A Response to Ben Bavar on Act and Potency, Part 1

Ben Bavar, a cohost of the Real Atheology Podcast, and Matthew Su, one of the admins for the Thomism Discussion Group on Facebook, have been having a back and forth on Bavar’s critique of Feser’s presentation of the argument from motion from his book Five Proofs of the Existence of God. Their discussion has given them occasion to discuss the Thomistic act/potency principle, which I have also been writing about recently in my posts on the 24 Thomistic Theses (see here and here). As such, I thought I might to enter into the conversation by offering a brief response to Bavar.

To do so will first require recapitulating some of Bavar and Su’s dialogue up to this point. It begins with Bavar’s video on “Stage 1 of Feser’s Argument from Motion.” The first stage of the argument, on which Bavar is focusing in this video, argues from the reality of motion/change to the existence of a purely actual first cause/unactualized actualizer/unmoved mover. Bavar begins by objecting to the fourth premise of Feser’s formal argument, which states that “No potential can be actualized unless something already actual actualizes it (the principle of causality)” [1]. Bavar notes that, for Feser, a potential cannot actualize anything because it is merely potential; but Bavar responds that this “rests on a confusion, because although a potential is unactualized . . . it is by definition the case that a potential is still an actual thing . . . . An unactualized potential is an actual thing.” As an example he notes the behavioral disposition of a baby to cry when its pacifier is taken away. When the pacifier is not actually taken away, the baby retains a potential to cry when it is. But this potential is more than a mere ability, it is an active disposition. And this disposition is actual, not merely potential. Similarly, he suggests, hot coffee is not actually cold, but it does actually have or possess a potential to be cold; and so the coffee’s potential to be cold must be something actual, an actual feature.

Next comes Su’s response, part of which I’ll quote here: “First, he thinks that even if a potential is not actualised, nevertheless [it] has actuality. This is true in a sense, but this truth is what the Thomas means by the ‘combination’ of potency and act in real things: The respect in which ‘a potential’ is potential (like hot tea’s potential to be cold) is not actual or real — the potential coldness in the tea can’t chill your finger — but the tea is not pure potency: it has some actuality (i.e., that of being tea of a certain temperature). It is not from this lack that the actuality of coldness derives, but from the potential for coldness being actualised by something else (like the surroundings which absorb the heat, and actualise the potential for coldness) . . . . He thinks that potentials can be caused by other potentials, since potentials are for him a kind of actuality. So the terminus to a regress can be potential, even pure potential. This is really confused: Potential is an orderedness-toward act, and hence pure potential, considered apart from all act (even that toward which it is ordered), does not exist at all. He thinks that the terminus to a regress of actualizes could be something that lacks an actualised potential to exist, yet have other potentials, which he paints as an alternative to pure act, and the combination of act and potency. But whatever ‘has,’ as a part of its mode of being, potentials, is a combination of potency and act. Whatever is composite depends upon parts to exist, and whatever is dependent for its existence upon something else, has a potential-for existence (i.e., in the parts considered apart from it), which is actualised. So if a thing ‘has’ any potential in any respect (i.e., is not Pure Act), its existence needs to be actualised by an actuality not identical to its own. So this is not a real alternative to Feser’s disjunct, being just another combination of potency and act, presupposing a further actualiser” [2].

Then we get Bavar’s next reply: “Your answer to my first question suggests that you don’t distinguish like I do between potential coldness and the potential for coldness. That may have something to do with the way you think of potential’s relation to actuality. I can see the intuitive plausibility of the thought that potential coldness is not an actual thing, because it’s merely a potential, not an actual, instantiation of coldness. But I think even this inference is suspicious, for not being an actual thing *of any sort* doesn’t follow from not being actual *coldness*, and so not being actually able to chill fingers. It’s even less plausible that the potential for coldness is not an actual thing *of any sort*, because it is a capacity for coldness. Capacities (as well as dispositions) are prima facie actual things, and their actuality is evidenced by their apparent contribution to what things do in the world. Sure, capacities for coldness, just like potential coldness, may be unable (on their own) to chill fingers. But I do think they’re actual, and by Thomistic reasoning this means they may well have actualizing powers. My suggestion is that potentials have the ability to actualize some potential or other, not that, say, the potential for coldness necessarily has the ability to actualize other potentials for coldness. Capacities don’t just have actuality in the sense that they are combined with the actuality of their bearers; they don’t just “have” their bearers’ actuality, but rather they have actuality of their own. They are themselves actual, just like their bearers are actual” [3].

And one last response from Su: “It seems that your concept of potency as ‘capacity’ breaks down under analysis into an act/potency composite. You say that a capacity is in some sense actual. Let us grant this. But in order to be a capacity, it must also ‘not-be’ in a certain way, for a capacity is not ‘capacious’ in virtue of having already been realised. That respect in which it “is-not-X, but-directed-toward-X,” is its potency, the respect in which it ‘actually is’ is its act, and these respects cannot be the same. But in this case, it seems you have merely reproduced a further act/potency composite. It’s still not an alternative to Feser’s disjunct, and all you’ve done is introduced a superfluous ‘act’ to the ‘capacity,’ as distinct from the act of the substance in which it resides. Much easier to say that a potency is not, qua potency, in act, as I have done” [4].

Finally, Bavar has written a whole post on the Real Atheology blog replying to Su’s points. As a side note I should mention that their discussion covers a number of topics beyond just act and potency, but the latter is what I’m going to be focusing on here, or at least trying to. Also, I’ve exchanged a few more brief comments with Bavar over social media, which I’ll also bring up where relevant.

Now that we’ve been brought somewhat up to speed, we can begin an initial assessment. Bavar argues that a potential is in some sense actual, i.e. is actually existing, and hence has actualizing capabilities, such that a potential can actualize another potential. This means that a crucial premise in Feser’s argument — that a potential cannot be actualized by a potential but only by something already actual — fails. Except, I’m not exactly sure how this is supposed to work, even if Bavar is correct about potentials being actual. For if potentials just are actual, this need not pose a significant problem to the essence of the premise, which is that potentials can only be actualized by what is actual. It is still the case that actualization requires an actualizing agent, which is all the premise needs to succeed, so far as I can see.

But, getting beyond Feser’s argument in particular, is Bavar correct to say that a potential is something actual? As I understand it, Bavar’s argument can basically be summarized as something like this:

  1. For a potential to do the work the Thomist wants it to, it must be real
  2. But whatever is real, must be actual
  3. Therefore, a potential must be actual

Bavar might argue that this conclusion escapes contradiction insofar as the way in which a potential is actual is distinct from the way in which it is potential or unactualized. It is actual insofar as it actually exists and is actually a capacity; but it is potential/unactualized with respect to being a capacity for something.

Let’s assume for now that there is indeed no strict logical contradiction in the conclusion. There are still other serious problems with the argument which need to be addressed. For one thing, it seems that the second premise begs the question, at least implicitly, against the Thomistic position. For the Thomist wants to insist that what is real is not simply identifiable with what is actual; that the real cannot be conflated merely to the actual. Instead, the real must consist of both the actual and the potential. So the Thomist will agree that a potential must be real, but denies that this means it must therefore be actual.

A significant part of the problem seems to arise from treating a potential as a thing in itself, an object, a “what”. But this is a misunderstanding of what the Thomist means by a potential. A potential is not a thing in its own right, or even a thing at all. It is not a being, and has no being of it own. Rather, it is a principle of being, a fundamental constituent of being. Act, too, is a principle of being; and act and potency are distinct and correlative. They must be distinct principles, in order to account for the reality of change. To understand why, let us offer a definition of these principles from Klubertanz:

“In every order, act is that by which a being is or is some kind of thing or exists according to some modification . . . [and] potency is that by which a thing can be or can be some kind of a thing or can exist according to some modification” [5].

We might also say that act is the principle by which being is determined to some specific perfection; while potency is the principle by which being is undetermined but determinable to some specific perfection. So, in the example of a cup of hot tea, act is the principle by which the tea is hot; and potency is the principle by which the tea is capable of being cold, even though at the present moment it is not cold. If we do not admit that there is some aspect of the being of the tea that is presently undetermined but determinable, then we cannot explain the reality of change when the tea cools down. If the tea is completely determined already in every respect, and is in no way further determinable, then it could never change at all.

The problem with saying that a potential is something actual, then, is that it makes the potential something determined. But since a potential is by definition essentially undetermined, we have this contradiction on our hands: that a potential is now determined undetermined-ness. It becomes both determined and undetermined. This results insofar as saying that a potential, as a capacity, is something actual, something which actually exists, means that we must say that it is determined to some kind of actual existence, namely the kind of existence which is a capacity. Here a “capacity” is being treated as something positive in its own right, as a kind of perfection; but this is contrary to the very nature of what a capacity is.

Now, again, Bavar might escape the pain of strict logical contradiction by contending that a capacity is determined and undetermined in different respects. This reply itself, however, is problematic for a number of reasons. For if contradiction is truly to be avoided, the different respects in which the capacity is determined and undetermined must be really distinct, which means that necessarily the capacity must consist of at least two really distinct principles: that whereby it is determined, and that whereby it is undetermined but determinable. But these are just the principles of act and potency, as we have seen. So the capacity as understood here must really itself be composed of act and potency. But then, on Bavar’s view, we must also say that this further potency is also something actual, and hence also determined and undetermined in two different respects, and hence also composed of two distinct principles of act and potency. And this will continue for each further stage ad infinitum.

The above should serve to show, by way of a kind of reductio, that potential cannot be actual. This still leaves the important question, though, of how a potential can be real if it is not actual? This is problematic only if we think of a potential as a thing in itself, a being, rather than as a principle of being. A potential is only real insofar as it is had or possessed by something. The being belongs, not to the potential itself, but only to that thing which has the potential. The potential coldness of hot tea is not itself actual, but it belongs to something actual, namely the tea. The tea has the potential for coldness. This is how it can be the case that potentials are real without being actual in themselves.

Every individaul substance has its own act of existing which gives being to the whole. An act of existing actualizes an essence, which considered in itself would just be the potential to exist in a certain way (e.g., the essence of a dog, considered in itself, is the potential to exist as a dog). But because of the finite nature of creatures, an act of existing never actualizes the full range of potentials inherent within a given essence. The essence of tea has the potential to be either hot or cold, but never hot and cold at the same time. So the essence is given existence by the act of existing and becomes a thing, a substance; but the essence of the substance is never fully or completely actualized at once. A potential is real, therefore, not because it has its own act of existing, or its own actual existence, but because it belongs to something which does have an act of existing, as part of its essence which is currently unactualized.

Some of what I have said above is treated in Bavar’s blog post. In particular, Bavar gives a critique of the idea that act and potency are “parts” of a thing. I plan to interact with this critique in a future post. For now, I hope the above helps shed light on the Thomistic position, in addition to providing positive reason for thinking it is incorrect to say that a potential is something actual.


Special thanks to Dwight Stanislaw, a fellow Thomist, for help with thinking through some of these matters.

[1]. Feser. Five Proofs of the Existence of God. Quoted in the description of Bavar’s video, found here: https://www.youtube.com/watch?v=L5vIbFs_ICY

[2]. Su’s response, linked to in Bavar’s post, can be found here: https://docs.google.com/document/d/1NxzscuNzHsoktKsL70Dkq7S9h7nyX_hKvu-ZGocFl_Q/edit

[3]. Bavar’s reply: https://docs.google.com/document/d/1e4kCKjEG5hqT87j1E25avqlUVZ3Tnlxd3YRwQFAFJOU/edit

[4]. Su’s response: https://docs.google.com/document/d/115N_q2LaJrD4A9BpfqH3qb6CYsKj2X7LRhOV–w69HU/edit

[5]. Klubertanz, Introduction to the Philosophy of Being, second edition, Wipf and Stock Publishers, 2005, page 129.

5 thoughts on “A Response to Ben Bavar on Act and Potency, Part 1

  1. Very good, clear analysis, Harrison. One of the things that helped jump-start me at understanding this is imagining, say, Harrison in Dallas. Your being in Dallas is your locational act, while you are in potency for Boston (or anyplace else). Harrison in Boston doesn’t exist, so Harrison in Boston cannot raise himself to act. Harrison in Dallas (or wherever) must actualize Harrison in Boston. It’s simply a variation of the self-causation-is-impossible argument.

    Liked by 1 person

  2. Harrison, I asked a question about Aquinas’ Third Way under an older thread in one of you previous websites. I don’t know if you’re still getting alerts to replies under old threads, so in case you’re not, would you mind my posting the question here? If not, then where do you recommend I post it?


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