Second Response to A Tippling Philosopher on Act and Potency

Jonathan MS Pearce of the “A Tipppling Philosopher” blog has written a reply to my response to his critique of the Thomistic understanding of act and potency. Recall that his original critique, in essence, stipulated that causal determinism undermines the actus/potentia thesis:

“My main point in the piece was to undercut the differentiation that Thomists have between actuality and potentiality, such that something (X) could be potentially A or B; I say, under causal determinism (adequate or otherwise), X will only ever be A, and so there is no potential (in reality) to be B. The only thing that allows for that potentiality is from human theorising given an incomplete knowledge of all of the variables” [1].

My response was effectively that this objection, even if correct, doesn’t really undermine the Thomistic position. All it would show is that X only has the potentia for A; not that it has no potentia at all, or that potentia is not real. Even on a deterministic view, we still must posit intrinsic potentia in things to account for the reality of change. But, even further, determinism actually does not necessarily entail that X only has the potentia for A, and lacks the potentia for B. It could just mean that whatever it is which actualizes the potentia for A, is determined to actualize only that potentia, and no other. This leaves open the possibility that X as a whole has real potentiae for multiple different outcomes, but that none of them are ever actualized.

Here is what Pearce has to say in reply:

“Here, to me, we have the ungrounded assertion, in my opinion, of any kind of meaningful account, ontologically, of “intrinsic potentia”. It sounds lovely, but it is, to me, a mere assertion that this object, a coin, has some real, ontic property attached to it of turning up heads in causal circumstance (CC) Y. Somewhere, in some realm, this particular coin has the property of H in Y. And if it is subsequently flipped again, it has T(ails) in Z. And it also has the same potential to be at a 1-degree slant on the horizontal plane. Indeed, I can name any potential (possibly infinite) property it will have in the future and this will be its intrinsic potential. All that this means, however, is that “intrinsic potential” just means “future property”. “I have the power to do this” becomes “I will inexorably do this”.

Meh. With all due respect.

I’m not sure this contains any real usefulness, certainly in terms of the Thomistic framework. It’s potential is its future, which is necessarily so” [2].

Pearce calls the claim that objects have real, intrinsic potentiae a “mere” and “ungrounded assertion.” On the contrary, there is a vast tradition of argumentation for this very fact stretching back over two thousand years to Aristotle. As I said in my previous post, without the real distinction between actus and potentia, there is simply no way to account for the reality of change; and there are very strong arguments to establish this. In that post I was more concerned with responding to a critique of the actus/potentia distinction, than providing a positive case for it; but if one is interested, I have argued for it elsewhere on my blog. (See, for instance, my post on the first Thomistic thesis, which is entirely concerned with this exact issue).

Pearce next suggests that, on the Thomistic account, a real potentia simply reduces to a “future property,” such that saying “I have the power to do X” just means “I will inexorably do X.” But this is not the case. A real, intrinsic potentia is not equivalent to a future property; it is the power or possibility or capability of that future property. It obviously cannot be identical with that future property, for the future property does not yet actually exists. It exists only potentially, in the capacity of the potentia to become that property. The property and the potentia are really distinct, and have to be to make sense of real change. This is the Thomist’s whole point. Whether “there is a potentia for X” means “inexorably X will happen” depends firstly upon whether or not one is a determinist. But, as I explained above, it is not necessarily the case even on a deterministic account that some object can only have the one potentia for its inevitable outcome. So having a potentia for X does not necessarily refer to what definitley will happen; it could just refer to what can happen, relative to the nature of the thing in question. In other words, the necessity of the deterministic account could arise from the extrinsic efficient cause which determines a thing to a single outcome and hence to the actualization of a single potentia; and does not necessarily have to arise from the nature of the thing itself which has the potentia.

Either way, it is simply not the case that this understanding of actus and potentia is trivial, as Pearce seems to imply by stating that “I’m not sure this contains any real usefulness, certainly in terms of the Thomistic framework.” The truth of the matter is far to the contrary: the actus/potentia distinction does a whole lot of heavy lifting and interesting and significant metaphysical work in the Thomistic philosophical and theological system. As I wrote in another post on the subject:

“As a metaphysical theory it is extremely fruitful and has an extraordinary degree of explanatory power. It provides an important step in one of Saint Thomas’ central arguments for the existence of God; it helps Saint Thomas develop compelling answers for the philosophical issues of universals, concrete-particulars, persistence and identity through time, causation, and a host of others. In short, the act-potency distinction provides the fundamental framework from which Saint Thomas approaches pretty much every subject. It is central in his philosophy of human nature, his understanding of knowledge, ethics, and even theology and Scriptural interpretation” [3].

And this is all in addition to the thesis’s primary role of explaining the reality of change.

Next, Pearce analyzes my claim that “necessity entails possibility.” In retrospect, I don’t think I should have made this statement, as it merely complicates things and distracts from the central issues. The main point was just to reiterate what I have been saying: causal determinism does not remove the need for a real distinction between actus and potentia. Perhaps a better way to state my point would be: in an ontological sense, the fact that something must happen presupposes that it can happen, i.e. that it is not impossible for it to happen, and that there is a real capacity or ability for it to happen. If this particular acorn must become an oak tree, then this particular acorn must have the capacity or ability to become an oak tree. If it does not have such a capacity or ability, then it could not possibly become an oak tree; and its becoming an oak tree could hardly be necessary. And this capacity/ability is precisely what is meant by potentia. Positing the reality of potentia is an explanatory hypothesis, meant to account for why and how it is possible for the acorn to become an oak tree, or for any change in general to occur. Asserting that the acorn can become an oak tree because it is causally determined to do so is not a sufficient explanation, since it does not make intelligible — or really even address — how the acorn can become an oak tree in the first place, whether causally determined or not. Indeed, in this sense causal determinism is not in any way a competing or rival hypothesis to the actus/potentia distinction, insofar as they are simply concerned with entirely different questions. (It’s also important to note that appealing to a specific scientific explanation for how an acorn becomes an oak tree also does not compete with the actus/potentia account, since the latter is a metaphysical account of how change in general can occur).

So that was my intention in stating that “necessity entails possibility.” But Pearce has misunderstood this. He writes:

“Jennings would be synonymising “possible” with “necessary”, such that to say something has a potential to be something (heads or tails) means the same as to say it is necessarily heads, because its potential is necessarily heads. You are stripping modal language of its modality” [4].

Here I would just point out that the statement “necessity entails possibility” is not equivalent to “possibility entails necessity.” The two are logically distinct. The former is not equivalent to the identity of necessity and possibility. In other words, even if it is the case that necessity entails possibility, it does not follow that every instance of something being possible entails that it is also necessary. But, as I mentioned above, I no longer wish to say that necessity entails possibility in a universal sense; but only in the limited, ontological sense which I have just explained.

Pearce continues:

Jennings states, “If something must be the case, then necessarily it also can be the case” but I don’t buy this. You would never say of anything “X can be Y” and strip X of all other possibilities. Bob can be funny means that very often, or at least some of the time, he is not funny. It doesn’t mean that he is funny literally every moment of his life bar none. And reversing this, as Jennings looks to do, is merely meaningless. If Bob is literally funny every single moment of his life, then to say he can be funny is to equivocate on, or more accurately misuse, the word “can” in its modal form.

To say 2+2=4 is not to say 2+2 can equal 4 (given regular maths understanding). It means it does equal 4. Always. And forever. It doesn’t have “an ability” to, but “an ability” not to; it means it necessarily is or does” [5].

Here Pearce seems to take issue with my claim that causal determinism does not get rid of the need of positing real potentia since, at most, causal determinism would just imply that a thing only has the potentia for a single outcome, namely the one to which it is determined. As I’ve discussed above, this is not the only option when it comes to causal determinism. But even if it were, Pearce’s comments do not effectively undermine it.

Pearce’s response seems to be that we do not normally use the language of “can” in reference either to something which already is the case, or in reference to something which could not possibly be otherwise. Here we seem to be slipping into an issue of mere semantics which miss the deeper, underlying metaphysical points. The statement “Bob can be funny,” in English, does indeed seem to imply that sometimes Bob might be funny, while sometimes he is not. But even if Bob is funny at literally every single moment of his life, this is only because Bob has the real power or ability to be funny, which he is actualizing at every single moment. And, for the Thomist, “potentia” refers precisely to this real power/ability which Bob has to be funny. If Bob does not have a power/ability to be funny, he never could or would be funny in the first place.

I agree that, most of the time, when we speak of something being possible, when we use the language of “can”, we also thereby imply that it is possible that it not be; we at least implicitly indicate the reality of multiple possibilities, and not just one. If anything, this usual mode of understanding points to the falsity of causal determinism. But, if causal determinism does turn out to be correct, as Pearce thinks, then all that this means is that our normal mode of speaking/understanding does not adequatley reflect the underlying metaphysical reality. In other words, on this account, even though we imply by our speech that there are multiple possibilities, in reality there is only the one. But, again, nothing about this gets rid of the need for positing a distinction between actus and potentia.

Finally, Pearce points to various models of contemporary physics which see the universe as a 4D block universe:

It becomes even more interesting when you look at the universe in terms of how most modern physicists do: as a 4-dimensional block universe. Jennings’ use of potential requires, it seems, an A-Theory understanding of time, in a linear past (gone), present (fact), future (yet to be [potential?]). These days, however, most philosophers and scientists do not adhere to the A-Theory of time – indeed, only 15.5% of philosophers do, correlating unsurprisingly with the proportion who are theistic, give or take. On the other hand, when harmonising special and general relativity, in a block universe, the whole thing is factual. There is no potential. There just is . . . . In other words, to uphold Thomism, the Thomist has to disprove or counter the block universe (theory), and of course there are detractors, it’s just that I never see Thomists getting involved here. I could be wrong” [6].

This is somewhat correct, and somewhat incorrect. It is true, as I’ve said, that the actus/potentia distinction was originally formulated as a way to explain the reality of change; and the understanding of change which prompted the distinction, and which is most compatible with our normal experience of the world, is best described by the A-Theory of time, and specifically the version of A-Theory known as presentism. However, it is incorrect that the actus/potentia distinction necessarily requires adherence to presentism specifically or A-Theory generally. For, even though the distinction originated as a way to explain change, it has since come to be used to explain a host of other phenomena as well. (And, indeed, its fruitfullness and reach are just further evidences of its truth). For instance, the actus/potentia distinction is also extremely useful (and indeed even necessary) in explaining the infamous problem of “the one and the many.” Since this problem (and others) exists even if 4D-block-universe models are correct, and even if A-Theory is false, the actus/potentia theory in its essence remains intact, and cannot be so easily jetissoned. As Edward Feser writes in his recent book Aristotle’s Revenge:

“At least the most general concepts of Aristotelian philosophy of nature could in principle be reconciled to some extent with any of these theories [of time]. This is true even of the B-theory, though the fit is hardly comfortable” [7].

So, in fact, the Thomist does not have to disprove or counter the block universe theory. On the other hand, doing so is certainly a live option for him. Edward Feser, whom I just quoted, has just written a comprehensive case for why contemporary natural science does not undermine but indeed supports and even depends upon the reality of the Aristotelian and Thomistic metaphysical framework. In that work he defends presentism in depth. As such, I simply refer the reader to his book Aristotle’s Revenge if one is interested in further considering this issue.

Finally, Pearce concludes with this:

“If all things (given causal determinism, of course, that they would anyway reject) – including brain states and thus resulting behaviours – have “intrinsic potentiae”, then where does this get the Thomist? If we are denying alternative potentiae in saying that all things have actuality and the future actuality is necessarily dependent on previous actualities, then surely the whole Thomistic framework, as an endeavour of moral philosophy, is rendered impotent?” [8].

In other words, if the Thomist were to “bite the bullet” on the issue of causal determinism, and subscribe to the position I have outlined above, to the effect that causal determinism means agents have only the one intrinsic potentia for their single determined outcome, does this not mean that “the whole Thomistic framework, as an endeavour of moral philosophy, is rendered impotent”?

A few comments are in order here. First, the Thomistic framework is not primarily an “endeavour of moral philosophy.” Moral philosophy is simply one branch of philosophy in general, and it is far from even being the most basic or fundamental branch. So even if the above position were to “render impotent” Thomistic moral philosophy as traditionally understood, it would hardly thereby undermine Thomistic philosophy as a whole — especially not its central principles. For one thing, it would in no way undermine the traditional Thomistic proofs of the existence of God.

The next thing is to ask, how exactly does the above account actually “render impotent” the Thomistic account of moral philosophy? Presumably the assumption is that causal determinism undermines freedom of will, which is a prerequisite for moral obligation and duty. But even if this is the case, there could still in theory be certain uses for moral philosophy, especially for a system such as St. Thomas’s. For instance, even if there were no freedom of the will and hence no possibility of acting otherwise than we are determined to, it could still be the case that certain actions are objectively good/bad for us as human beings, just as there are certain foods which are objectively healthy/unhealthy for us to eat; and knowing this could still prove useful.


[1]. Pearce. “Act & Potency: Responding to a Critic.”

[2]. Ibid.


[4]. Pearce. Act and Potency.

[5]. Ibid.

[6]. Ibid.

[7]. Edward Feser. Aristotle’s Revenge: The Metaphysical Foundations of Physical and Biological Science. Editiones Scholasticae, 2019. Page 238.

[8]. Pearce.

One thought on “Second Response to A Tippling Philosopher on Act and Potency

  1. Man alive, Harrison. It looks like you’re arguing with a fella who denies that he has two eyes. He put his foot in his mouth the first time around, and now he’s managed to thrust his other one in at the same time.

    Liked by 2 people

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