Unit 3 | Natural Substances as Hylomorphic Compounds

3.1 | Nature & Causation

The unity of Aristotle’s Physics is a matter of scholarly controversy, but it seems clear that Physics 2–4 (at least) constitute a continuous discussion of nature (phusis). Physics 2 provides the foundation of this discussion, defending a definition of nature as well as an enumeration of the kinds of cause operative in the things that come about by or in accordance with nature.

A Division Among Beings

Physics 2.1 begins with a distinction among beings (ta onta):

Physics 2.1, 192b8–23 (RFH quasi-literal translation)

Among the things that are (ta onta), some are by nature (phusei), while others are due to other causes (aitia). By nature are animals and their parts; plants; and simple bodies like earth, fire, air, and water (for we say that these and things like them are by nature); and all of these plainly differ from those things which are not constituted by nature. For each of these [which are constituted by nature] has in itself a principle (archē) of change and rest, some [a principle of change] in respect of place, some in respect of growth and decay, and some in respect of alteration.

By contrast, a bed, or cloak, or anything else of that sort does not have an innate impulse for change, [at least] not qua satisfying these descriptions and to the extent that they are products of craft (technē). However, insofar as they are made of stone or earth, or a mixture of the two, to that extent they do [have an innate impulse for change], since nature is a kind of principle and cause of changing and resting in that to which it belongs primarily, in virtue of itself and not accidentally.

  • Here Aristotle divides ta onta (exhaustively?) into two kinds:
    • Those that are (what they are) by nature, which, as the sort of things they are, have an internal causal principle of change and rest.

    • Those that are (what they are) not by nature, which do not, as the sort of things they are, have an internal causal principle of change and rest, but come about from other causes (e.g., craft).

Nature as a Principle of Change

What distinguishes things that are by nature from things that are due to other causes (including craft) is the presence of a certain internal cause and source of change and rest, which Aristotle identifies as nature:

A causal source (principle) of change/rest internal to what it belongs to primarily in virtue of itself (per se), i.e. not accidentally.
  • The qualification in virtue of itself or non-accidentally refers to the connection between what is said to be “by nature” and what the nature in question is said to be predicated of:

Physics 2.1, 192b23–32 (RFH quasi-literal translation)

I mean by “not accidentally” that, for instance, although a doctor might be a cause of health in himself, he nevertheless has skill in medicine not to the extent that he is healed; rather, the doctor just happens to be the same as the person who is healed. Indeed, this is why the two [sc. doctor and patient] can be separated from one another. Circumstances are similar with each of the other things that have been made: none of them have the source of production in themselves. Rather, for some [the cause] is present in other things and comes from without, such as a house and other handmade products, while for others it is present in themselves but not in virtue of themselves—whatever comes to be a cause of itself accidentally.

Questions for Aristotle’s definition:

  • What’s the order of explanation between the division of beings and the definition of nature? Do we take the division as given and posit the presence of nature to explain it, or is it the other way around? (Cf. 193a3 ff.: “That there is such as thing as nature would be ludicrous to try to show…")

  • For A., nature is a “causal principle”, both an archē and a cause (aition, aitia):

    • How does nature (understood as an archē) relate to the archai of natural beings discussed in Physics 1?

Physics 2.1, 293b18–21 (RFH tr.)

Now, both form and nature are double, since privation too is in a way form. But whether or not privation and opposition of a sort are concerned with unqualified generation, we will have to inquire later.

  • How does nature operate as a cause? (Cf. Physics 2.3: cause is said in many ways…)

Nature as Form and Matter

One step toward answering these questions is to observe that, in Physics 2.1, A. identifies nature with both substance- and subjecthood.

Nature as Substance and Subject

Physics 2.1, 192b32–34 (RFH quasi-literal translation)

Nature, then, is what we said, and everything that has such as principle has a nature. All of these, moreover, are substances (ousiai), since each is a kind of subject (hupokeimenon ti), and nature is always present in a subject.

Nature as Matter

Because all nature is present in a subject, and (as we’ve seen) matter is a subject, it is only natural to suppose that the nature of each thing corresponds to its matter.

Physics 2.1, 193a9–17 (RFH rough trans.)

The nature and substance of things in which nature is present seem to be that which exists primary in each, unformed in virtue of itself, [so that] for instance wood would be the nature of a bed and bronze of a statue. As a sign of this Antiphon says that if you bury a bed and the rotting wood acquired the capacity (dunamis) to send up a shoot, what would come about would not be a bed but wood, which shows that what exists accidentally is the arrangment according to convention and craft [sc. the bed], but the substance is the other [sc. the wood], which also remains continuously and suffers these [changes in arrangement].

As A. makes clear, this line of reasoning terminates in the conclusion that the elements are the nature of things, for if wood is the nature of the bed, and wood stands (e.g.) to earth as the bed to the wood, then earth would be the nature of wood.

Physics 2.1, 193a22–28 (Charlton tr.)

Hence fire, earth, air, and water have been held to be the nature of things, some people choosing just one for this role, some several, and some making use of all. Those who fix on some such element or elements represent it or them as the entire reality, and say that other things are merely affections, states, or dispositions; and these elements are all held to be imperishable in that they do not change out of themselves, whilst other things come to be and pass away as often as you please.

Nature as Form

For A., however, nature can also refer to the form (morphē) and logos of each thing. Aristotle offers three arguments for this conclusion:

  • Analogy with the Products of Craft

    Physics 2.1, 193a28–b5 (Charlton tr.)

    That is one way of using the word “nature”: for

    1. the primary underlying matter in each case, of things which have in themselves a source of their movements and changes.

    2. It is also used for the shape and form which accords with a thing’s account.

    [Argument for 2] Just as that which is in accordance with art and artificial is called art, so that which is in accordance with nature and natural is called nature. And as in the one case we would not yet say that a thing is at all in accordance with art, or that it is [in accordance with] art, if it is a bed only in possibility, and has not yet the form of a bed, so with things constituted naturally: that which is flesh or bone only in possibility, before it acquires the form which accords with the account by which we define what flesh or bone is, does not yet have its proper nature, and is not a thing due to nature. So there is another way of speaking, according to which nature is the shape and form of things which have in themselves a source of their changes, something which is not separable except in respect of its account.

    The argument proceeds as follows:

    P1 : We use “nature” in the same way that we use “art” (or “craft”, technē)

    P2 : We say things are (what they are) in accordance with art only when they actually possess the form imposed on them by the relevant art. - Example: Wood that is potentially a bed is not yet in accordance with art; only when it actually has the form of a bed.

    C : So, by analogy, we say things are (what they are) in accordance with nature only when they actually possess “the form which accords with the account by which we define” what it is. - Example: What is potentially flesh or bone is not yet in accordance with nature [= the nature of flesh/bone?]; only when it actually has the relevant form.

  • Parity of Reasoning

    As A. suggests in the previous argument, nature is also “the shape and form of things which have in themselves a source of their changes, something which is not separable except in respect of its account” (on which see Physics 2.2). With the next argument, A. begins to make clear in what sense form can operate as a source of change.

    The argument attempts to argue by parity of reasoning with Antiphon’s bed argument earlier in the chapter:

    Physics 2.1, 193b8–12 (RFH tr.)

    Furthermore, a human comes to be from a human, but not a bed from a bed. This is also why people say the shape is not nature but rather the wood, because if it grew it would not be a bed that came to be but wood. Hence if this is nature, so too must the form be nature, since human comes from human.

  • Nature as End of Change

    In different ways, then, both nature-as-form and nature-as-matter seem to have a causal role in the origin and source of natural changes. Additionally, nature-as-form has a role to play as the end towards which a natural change proceeds:

    Physics 2.1, 193b–18 (RFH tr.)

    Furthermore, nature spoken of as coming-to-be is a path into nature (hodos eis phusis). This is not like the practice of medicine, which is said to be a path, not into medicine, but to health. The reason is that the practice of medicine must not proceed to medicine, but from it, whereas nature does not stand to nature in this way. To the contrary, what grows, qua growing, proceeds from something into something. What, then, is it that grows? It is not that from which, but rather that into which, it grows. Therefore form is nature.

    Note : “nature” (phusis) derives from the Greek word for “grow” (phuein).

    A. makes this point a bit more clearly in Physics 2.2:

    194a28–33 (RFH rough tr.)

    Nature is an end (telos) and that for the sake of which (hou heneka), for when in a continuous change there is some end, this [sc. the end] is the last and that for the sake of which. For this reason too the poet was ridiculous to say “he has reached the end for whose sake he was born”. For not everything which is last should be considered the end, but rather the best.

Nature as Cause

For A., then, nature, understood as a principle of change, is “double” (dichōs), both form and matter. The two senses, however, are not equal, since for A. form must be considered more nature than matter:

193b6–8 (RFH tr.)

This [sc. form, morphē?] is nature rather than the matter. For each thing is more property said [to be what it is] when it is actually, rather than potentially.

How is this double conception of nature reflected in A.’s idea that nature is a kind of cause? To answer this question, we need to turn to Physics 2.3, where A. outlines the different ways in which things are said to be a cause (aitios, aition):

Physics 2.3, 194b23–195a3 (Charlton tr.)

  1. According to one way of speaking, that out of which as a constituent a thing comes to be is called a cause; for example, the bronze and the silver and their genera would be the causes respectively of a statue and a loving-cup.

  2. According to another, the form or model is a cause; this is the account of what the being would be, and its genera—thus the cause of an octave is the ratio of two to one, and more generally number—and the parts which come into the account.

  3. Again, there is the primary source of the change or the staying unchanged: for example, the man who has deliberated is a cause, the father is a cause of the child, and in general that which makes something of that which is made, and that which changes something of that which is changed.

  4. And again, a thing may be a cause as the end. That is what something is for, as health might be what a walk is for. On account of what does he walk? We answer ‘To keep fit’ and think that, in saying that, we have given the cause. And anything which, the change being effected by something else, comes to be on the way to the end, as slimness, purging, drugs, and surgical instruments come to be as means to health: all these are for the end, but differ in that the former are works [or functions, erga ] and the latter tools [ organa ].

How nature-as-form and nature-as-matter map on to the notion of cause in these senses is an important question for the remainder of Physics 2. We’ll pick up with it next Thursday, and then again next week.

3.2 | Necessity & Teleology


Physics 2.1
Nature is an internal causal principle of change and rest in that which is by nature primarily and non-accidentally.
What kind of causal principle?
It’s complicated…
  • Physics 2.1–2: Nature is “double”, both formal and material.

  • Physics 2.3: “Cause” is said in many ways: formal, material, efficient, and final.

Drawing Conclusions

In Physics 2.7 A. consolidates some of these conclusions:

Physics 2.7, 198a22–31 (Hardie and Gaye tr.)

Now, the causes being four, it is the business of the student of nature to know about them all, and if he refers his problems back to all of them, he will assign the ‘why’ in the way proper to his science—the matter, the form, the mover, that for the [25] sake of which. The last three often coincide; for the what and that for the sake of which are one, while the primary source of motion is the same in species as these. For man generates man—and so too, in general, with all things which cause movement by being themselves moved; and such as are not of this kind are no longer inside the province of natural science, for they cause motion not by possessing motion or a source of motion in themselves, but being themselves incapable of [30] motion.

  • The form, mover, and that for the sake of which are, in many cases, operations of formal nature in natural substances.

  • Notice, however, that matter too can operate as a source of motion, as when we say that something is heated due to the presence of fire. In natural substances (a plant or animal, say) these sorts of efficient causes cannot directly be attributed to formal nature but rather material nature. How do these two types of cause interact in nature?

  • Answering this question is the topic of Physics 2.8–9, which Aristotle devotes to arguing for two claims:

    • Physics 2.8: That “nature belongs to the class of causes that act for the sake of something” (198b9–10)

    • Physics 2.9: The place of (material) necessity in nature, “for all writers ascribe things to this cause, arguing that since the hot and the cold and the like are of such and such a kind, therefore certain things necessarily are and come to be—and if they mention any other cause (one friendship and strife, [15] another mind), it is only to touch on it, and then good-bye to it” (198b10–15).

Nature as a Final Cause

Some things in nature do not happen for the sake of anything, even though it benefits something.
  • Even if the farmer benefits from the rain, it does not rain for the sake of making the corn grow.

  • Even if the tourism industry in Antalya benefits from sunny summer weather, the weather is not sunny for the sake of the tourism industry.

Why shouldn’t all natural processes happen this way?

Physics 2.8, 16–32 (Hardie and Gaye tr.)

A difficulty presents itself: why should not nature work, not for the sake of something, nor because it is better so, but just as the sky rains, not in order to make the corn grow, but of necessity? (What is drawn up must cool, and what has been cooled must become water and descend, the result of this being that the corn grows.) [20] Similarly if a man’s crop is spoiled on the threshing-floor, the rain did not fall for the sake of this—in order that the crop might be spoiled—but that result just followed. Why then should it not be the same with the parts in nature, e.g. that our teeth should come up of necessity—the front teeth sharp, fitted for tearing, the [25] molars broad and useful for grinding down the food—since they did not arise for this end, but it was merely a coincident result; and so with all other parts in which we suppose that there is purpose? Wherever then all the parts came about just what they would have been if they had come to be for an end, such things survived, being [30] organized spontaneously in a fitting way; whereas those which grew otherwise perished and continue to perish, as Empedocles says his ‘man-faced oxprogeny’ did.

Aristotle’s Principal Argument for Natural Teleology

Physics 2.8, 198b32–199a8

Yet it is impossible that this should be the true view. For teeth and all other natural things either invariably or for the most part come about in a given way; but of not one of the results of chance or spontaneity is this true. We do not [199a1] ascribe to chance or mere coincidence the frequency of rain in winter, but frequent rain in summer we do; nor heat in summer but only if we have it in winter. If then, it is agreed that things are either the result of coincidence or for the sake of something, and these cannot be the result of coincidence or spontaneity, it follows [5] that they must be for the sake of something; and that such things are all due to nature even the champions of the theory which is before us would agree. Therefore action for an end is present in things which come to be and are by nature.

  • A (very) rough reconstruction.

    P1 : For any product of nature, o, either o comes about by chance or o comes about for the sake of something.

    P2 : If o comes about by nature, then o comes about (in the way it does) either always or for the most part (i.e. if nothing external interferes).

    P3 : Nothing that happens always or for the most part comes about by chance.

    C : So, if o comes about by nature, then o comes about for the sake of something.

  • Supplement: Aristotle on Chance

    A. here seems to be relying on Physics 2.4–6, which argued that chance and spontaneity are distinct sorts of cause, in particular on this observation:

    Physics 2.5, 196b1–16 (Hardie and Gaye tr.)

    First then we observe that some things always come to pass in the same [10] way, and others for the most part. It is clearly of neither of these that chance, or the result of chance, is said to be the cause—neither of that which is by necessity and always, nor of that which is for the most part. But as there is a third class of events besides these two—events which all say are by chance—it is plain that there is such [15] a thing as chance and spontaneity; for we know that things of this kind are due to chance and that things due to chance are of this kind.

    Aristotle reiterates this observation in Physics 2.8 (199b16–26, Hardie and Gaye tr.)

    For those things are natural which, by a continuous movement originated from an internal principle, arrive at some end: the same end is not reached from every principle; nor any chance end, but always the tendency in each is towards the same end, if there is no impediment.

    The end and the means towards it may come about by chance. We say, for instance, that a stranger has come by chance, paid the ransom, and gone away, [20] when he does so as if he had come for that purpose, though it was not for that that he came. This is accidental, for chance is an accidental cause, as I remarked before. But when an event takes place always or for the most part, it is not accidental or by [25] chance. In natural products the sequence is invariable, if there is no impediment.

  • Questions for Aristotle’s Argument

    Might not A. be begging the question against his opponents? (More on this Thursday)

The Craft Analogy

Aristotle’s conception of natural teleology relies on an important analogy with art (or craft, technē), which in his view always operates:

  • Either to bring to completion what nature has not finished, or
  • Imitates nature.

Physics 2.8, 199a17–18

If, therefore, artificial products are for the sake of an end, so clearly are natural products.

For Aristotle’s the analogy is strict: apart from the fact that the causes of artificial products are external to the products themselves, art and nature are purposive in the same way:

Physics 2.8, 199b26–30 (Hardie and Gaye tr.)

It is absurd to suppose that purpose is not present because we do not observe the agent deliberating. Art does not deliberate. If the ship-building art were in the wood, it would produce the same results by nature. If, therefore, purpose is present in art, it is present also in nature. The best illustration is a doctor doctoring himself: [30] nature is like that.

Two Kinds of Necessity

  • In Physics 2.8, Aristotle associated form with “the cause in the sense of that for the sake of which” (199a30–33).

  • In Physics 2.9, when Aristotle turns to the role of necessity (anankē) in nature, he argues for a subordinate causal role for material nature in natural processes.

  • To do so, however, he has to clarify the sense in which it is true to say that things happen necessarily in nature. Again he relies on an analogy with craft:

Physics 2.9, 199b33–200a14 (Hardie and Gaye tr.)

The current view places what is of necessity in the process of production, just as if one were to suppose that the wall of a house [200a1] necessarily comes to be because what is heavy is naturally carried downwards and what is light to the top, so that the stones and foundations take the lowest place, with earth above because it is lighter, and wood at the top of all as being the lightest. Whereas, though the wall does not come to be without these, it is not due to these, [5] except as its material cause: it comes to be for the sake of sheltering and guarding certain things.

Similarly in all other things which involve that for the sake of which: the product cannot come to be without things which have a necessary nature, but it is not due to these (except as its material); it comes to be for an end. For instance, why is a saw such as it is? To effect so-and-so and for the sake of so-and-so. This [10] end, however, cannot be realized unless the saw is made of iron. It is, therefore, necessary for it to be of iron, if we are to have a saw and perform the operation of sawing. What is necessary then, is necessary on a hypothesis, not as an end. Necessity is in the matter, while that for the sake of which is in the definition.

It seems that we can explain a number of natural processes by focusing only on the necessary (efficient causal) effects of matter, e.g. heatings and coolings, hardenings and softenings, etc.
Doesn’t this make the role of formal nature as a final cause redundant?
No! All that happens “of necessity” in these natural processes is conditional on a hypothesis, namely: that there is to be an F.

Physics 2.9, 200a24–29 (Hardie and Gaye tr.)

If then there is to be a house, such-and-such things must be made or be there already or exist, or generally [25] the matter relative to the end, bricks and stones if it is a house. But the end is not due to these except as the matter, nor will it come to exist because of them. Yet if they do not exist at all, neither will the house, or the saw—the former in the absence of stones, the latter in the absence of iron…

Cause sine qua non (without which not).

3.3 | A Hylomorphic Model of Animal Generation

GC 2.9 | Return to the Number and Nature of the Principles of Coming-to-Be

Physics 1.7
The principles of coming to be are three - form, privation, and subject.
Physics 2.1
These principles can be consigned to matter (subject) and form (form and privation).
GC 2.9
There is a third principle “present over and above” matter and form…

GC 2.9, 335a28–32 (Joachim tr.)

The principles, then, are equal in number to, and identical in kind with, those in the sphere of the eternal and primary things. For there is one in the sense of matter, and a second in the sense of form; and, in addition, the third must be present [30] as well. For the two are not sufficient to bring things into being, any more than they are adequate to account for the primary things.

Against “Purely Material” Explanations of Generation

3 Problems:

  • Matter is passive

    GC 2.9, 335b30–34 (Joachim tr.)

    For, to begin with, it is characteristic of matter to suffer action, i.e. to be moved; but to move, i.e. to act, belongs to a different power. This is obvious both in the things that come-to-be by art and in those that come-to-be by nature. Water does not of itself produce out of itself an animal; and it is the art, not the wood, that makes a bed.

  • “Omits the more controlling cause”

    GC 2.9, 335b34–5 (Joachim tr.)

    Nor is this their only error. They make a second mistake in omitting the more controlling cause; for they eliminate the essential nature, i.e. the form.

  • Mistakes instruments used by the cause for the cause itself

    GC 2.9, 336a1–14 (Joachim tr.)

    And what is more, since they remove the formal cause, they invest the forces they assign to the simple bodies—the forces which enable these bodies to bring things into being—with too instrumental a character. For since (as they say) it is the nature of the hot to dissociate, of the cold to bring together, and of each remaining [5] contrary either to act or to suffer action, it is out of such materials and by their agency (so they maintain) that everything else comes-to-be and passes-away. Yet it is evident that even Fire is itself moved, i.e. suffers action.

    Moreover their procedure is virtually the same as if one were to treat the saw (and the various instruments of [10] carpentry) as the cause of the things that come-to-be; for the wood must be divided if a man saws, must become smooth if he planes, and so on with the remaining tools. Hence, however true it may be that Fire is active, i.e. sets things moving, there is a further point they fail to observe—viz. that Fire is inferior to the tools or instruments in the manner in which it sets things moving.

Against “Purely Formal” Explanations of Generation

  • The view

    Socrates “safe” hypothesis regarding “the cause of generation and destruction”:

    Plato, Phaedo 100d–101d (Grube tr.)

    I no longer understand or recognize those other sophisticated causes, and if someone tells me that a thing is beautiful because it has a bright color or shape or any such thing, I ignore these other reasons—for all these confuse me—but I simply, naively and perhaps foolishly cling to this, that nothing else makes it beautiful other than the presence of, or the sharing in, or however you may describe its relationship to that Beautiful we mentioned, for I will not insist on the precise nature of the relationship, but that all beautiful things are beautiful by the Beautiful. That, I think, is the safest answer I can give myself or anyone else. And if I stick to this I think I shall never fall into error. This is the safe answer for me or anyone else to give, namely, that it is through Beauty that beautiful things are made beautiful. Or do you not think so too?—I do.

    Then would you not avoid saying that when one is added to one it is the addition and when it is divided it is the division that is the cause of two? And you would loudly exclaim that you do not know how else each thing can come to be except by sharing in the particular reality in which it shares, and in these cases you do not know of any other cause of becoming two except by sharing in Twoness, and that the things that are to be two must share in this, as that which is to be one must share in Oneness, and you would dismiss these additions and divisions and other such subtleties, and leave them to those wiser than yourself to answer.

  • Objections to the view

    • The “intermittancy” of generation

      GC 2.9, 335b18–20 (Joachim tr.)

      For if the Forms are causes, why is their generating activity intermittent instead of perpetual and continuous—since there always are participants as well as Forms?

    • Ignores other causes

      GC 2.9, 335b20–24 (Joachim tr.)

      Besides, in some instances we see [20] that the cause is other than the Form. For it is the doctor who implants health and the man of science who implants science, although Health itself and Science itself are as well as the participants; and the same principle applies to everything else that is produced in accordance with a capacity.

The Third Principle

GC 2.9, 335a33–b8

Now cause, in the sense of matter, for the things which are such as to come-to-be is that which can be and not be; and this is identical with that which can come to be and pass away, since the latter, while it is at one time, at another time is not. (For whereas some things are of necessity, viz. the eternal things, others of necessity are not. And of these two sets of things, since they cannot diverge from the [335b1] necessity of their nature, it is impossible for the first not to be and impossible for the second to be. Other things, however, can both be and not be.) Hence coming-to-be and passing-away must occur within the field of that which can be and not be.

This, therefore, is cause in the sense of matter for the things which are such as to [5] come-to-be; while cause, in the sense of their end, is their figure or form—and that is the formula expressing the substance of each of them.

But the third principle must be present as well—the cause vaguely dreamed of by all our predecessors, definitely stated by none of them.

Strangely, A. does not refer to the third cause by name, but it should be clear what sort of cause A.’s objections to the “purely material” and “purely formal” accounts of change point to: the mover (typically—among perishable things—the efficient cause).

Robert Howton
Robert Howton
Assistant Professor of Philosophy

I am Assistant Professor of Philosophy at Koç University, Istanbul, specializing in ancient Greek and Roman philosophy and the philosophy of perception.