An Aristotelian Ontological Argument (using the LBA)

1.) Act and potency are really divided and not just notionally distinct.  We can have a skill to play music when not playing.

2.) Act and potency are not correlatives. Potency depends on act to exist but not vice versa. Shown in three ways:

a.) Potency is defined relative to act but act is not defined (Metaphysics IX. esp. c. 6)

b.) If act as such depends on potency then act, as act, is potential. But they are really distinct (see 1).

c.) Potency depends on act intrinsically and in its logos but act does not so depend on potency (see 2a)

3.) If act and potency are not correlatives and are really distinct, an-act-that-lacks-all-potency  (pure act) is metaphysically and not just logically possible. In other words, when we say that pure act is “possible” we don’t just mean that we see no contradiction (and for all we know there might be one) but that we see that there is not a contradiction.*

4.) To prove that there are no contradictions in a necessary thing is to know it exists, in the same way that to prove there is no contradiction in denying the Fifth Postulate proves that Non-Euclidean quantities exist. Call this the Leibniz-Brentano Axiom. 

5.) Whatever lacks all potency is by definition necessary.

6.) Pure act exists.

*When apologetics seeks to prove that there are no contradictions in the dogmas of the faith, it arguably only establishes logical possibility.



  1. David said,

    August 19, 2016 at 11:48 pm

    Seems like a hybrid? It’s a cosmological argument to the degree that we know act and potency by observing motion. It’s ontological to the degree that we’re analyzing the necessity of the concept.

    • August 20, 2016 at 8:21 am

      This might be true of all OA’s, though the reference to observation only arises to support a premise. If you want to prove Plantinga’s modal OA, at some point you’re going to have to appeal to experience to ground the existence of possible worlds, e.g. “we see by looking at the world that many outcomes that could happen don’t happen”. Anselm’s OA is arguably based on his articulation of degrees of existence as laid out in Monologion (I’m not convinced of this, but I had a prof who insisted on it once and I never could refute his case). My argument can be taken as just Leibniz’s with the notion of perfection beefed up by an analysis of act-potency relations.

      • David said,

        August 20, 2016 at 10:08 pm

        I’m trying to figure out if Aquinas’s rejection of Anselm’s OA is relevant to this one. Have you discussed STA’s opinion of Anselm on the blog?
        I appreciate your writing! Always thought provoking.

  2. Lucretius said,

    August 20, 2016 at 5:12 pm

    I think I understand what you were trying to explain to me a while ago regarding reason and the passions: it’s similar as to how Chesterton in Orthodoxy argues that Christendom is the only religion that contains and can contain both the peacefulness of a monk and the fierceness of the knight without contradiction, yes? We want a lion to be fierce, strong, and proud, but fierce, strong, and proud in the savanna, not in a suburban playground.

    Thank you 🙂

    Christi pax,


    • Lucretius said,

      August 20, 2016 at 5:14 pm

      *contradiction or tenuous

%d bloggers like this: