Of Turtles and God's Necessary Existence.

Just Thomism writes:

One way to consider the Five Ways:

a.) Resolve to only speak per se and universally or, as the Oxford translation puts it, to speak predicates of subjects that are commensurately universal (See Posterior Analytics, Bk 1 c. 4)

b.) Then ask 1.) What moves (actively)? 2.) what causes effectively? 3.) What is necessary? 4.) What is good, true, dignified, and the like? 5.) What directs?

We can, as others have pointed out, also ask “what exists” or “who understands”, though this is in fact part of 4.).

The obvious objection to this is that the Five Ways never mention what is per se and universally said. But this is implied in the denial of the infinite regress. The denial of such a regress is the same as saying that some feature of things is explained by something per se and first. Absent this, we just posit more turtles for the world to rest on.

And yes, asking this question does make it clear why “all call this being God”.

This is very helpful as I am working my way through Aquinas’ Commentary on the Posterior Analytics and I am lost in some very tall weeds. I hadn’t realized the importance of the ideas of "per se" and "universal."


So, basically, if we have infinite regress, all we have is an infinite bunch of specific, accidental explanations for the existence of something – one turtle after another. This doesn’t meet the definition of a “demonstration” - which is a necessary conclusion following from necessary premises - because no particular turtle is necessary.