Potentiality and Actuality

Here I will treat what Aristotle says about potentiality and actuality in Metaphysics book Theta (IX). On this closer reading, I was initially disappointed that he did not say more about how potentiality and actuality provide the detailed basis for the “internal” teleology that is at the core of his thinking. But on further reflection, perhaps this is another case of what I have elsewhere appreciated as a kind of careful minimalism.

“[L]et us make distinctions also about potency [aka potentiality] and complete being-at-work [aka actuality], and first about potency in the sense in which it is meant most properly, although it is not the sense that is most useful for what we now want. For potency and being-at-work apply to more than just things spoken of in reference to motion. But when we have discussed them in this sense, we will make clear their other senses in the distinctions that concern being-at-work” (ch. 1, Sachs tr., p. 167).

This most elementary sense of what I prefer to guardedly call potentiality was originally developed in the Physics, in connection with the theory of what he broadly calls “motion”. Here, he will ultimately extend it to cases that do not involve motion in this sense. I tend to think of the latter cases as primary.

“[A]s many [senses of potency] as point to the same form are all certain kinds of sources… of change in some other thing or in the same thing as other. For one kind is a power of being acted upon, which is a source in the acted-upon thing itself of passive change by the action of something else or of itself as other; another is an active condition of being unaffected for the worse…. And these potencies are in turn spoken of as only acting or being acted upon, or as acting and being acted upon” (pp. 167-168).

This is a thin, elementary definition, like that of substance in the Categories, with no mention of potentiality’s important role in Aristotle’s teleology. Until recently, working mostly from memory, I had not been thinking about what he calls “sources” (something strictly broader than “causes”) at all, or about this Physics sense of potentiality that is specifically a “source” of motion.

In the Physics, motion is in fact defined in terms of elementary versions of potentiality and actuality. Aristotle says “thus the fulfillment [actuality, being-at-work] of what is potentially, as such, is motion — e.g., the fulfillment of what is alterable, as alterable, is alteration; of what is increasable and its opposite, decreasable… increase and decrease; of what can come to be and pass away, coming to be and passing away; of what can be carried along, locomotion” (book III ch. 1, Collected Works, Barnes ed., vol. 1, p. 343).

I rather like the Collected Works translators’ choice of “fulfillment” as an English alternative to “actuality” or “being-at-work”. Grounded more in what Aristotle says about energeia than in the etymology of the new Greek word he coined for it, it does nicely capture the teleological role of actuality. Translation is often not a simple affair.

The Physics definition of motion, though, is a tricky thought: the actuality of something that as such is a potentiality. This illustrates that there can be a kind of layering with respect to these terms.

“And it is clear that there is a sense in which the potency of acting and being acted upon is one (since something is potential both by means of its own potency to be acted upon and by something else’s potency to be acted upon by it), but there is a sense in which they are different” (p. 168).

The way in which these potentialities of acting and being acted upon are said to be “one” is structurally similar to what he says in On the Soul and Metaphysics book Lambda about thought and the thing thought being one. It seems like Aristotle might consider that to be one case of this.

“[A]ll the arts and productive kinds of knowledge are potencies” (ch. 2, p. 169).

This sort of case is very important to remember when considering the meanings of “potentiality” or “source of motion”. When he is speaking the most carefully, Aristotle says the art of building is the primary “source of motion” for the building of a house.

“And all potencies that include reason are capable of contrary effects, but with the irrational ones, one potency is for one effect, as something hot has a potency only for heating, while the medical art is capable of causing disease or health” (ibid).

He treats this thesis about rational potentialities producing “contrary” effects as important. The sense seems to be that because the actualization of rational potentialities involves practical judgment about what is appropriate in a given situation, the judgment can go wrong, leading to the production of the “opposite” of the intended effect. Heat and similar things can’t “go wrong” in this way,

“And it is clear that, with the potency of doing something well, the potency of merely doing or suffering it follows along, while the former does not always follow along with the latter, since the one doing something well necessarily also does it, but the one merely doing it does not necessarily also do it well” (ibid).

This is a nice incidental mention of the normative dimension involved in all practical doing, though the technical point is about what cases include what other cases.

“There are some people, such as the Megarians, who say that something is potential only when it is active, but when it is not active it is not potential…. The absurd consequences of this opinion are not difficult to see…. [T]hese assertions abolish both motion and becoming. For what is standing will always be standing and what is sitting always sitting, since it will not stand up if it is sitting” (ch. 3, p. 170).

The Megarian logicians claimed that potentiality has no reality of its own — that everything that is, is actual. This position results in paradoxes similar to those following from the claims of Parmenides about non-being and being.

“What is capable is that which would be in no way incapable if it so happened that the being-at-work of which it is said to have the potency were present” (p. 171).

This is another specification I had lost track of working mainly from memory. I’m not sure how it would apply to his example of arts and productive knowledge, which comes closest to the extensions of Aristotelian potentiality that I have suggested (to characterize recent notions of both the “space of reasons” and “structure” as belonging to potentiality).

“And the phrase being-at-work, which is designed to converge in meaning with being-at-work-staying-complete [entelechy], comes to apply to other things from belonging especially to motions” (ibid).

This seems to be an application of Aristotle’s frequent distinction between how things are “for us” and how they are “in themselves”. The appeal to motion as a basis for understanding being-at-work or actuality is an appeal to common experience. But further below, he will contrast motion with being-at-work in a fuller sense.

He goes on to make a number of logical distinctions.

“[I]t cannot be true to say that such-and-such is possible, but will not be the case” (ibid).

(When we say something will not be the case, we are also implicitly saying there is no possibility that it will be the case. Therefore, it cannot be possible, and the statement contradicts itself.)

Potentiality is a more specific notion than possibility, but it seems that whatever is potential must also be possible, and therefore the generalization about possibility applies to all cases of potentiality.

“For the false and the impossible are not the same thing; for that you are now standing is false, but not impossible” (ch. 4, p. 172).

Similarly, generalizations about impossibility also apply to the more specific notion of potentiality.

“[I]t is also clear that, if it is necessary for B to be the case when A is, it is also necessary for B to be capable of being the case when A is capable of being the case” (ibid).

If there is a relation of necessity between actual things, then logically there must be a corresponding relation of necessity between the corresponding potential things. Possibility and necessity are the two most basic modalities in modern modal logic.

“Of all potencies, since some are innate, such as the senses, while others come by habit, such as that of flute playing, and others by learning, such as the arts, some, those that are by habit and reasoning need to have previous activity, while others that are not of that kind, and apply to being acted upon, do not need it” (ch. 5, p. 172).

For Aristotle, a sense like vision is to be understood first of all as a potentiality for the complete act of actually seeing. All other details — of optics, of physiology, of the operations of imagination, of what modern people might call the consciousness of seeing — that are conditions of the complete act, are subordinate to the complete act itself as a realized end. This is a good example of how Aristotle uses teleology to organize and coordinate other sorts of explanation.

The distinction between by “habit” (hexis, or acquired disposition) and by learning does not seem to be strict. Further below, he mentions practicing in order to play the harp as a form of learning, rather than habit. I think he is speaking casually both times. One might even say that all habits are learned; at the very least, they are acquired. (This broader term related to “second nature” seems to have been particularly important for al-Farabi, who uses it in his classic neoplatonizing elaboration of the Aristotelian theory of intellect.)

“[With irrational potencies] it is necessary, whenever a thing that is active and a thing that is passive in the sense that they are potential come near each other, that the one act and the other be acted upon” (pp. 172-173).

This formulation is surprising. I don’t understand why the qualification he applies immediately below for the case of rational potentialities (“not in every situation but when things are in certain conditions”) would not also apply to irrational potentialities. The distinction between the “rational” and “irrational” cases is based on presence or absence of a dimension of desire or choice, which seems not to affect the relevance of situations and conditions.

“[B]ut with [rational potencies] this is not necessary…. It is necessary, therefore, that there be something else that is governing; by this I mean desire or choice. For whatever something chiefly desires is what it will do whenever what it is capable of is present and it approaches its passive object…. not in every situation but when things are in certain conditions” (p. 173).

“Since what concerns the kind of potency that corresponds to motion has been discussed, let us make distinctions about being-at-work, to mark out both what it is and what sort of thing it is. For that which is potential will also be clear at the same time to those who make distinctions, since we speak of the potential not only as that which is of such a nature as to move some other thing or be moved by something else, … but also in another way, and it is because we are inquiring after that other meaning that we went through this one” (ch. 6, p. 173).

He explicitly says he will not define actuality or being-at-work, but instead suggests that we infer a pattern from a series of examples. Actually, it turns out that the more abstract pattern he is thinking of includes two distinct variants.

“The other way these things are present is in activity. And what we mean to say is clear by looking directly at particular examples, nor is it necessary to look for a definition of everything, but one can see at a glance, by means of analogy, that which is as the one building is to the one who can build, and the awake to the asleep, and the one seeing to the one whose eyes are shut but who has sight, and what has been formed out of material to the material, and what is perfected to what is incomplete…. But not all things that are said to be in activity are alike, except by analogy…. For some of them are related in the manner of a motion to a potency, others in the manner of thinghood to a material” (pp. 173-174).

At the end, he is now saying that motion and substance-essence-thinghood are the two alternate kinds of actuality or being-at-work. Motion is the “imperfect” kind that is still in process of realization, and substance-essence-thinghood is the “perfect” or “complete” kind that is an entelechy.

“And since, of the actions that do have limits, none of them is itself an end, but it is among things that approach an end, (such as losing weight, for the thing that is losing weight, when it is doing so, is in motion that way, although that for the sake of which the motion takes place is not present), this is not an action, or at any rate not a complete one; but that in which the end is present is an action. For instance, one sees and is at the same time in a state of having seen, understands and is at the same time in a state of having understood, or thinks contemplatively and is at the same time in a state of having thought contemplatively, but one does not learn while one is at the same time in a state of having learned, or get well while in a state of having gotten well. One does live well at the same time one is in a state of having lived well, and one is happy at the same time one is in a state of having been happy” (p. 174).

“And it is appropriate to call the one sort of action motion, and the other being-at-work. For every motion is incomplete: losing weight, learning, walking, house-building…; but one has seen and is at the same time seeing the same thing, and is contemplating and has contemplated the same thing. And I call this sort of action a being-at-work, and that sort a motion. So that which is by way of being-at-work, both what it is and of what sort, let it be evident to us from these examples” (pp. 174-175).

Motion and being-at-work are both said to be forms of “action”. Anything broad enough to comprehend both of these will not fit common connotations of the English word “action”, so we need to recognize that it is being used in a special sense closer to “activity”, which seems better suited to something that includes both.

“Now when each thing is in potency and when not must be distinguished, since it is not the case at just any time whatever…. Then it would be just as not everything can be healed, by either medical skill or chance, but there is something that is potential, and this is what is healthy in potency” (ch. 7, p. 175).

The reference to time does not seem to be essential. What seems decisive for these distinctions are the possibly blocking circumstances or “conditions” mentioned earlier.

“And since the various ways in which something is said to take precedence have been distinguished, it is clear that being-at-work takes precedence over potency. And I mean that it takes precedence not only over potency as defined, … but over every source of motion or rest in general. For nature too is in the same general class as potency, since it is a source of motion, though not in something else but in a thing itself as itself” (ch. 8, p. 177).

This is the first of several iterations on the precedence of actuality or being-at-work over potentiality. The way that he respectively defines potentiality and nature as sources of motion, they are strict logical complements of one another, so he is implying that all sources of motion are either natures or potentialities.

“And this is why it seems to be impossible to be a house-builder if one has not built any houses, or a harpist if one has not played the harp at all; for the one learning to play the harp learns to play the harp by playing the harp, and similarly with others who learn things…. But since something of what comes into being has always already come into being, and in general something of what is in motion has always already been moved…, presumably the one who is learning must also already have something of knowledge” (p. 178).

Aristotle’s account of the precedence of actuality over potentiality might be the origin of the “always already” theme. This is also the root of many interesting things that Hegel says about Wirklichkeit (commonly translated as “actuality”, with Aristotle in mind).

“But surely [being-at-work] takes precedence in thinghood too, first because things that are later in coming into being take precedence in form and in thinghood (as a man does over a boy, or a human being over the germinal fluid, since the one already has the form, and the other does not), and also because everything that comes into being goes up to a source and an end (since that for the sake of which something is is a source, and coming to be is for the sake of an end), but the being-at-work is an end, and it is for the enjoyment of this that the potency is taken on. For it is not in order to have the power of sight that animals see, but they have sight in order to see, and similarly too, people have the house-building power in order that they may build houses, and the contemplative power in order that they may contemplate; but they do not contemplate in order that they may have the contemplative power, unless they are practicing, and these people are not contemplating other than in a qualified sense, or else they would have no need to be practicing contemplating” (ibid).

Here he implicitly mentions the teleological aspect, referring to ends and that-for-the-sake-of-which.

Sachs aptly comments, “How does nature display that a squirrel has reached the completion for the sake of which it exists? In the spectacle of the squirrel at work being a squirrel…. Aristotle is arguing that the very thinghood of a thing is not what may be hidden inside of it, but a definite way of being unceasingly at-work, that makes it a thing at all and the kind of thing it is” (p. 179n).

(I would say “is what it is” instead of “exists” in the part about the squirrel.) The other part, that thinghood is not hidden inside things, but rather manifest in their ways of being at work, makes me think of what Hegel says about essence.

“[T]he putting to use of some things is ultimate (as seeing is in the case of sight…), but from some things something comes into being….[O]f those things from which there is something else apart from the putting-to-use that comes into being, the being-at-work is in the thing that is made…; but of those things which have no other work besides their being-at-work, the being-at-work of them is present in themselves (as seeing is in the one seeing and contemplation in the one contemplating, and life is in the soul, and hence happiness too, since it is a certain sort of life). And so it is clear that thinghood and form are being-at-work” (p. 179).

The last sentence is a principal new conclusion of book Theta: substance-essence-thinghood and form are both said to be cases of actuality or being-at-work.

Since actuality or being-at-work has already been identified with entelechy, this means that both independent things and (some) forms are now also being said to be entelechies. In the case of independent things, this is not surprising, given everything that was said about them in book Zeta. In the case of forms, I suspect he means that those forms that are souls are entelechies.

“But being-at-work takes precedence in an even more governing way; for everlasting things take precedence in thinghood over destructible ones, and nothing that is in potency is everlasting…. Therefore nothing that is simply indestructible is simply in potency (though nothing prevents it from being potentially in some particular respect, such as of a certain sort or at a certain place), and so all of them are at work. And none of the things that are by necessity is in potency (and yet these are primary, since if they were not, nothing would be), nor is motion, if there is any everlasting one; … and this is why the sun and moon and the whole heaven are always at work” (p. 180).

Aristotle generously calls everything “everlasting” that is apparently so, and for which he has no evidence to the contrary.

“And things that undergo change, such as earth and fire, mimic the indestructible things, since they too are always at work, for they have motion in virtue of themselves and in themselves” (p. 181).

What Aristotle calls matter is not itself alive, but nonetheless he says it has intrinsic motion. Motion, as we saw above, is defined in implicitly teleological terms in the Physics, using both potentiality and actuality. This is how the behavior of inanimate matter for Aristotle ends up having teleological characteristics.

“And that being-at-work is a better and more honorable thing than a potency for something worth choosing, is clear from these considerations. For whatever is spoken of as being potential is itself capable of opposite effects…. And in the case of bad things, it is necessary that the completion and being-at-work be worse than the potency…. Therefore it is clear that there is nothing bad apart from particular things, since the bad is by nature secondary to potency. Therefore among things that are from the beginning and are everlasting, there is nothing bad, erring, or corruptible” (ch. 9, pp. 181-182).

Things that don’t measure up to what they are supposed to be are “bad” examples of the kind of things that they are. I am surprised that he speaks of any “completion and being-at-work” of bad things at all.

“And geometrical constructions are discovered by means of activity, since it is by dividing up the figures that people discover them…. And so it is clear that the things that are in the figures in potency are discovered by being drawn into activity, … and for this reason it is only those who make a construction who know it” (p. 182).

Aristotle seems to anticipate the attitude of mathematical constructivism.

“[B]ut the most governing sense [of being and not being] is the true or the false…. For it is necessary to examine in what way we mean this. For you are not pale because we think truly that you are pale, but rather it is because you are pale that we who say so speak the truth” (ch. 10, p. 183).

I was a bit surprised when he earlier ruled out further discussion of being in the sense of the true and false attributed to the “is” or “is not” used to form propositions. But here, he goes on to speak of a different notion of truth, which seems to be more like metaphorically “grasping” an essence.

“But now for things that are not compound, what is being or not being, and the true and the false? For the thing is not a compound, so that it would be when it is combined and not be if it is separated, like the white on a block of wood or the incommensurability of the diagonal; and the true and false will not still be present in a way similar to those things. Rather, just as the true is not the same thing for these things, so too being is not the same for them, but the true or false is this: touching and affirming something uncompounded is the true (for affirming is not the same thing as asserting a predication), while not touching is being ignorant (for it is not possible to be deceived about what it is, except incidentally). And it is similar with independent things that are not compound, since it is not possible to be deceived about them; and they are all at work, not in potency, for otherwise they would be coming into being and passing away, but the very thing that is does not come to be or pass away, since it would have to come from something. So it is not possible to be deceived about anything the very being of which is being-at-work, but one either grasps it or does not grasp it in contemplative thinking; about them, inquiring after what they are is asking whether they are of certain kinds or not” (p. 184).

What is meant to be included under “independent things that are not compound” and “anything the very being of which is being-at-work” — about both of which it is said to be impossible to be deceived — has yet to be specified.

The “grasping” and “touching” metaphors here need not be taken as literally implying a kind of immediate experiencing. The next book will be explore at length the ways in which things are one, and thus form wholes. I think the implicit emphasis here is on a grasping of things as integral wholes. When we think of an essence as an integral whole, either we get it or we don’t, just as he says here. How we are able to do this is another question, not addressed here, but I think that for rational animals, the immediacy of grasping an essence can only be what Hegel would call a “mediated” immediacy.

“The true is the contemplative knowing of these things, and there is no falsity, nor deception, only ignorance, and not the same sort of thing as blindness; for blindness would be as if someone were not to have the contemplative power at all” (ibid).

Form, Substance

Faced with questions like what the world is “made of”, modern people have generally assumed that it must be some kind of “stuff”. The usual presumed answer is some sort of matter-stuff, or less commonly some sort of mind-stuff.

Plato and Aristotle already suggested a radical alternative to this way of thinking that takes the accent away from “stuff” altogether. Aristotle especially developed a rich account of how we think about these kinds of things, by looking at how we express these kinds of questions, and what we are implicitly trying to get at when we ask them.

The most obvious simple answer attributed to Plato and Aristotle is form. In Aristotle’s case, one should also mention what has been traditionally called substance.

Etymologically, eidos — the Greek word we translate as “form” — seems to begin from a notion of visual appearance, with an emphasis on shape. It acquired a more abstract sense related to geometrical figure. Plato attributed great significance to the practice of geometry as an especially clear and perspicuous kind of reasoning, but he also recognized a broader kind of reasoning associated with a dialectic of question and answer, which comes into play especially where questions of value are concerned. From a point of view of ethical practice and human life generally, questions about what something really is and why this rather than that are more important than what things are made of (see What and Why). Already with Plato, “form” came to be inseparable from meaning.

Aristotle’s classic discussion of substance (ousia) in the Metaphysics starts from the idea of a substrate in which properties inhere. This most superficial level later inspired the Greek grammarians to articulate the notion of a grammatical subject of predicates. In what I think is the single greatest example of ancient dialectic, Aristotle gradually steps back from the simple notion of a substrate. Substance becomes “what it was finally to have been” a thing, at the end of the day so to speak. But then this is further interrogated to disclose the level of actuality, or what is effectively operative in a process. But it turns out that actuality is not complete in itself. What is effectively operative does not form a self-contained whole that explains everything. A fuller understanding must take into account potentiality, which leads to a transition away from simple actuality to a larger perspective of processes and degrees of actualization, in which nothing is simply given just as it is. Aristotle was especially concerned with the forms of living things, which have this character.

The more interesting senses of form for Plato and Aristotle do not refer to something that could be simply given. In line with this but in a more speculative mode, Plotinus suggested that every form somehow in a way “contains” all other forms. The poetic truth in this is that the articulation of one form depends on the articulation of other forms, and while everything in some sense coheres, we have no unconditional starting point. We always begin in the middle somewhere, in a context that has yet to be fully elaborated. The work of elaboration is itself the answer. (See also Interpretation.)

The Importance of Potentiality

I think modern philosophy generally is handicapped in its thinking about the empirical world by its lack of a notion like Aristotelian potentiality. To build context, I need to first say a bit more about the role of actuality.

The modern concept of a factual, existing world is relatively close to Aristotelian actuality, but the first big difference is that it is not paired with anything. The modern concept of a factual world is something that is supposed to be complete in itself, whereas for Aristotle, actuality in the world is always complemented by some correlative potentiality. Aristotle did not consider actuality alone to be sufficient to account for the world as we experience it.

To say that something is actually X is to judge that it has achieved and is stably continuing to achieve a full expression of what it is to be X, which means it is actively fulfilling that for the sake of which X’s do what they characteristically do (see also Entelechy). This kind of judgment is inherently normative. In thinking about it, it is important not to set the bar too high — Aristotle thinks it is true of many things. But it is not true of all existing things.

Actuality also does not exactly correspond to a state of things, but rather expresses what is effectively operative. This is semantically a bit deeper than a notion of state. At the same time, it does not have state’s strong implications of complete determination. It also does not have the monolithic unity of a state. Actuality in the world consists of many coexisting things. Further, it is not intended by itself to provide all the resources needed to account for change and what happens next. This is related to the fact that for Aristotle, the operative determination of things is not entirely univocal. (See also Equivocal Determination.)

Enter potentiality. For Aristotle, all necessity is hypothetical, dependent upon conditions. Potentiality in general occupies the space of what is not univocal in the determination of things. For Aristotle a potential X will “naturally” become an actual X if no other cause stands in the way (which is sometimes a big if; e.g., we could legitimately say that the motivated high school student is a potential doctor who would become an actual doctor given the opportunity, but she may not even have to opportunity to go to university),

But the same being or thing may be potentially many things. A block of stone may be potentially a statue of Hermes, and at the same time potentially a bowl. A devout student might at the same time potentially be a doctor, a mother, and a nun. Potentialities of the same being or thing may be either mutually exclusive (like being a statute and being a bowl, or being a mother and being a nun) or compatible (like being a mother and being a doctor).

A being or thing’s potentiality in general (as distinct from specifically being potentially this or that) corresponds to multiple concrete possibilities of realization that are already implicit in current reality, but are not necessarily all compatible with one another.

At the same time, this is a far more specific notion than mere logical possibility. Potentiality is closely dependent on whatever actualities have already been concretely achieved.

At the same time, it occupies the real gaps or holes in what is determined about the future of each thing. For each aspect of things where there is not univocal determination, there are instead multiple potential alternatives. This correlates with the fact that, for Aristotle — in contrast to Poincaré’s classic formulation of modern determinism — the present does not completely determine the future.

Poincaré famously claimed that from the state of the universe at any arbitrary point in time, its entire future is completely determined. This resembles the Stoic notion of fate, transferred to a modern event-based model of causality. For both the Stoics and Poincaré, the world is completely univocally determined. Like Aristotle, they emphasized the intelligibility of the world and of change in the world, but they made the very strong assumption of complete univocal determination. Aristotle did not.

Aristotle’s notion of intelligibility is broadly semantic and normative, whereas Poincaré’s is mathematical. With semantic and normative interpretation, there is always a question of how far we develop the account, which in principle could be extended indefinitely. It thus naturally lends itself to an account of incomplete determination, corresponding to some stopping point. Aristotle does not claim any more determination than he can show.

Poincaré’s approach, by contrast, requires that we assume there is a complete univocal determination of the world by mathematical laws, even though we can never even come close to knowing enough to show it. This assumption leaves no room for anything like potentiality.

Some philosophers have also denied the relevance of potentiality, either implicitly (like Spinoza) or explicitly (like Nietzsche).

The modern factual world is usually considered as something that just is, without modal qualification, but I have increasingly begun to doubt whether for Aristotle there is any non-modal account of the world. I read actuality and potentiality both as modal concepts, and most things in the Aristotelian world as parsable into actuality and potentiality.

What’s important about this is that potentiality is not just some mysterious “metaphysical” concept that we could maybe do without. It is a distinct logical/semantic modality supporting multiple virtual alternatives for the same thing. It allows us to intelligibly account for the incomplete determination we really experience, rather than treating real-world incompleteness and ambiguity as if it were a kind of flaw. Through its relation to actuality, it is also tied to normative evaluation. (See also Structural Causality, Choice; Values, Causality; Structure, Potentiality.)