This is part two of my follow-up to my original post on potentiality and inertia, where I respond to comments made by defenders of existential inertia. In the previous post we delved deeper into the nature of potentials, and saw that not everything we call a potential is equally deserving of the name. This helped us clarify the indifference of potentials, and how they relate to their actualizations. In my estimation, the indifference of potentials is the core reason for thinking that potentials depend on some other actuality for their continued actualization. In the course of this post, we will have an opportunity to further unpack these two ideas and the connection between them.

The objection of interest for this post is raised both by Joe Schmid and Graham Oppy in different contexts. Oppy, in responding to a paper by Feser, says the following:

Yesterday, throughout the entire day, there was a red chair in my room. Pick some time t around noon yesterday. At t, the chair existed, and the chair was red. Moreover, at t, the chair had the potential to exist, and to be red, at t + ε, where ε is some relatively short time interval (say, a millionth of second). Do we need to postulate the existence of some distinct thing that exists through (t, t + ε) that actualizes at t + ε the potential that the chair had at t to both exist and be red at t + ε? I do not think so. Given that, at t, the chair has the potential to exist and to be red at t + ε, all that is required for the realization of this potential is that nothing intervenes to bring it about, either that the chair does not exist, or that the chair is not red, at t + ε. Potentials to remain unchanged do not require distinct actualizers; all they require is the absence of any preventers of the actualization of those potentials. In particular, things that have the potential to go on existing go on existing unless there are preventers — internal or external — that cause those things to cease to exist.¹

In private correspondence, Schmid has raised a similar objection: even if we grant the continued indifference of potentials, all we need is some kind of explanation, not necessarily an explanation in terms of a concurrent sustaining efficient cause. The persistence in actuality could be explained by a whole host of explanatory factors that don’t invoke sustaining causes — for example, the prior state and existence of the object combined with no sufficiently destructive causal factors, or in terms of an existential inertia tendency, or something else.

It may come as a surprise, but for the most part I am in agreement with Oppy and Schmid: it is often the case that something with an actualized potential P does not require some external sustaining cause to sustain the actualization of P. As I mentioned in my original post, Newtonian inertia is a great example of this: physical objects remain maintain their rectilinear motion until some other thing causes them to stop. And the example of the chair’s “inertial color” given by Oppy is another good example: the chair maintains its color until something causes it to be another color. The trouble is that these examples don’t undermine a more nuanced rejection of existential inertia.

In my original post, we saw that the indifference of potentials is consistent with inertial behavior because of what we termed “inertial actualities”. There we arrived at these in a fairly roundabout way, but we can get to them more directly as follows. Say we have some S with potential P and its actualization A at time t, and we want an account of how A persists until some later time t+ε. Given that potentials are indifferent to their actualizations, it can’t be that P keeps A around. Of course, the continued existence of P is necessary for the continued existence of A, but its indifference to A makes it insufficient for the task. There must be something else in the picture, that isn’t indifferent to the continued actualization of P. At this point, a proponent of existential inertia might note that this could be an intrinsic aspect of S to maintain A in the absence of contrary causes. And it certainly could be, but we can know more about it. Since it’s not indifferent to A, it cannot be another potential. And since being is divided into potentiality and actuality, it must therefore be an actuality. Moreover, this actuality must be closely connected to P in a way that other actualities in S are not. This is what I call an “inertial actuality” since it’s an actuality that explains the inertial behavior of the actualization of P.

Going further, I have suggested that we understand an inertial actuality as an incomplete determination to some behavior, in such a way that it allows for variation in the details of how that behavior plays out.² This incomplete determination gives us potentials for the actuality to express itself in concrete ways. The example of interest in my original post was Newtonian inertia: by virtue of something existing as a physical thing it is determined to continue its rectilinear motion (behavior) but does not fix the vector of that motion (incomplete). Let’s say we’re considering the potential some S has to be moving along some vector V. This potential arises from the incomplete determination of S to continued rectilinear motion, but is (as all real potentials are) indifferent as to whether S is actually moving along the relevant vector. However, when the potential is actualized in S, by virtue of the underlying inertial actuality S will continue along V until stopped by something else. This isn’t because P has somehow stopped being indifferent to its actualization, but because P exists in virtue of an underlying inertial actuality that was never indifferent to S’s motion. Similarly, the material constitution of a typical chair entails that it will have some color, but is consistent with this color being one among a wide range of options. Again, this incomplete determination gives rise to a variety of potentials, each of which is indifferent to whether it is actualized. But when one is actualized, the material constitution of the chair (not the potential) ensures that it will remain actualized in the absence of contrary causes.

Thus, the inertial behavior we observe in the world points us to the lower-level inertial actuality that gives some potentials existence and maintains their actualizations in the absence of contrary causes. The relationship between the two isn’t ad hoc, either, for it is the incomplete determination to the relevant behavior that gives rise to the potentials in the first place. Furthermore, such incomplete determinations have long been recognized when thinking about change, apart from questions of existential inertia.³

All of this helps us see that Oppy’s “potential to remain unchanged” is just another example of a pseudo-potential, this time made up of the potential and the inertial actuality from whence it arises. And it also helps us see the truth of the point made by both Schmid and Oppy, that the indifference of potentials doesn’t necessitate some external sustaining cause outside of the thing with the potential, for the inertial actuality is neither external nor an efficient cause.

Where does this leave us on the question of existential inertia? I think there are two things we can say here.

First, we are still left in need of external causes for actualized potentials that can’t be sustained by some lower-level inertial actuality. Aristotelians have traditionally recognized the distinction between prime matter and substantial form, and Thomists have recognized the real distinction between essence and existence.⁴ Now, both prime matter and essence are potentials that have no lower-level actualities, and therefore there can be no inertial actuality to maintain their actualizations. In these cases, then, we would need some external cause to sustain the actualizations of these potentials.

Second, we can shift the question of existential inertia from substances to their potentials and actualities, and thereby render moot the question of external efficient causes. The question of existential inertia typically arises in the context certain arguments for God’s existence, such as Aquinas’s argument in On Being and Essence⁵ and his second way.⁶ These formulations frame the argument in terms of efficient causes of existence, but strictly speaking all we need is the actualization of potentials by other actualities. That is, we can start with some actuality and build an essentially ordered series of actualizers leading back to a pure actuality. The question of whether this requires a separate substance from the one we started with can be settled as a corollary of what it means to be pure actuality. Despite sounding similar to Aquinas’s first way — which is also construed in terms of actuality and potentiality — this is in fact a different argument. The first way proceeds from the reduction of potentiality to actuality, whereas this argument proceeds from the continued actualization of potentials.

The upshot of all of this, I think, is a more nuanced understanding of existential inertia and its rejection. When we discuss the continued existence of some aspect of reality, we need to get clear on whether it can be explained by some inertial actuality within a substance or not. And if we wish to establish a separate sustaining cause of something, then we need to be clear on which potentials we’re considering within that thing, for not all require such an explanation.

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1. Graham Oppy, “On stage one of Feser’s ‘Aristotelian proof’”.↩︎
2. There we spoke about this in terms of form and matter, but for this post we will try to restrict ourselves simply to language of actuality and potential.↩︎
3. For example, they arise in the distinction between substantial and accidental forms in the course of making sense of the difference between substantial and accidental change.↩︎
4. For my previous discussions on these, see my posts on God, matter, and necessary existence and the real distinction.↩︎
5. See the bottom of page 240 here.↩︎
6. See the corpus of ST I Q2 A3.↩︎

Recent comments by defenders of existential inertia have motivated me to return to the topic of my earlier post on potentiality and inertia. In that post I proposed that a key feature of potentials is that they are indifferent to what is actually the case. This, I explained, is the core reason for thinking that the continued actualization of a potential must depend on some other actuality. In this post we will clarify this further, and in the next post we will say more about the relation of all of this to inertia.

Joe Schmid, of Majesty of Reason, has put forward the following objection to my earlier post, which we will use as a departure point:

A potential is indifferent when merely potential, but when actualized it is no longer indifferent because it has become actual. We can’t assume that it doesn’t remain in that state of actuality absent a sustaining cause. When actualized, it is determinate with respect to its actuality, and we can’t assume that that determinacy does not persist.¹

In another statement of this objection, he asks us to imagine a fence in regard to the color it is painted:

Suppose I have a fence, and the fence has the potential to receive contrary paint colors. Take its potency to be red. Now, prior to being red (the consideration applies in both temporal and ontological senses of ‘priority’), the potency to be red is certainly indifferent to what is actual… But once the actualization occurs — say, by painting the fence red — the potency no longer is indifferent to what’s actual, since it has been made actual. And we cannot just assume that, once actualized, the ‘potency’ (previously a potency) does not or cannot remain in a state of actuality (as that is the very question at issue).²

In responding to this objection, it would help to return to a distinction I mentioned in my earlier post: in everyday language we speak about both the potential for becoming F and the potential for being F, but I noted that these are two different sorts of potentials. Indeed, not only are they different but the latter is more fundamental and more truly a potential than the former.

You see, when we move from our imprecise everyday speech to the more precise notions employed in the Aristotelian account of change, we see that the “potential” for becoming F isn’t a real potential at all. Rather it is an aggregate feature, wholly reducible to (1) the real potential for being F and (2) the actuality of being not-F — or, more accurately, the actuality of being G where G is some feature incompatible with F. This second part is needed because something can’t become F if it’s already F. Since the potential for becoming F is really this aggregate feature made up of both a potential and an actuality, it would be better to call it a “pseudo-potential” for becoming F in contrast to the “pure” or “real” potential for being F. Schmid’s fence has the real potential for being red by virtue of its structure and material constitution, and this real potential together with the fact that the fence is not actually red is what constitutes the pseudo-potential to become red. When the fences’s potential for being red is actualized, it retains the real potential (because it still has the capacity for being red) but loses the pseudo-potential (because it can no longer become red).

Unfortunately, our language is even more misleading than it may first appear, since we don’t often need to make a distinction between real potentials and pseudo-potentials. For example, Schmid’s usage of “merely potential” is in keeping with typical usage, but it isn’t the same thing as a potential simpliciter. The latter is a potential considered in itself. The former indicates that there is a potential and that this potential is unactualized. In other words, despite what we might think a mere potential is the same sort of aggregate feature as the pseudo-potential we considered above. This is why, when the potential is actualized the mere potential ceases to exist and is replaced by an “actualized potential” — a pseudo-potential referring to the same potential but this time with a fact about its actualization instead. Another common way of speaking is not in terms of potentials, but in terms of the things that have the potentials, as when we say something is “potentially F” or “in potentiality with respect to F”. To the best of my knowledge, these are typically understood as meaning that the thing has the mere potential for F.³

Unlike real potentials, pseudo-potentials aren’t indifferent to what is actually the case precisely because they have facts about actualities built into them. I gestured to all of this in my first post with the example of the one-liter bottle. This has the capacity (potential) for containing one liter of water by virtue of its design. When empty this is a mere potential (potential + unactualization) because this capacity is not actually fulfilled, and the bottle has the pseudo-potential for holding a liter more than it does. When filled, the mere potential is replaced with an actualized potential (potential + actualization), and the pseudo-potential to be filled is replaced with the pseudo-potential to be emptied. However, throughout this process the bottle retains the potential for containing a liter of water, for a bottle can’t hold a liter of water if it doesn’t at that moment have the capacity for doing so.

So, real potentials are always indifferent to what is actually the case and pseudo-potentials are never indifferent to what is actually the case. Contrary to Schmid’s suggestion, I don’t think it’s possible to have a potential only sometimes be indifferent. After all, if we supposed that a potential for being F were not indifferent to being F when actualized and indifferent when unactualized, then it’s very indifference would entail that it is actually not F!

It may help if we clarify what we mean when we say a potential is indifferent to “what is actually the case”, since this is an overly-general way of phrasing it. Specifically, a potential is indifferent in regard to its actualization. It’s entirely possible for there to be other “lower level” actualities that a potential is not indifferent to. For example, a human leg is structured in a way that permits a certain freedom of movement, ranging from a straight leg to a fully bent knee. This structure is an actuality which grounds the potential to be in any of a range of different positions. Of itself, the structure of the knee does not fix the position of the knee to any particular position — it is indifferent to the position within this range. In terms of potentials, we would say that it has the potentials to be in any of these positions. Now, each of these potentials is indifferent to the actual position of the knee (ie. whether it itself is actualized or not), but none of them is indifferent to the underlying structure of the knee, since this structure is what sustains each potential in existence. So, to nuance what we’ve been saying, a potential is indifferent to its actualization, but if it arises from a lower level actuality then it is not indifferent to that actuality.

But, we may wonder, isn’t change the actualization of a potential? For sure, but not in such a way that the potential somehow becomes an actuality and ceases being a potential. If that were the case, then we would not be able to account for the permanence across change, and every instance of “change” would amount to simple replacement. When the mere potential becomes an actualized potential, what ties these two pseudo-potentials together is the underlying real potential that remains indifferent across its actualization. Without this we would have a potential one moment and an actuality another moment, but nothing to account for their unity.⁴

What, then, do we mean when we speak of the actualization of a potential? We mean that a thing’s constitution gives it the capacity for being actual in a particular way (potential), and that this capacity has been realized in that thing (actualization). It’s not as though the capacity has become its realization, but simply that the thing now exists in a way that is within the range permitted by its constitution. This, I think, is why Thomists say that a potential “composes” with its actualization rather than “becomes” it. We could perhaps put this in terms of grounding: the potential is a partial ground for its actualization, in need of additional factors that are not indifferent to the actualization, such as an efficient cause or inertial actuality. Of all the factors that ground the actualization, the potential is what provides the capacity for being actual in the relevant way — it’s the “slot” that’s “filled in” by the other factors. It’s because of this that we associate the actuality with the potential, saying that it is the actualization of that potential.

Consider two examples. First, the materials and shape of the one-liter bottle give it the capacity (potential) for containing water, which is realized when the bottle actually contains one liter of water (actualization). The capacity doesn’t “become” the containment, but grounds it along with the factors that explain why the water is actually there. And second, the way the parts of the knee are connected allows for a certain range of movement corresponding to a collection of potentials for being in various positions. One of these potential together with the actual orientation of these parts relative to one another ground the knee’s actually being in one position rather than another.

To sum up, the analysis of change requires, and concrete examples confirm, that real potentials are indifferent to their actualizations. Schmid’s objection misses the mark because, if anything, it concerns itself with pseudo-potentials rather than real potentials. And this is an understandable consequence of our language failing to distinguish between real potentials and aggregate features made up of both potentials and actualities. While it may not always be necessary to keep such a distinction in mind, it is crucial in the debate over existential inertia.

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1. This particular phrasing came from a private Facebook conversation with Joe.↩
2. This longer version of the objection appeared a while back in the Thomism Discussion Group. Emphasis original.↩
3. This is how Aristotle uses the word, for instance, when he says that, “change is the actuality of that which exists potentially, in so far as it is potentially this actuality.” (Physics 3.1 201a10-12). See my post on actualization of potentiality as such for a brief discussion of this phrase. At the time I wrote it, I hadn’t thought much about the indifference of potentials, but I don’t think anything I say there is incompatible with it.↩
4. At the level of an individual potential and its actualization, the potential acts much like matter in the hylomorphic account of change. This is no coincidence, for matter is the “seat” of the potentials inherent in a material thing. As I’ve explained before, in general matter “is a substratum that of itself is indeterminate between various alternatives, while form is the determination of that substratum to one of those alternatives”. In other words, matter is indifferent to its determination by form.↩