The following is Thomas Aquinas’ cosmological argument from contingency I used in the VT debate on the existence of God. This version of the cosmological argument can be traced back to antiquity originally advocated by Plato and Aristotle. For my method of argumentation please see: VT–My Method of Argumentation.
- What we observe and experience in our universe is contingent.
- A network of causally dependent contingent things cannot be infinite.
- A network of causally dependent contingent things must be finite.
- Therefore, There must be a first cause in the network of contingent causes.
In this context, what I mean by contingent is that if X is contingent then X owes its existence to something else. For a thing that has the potentiality of movement cannot actualize its own potential; some other thing must cause it to move. The universe consists of a network of causes. A was caused by B, but only because B is caused by C, and so on. We know of nothing that spontaneously initiates its own causal activity. (Even supposed quantum indeterminacy requires a state of affairs, or preceding causal conditions, such as the governance of the laws of nature, for the event to occur). This is a hierarchical network of causation and not temporal. Note that nothing here turns on our having to know about everything.
*Does this suffer from the fallacy of composition? I think not. Composition only appears when certain predicates are applied to the universe. For instance, if I have a mosaic of triangles does that mean the mosaic is in the shape of a triangle? Obviously not. However, if I have a mosaic and all the tiles are yellow is the whole mosaic yellow? Well, yes. If these contingencies are predicates likened to the example of color then no fallacy is present. Also, to deny this premise is to suggest that each particle in the universe is metaphysically necessary, but that hardly seems to be true.
Additionally, this argument stands completely independent of any principle of sufficient reason. Leibniz and Samuel Clarke were the first to use the principle of sufficient reason for a universal first premise, which is inapplicable here.
Concerning premise 2: This network of contingent causes cannot go on to infinity. In such a series, the intermediate causes have no power of their own but are mere effects of the preceding causes. It doesn’t matter whether there is an actual infinite set of contingencies because such a set could not move from potentiality to actuality on its own accord. For instance, a train with an infinite set of boxcars cannot move without a locomotive.
Also, consider Hume’s objection stating that you can never get an infinite cause from a finite effect. Hume argued that if you can explain the subsets [boxcars] then you can explain the whole [infinite] set. Paul Edwards follows Hume along similar lines, Edwards argues that each one in the series fully explains the one that depends on it. Every member is genuinely the cause of the one that follows it. However, in explaining the first member of a set one must go out of the set to explain it. An infinite series never gets out of the set. Thomas is willing to grant an infinite set of causes in fieri (in process) but that’s not what Thomas is concerned about. What the argument applies to and describes is the world, in esse causation (essence or being), which cannot be actually infinite.
Premise 3 is the logical conclusion from Premise 2.
Thus, the reason that any contingent thing exists at all (and, in particular, the world which we are part) is that it is a contingent causal consequence of an absolutely necessary being, a being which itself could not have failed to exist. Only two things are possible explanations: abstract objects or minds. However, abstract Platonic objects stand in no causal capacities. The only option remaining is a mind. By implication: we remain with an uncaused cause, which must be spaceless, timeless, and transcendent. Thus, to ask the question, “What caused the first uncaused cause?” is non-sensical.
*I did not mention this point in the debate due to time restriction but it was included in my notes.
 Focus on a series in which a member’s existence is explained by the preceding cause.
 Timothy O’Connor, Theism and Ultimate Explanation (Oxford, UK: Blackwell, 2008), 65.