable feature:
- Premise: every event has a cause.
- Premise: there can be no infinite regress.
- Premise: there exists some event e0.
- From (1) and (3), it follows that e0 has a cause e1, which in turn has a cause e2, and so on, in an infinite regress.
- From (2) we know that there can be no infinite regress, which contradicts (4).
- Therefore, at least one of the premises must be false.
If we reject premise 1, that every event has a cause, then there must be at least one uncaused cause, which can be called "God".
Why call it God?
Even if we accept the argument from first cause, the conclusion is still problematic: the word "God" carries a lot of undesirable cultural baggage, denoting an intelligent being. If the ultimate cause of our universe turns out to be, say, a random vacuum fluctuation, then that would be "God" by Aquinas's definition, but to call this phenomenon "God" would be misleading. It also can be noted that if for some reason there did have to be a first cause, we currently do not currently know what which leads to the "God of the gaps" idea.
- Who created God?
- Pairs of virtual particles are created (and annihilated) all of the time, in vacuum, out of literally nothing, with no prior cause. This contradicts Aquinas's premise.
- Even if there is an infinite regess of causes, so what? The human mind is uncomfortable with the concept of infinity, but reality has no obligation to make us comfortable.