ARISTOTLE’S PRINCIPLE OF INDIVIDUATION
by Dr. Stanley Sfekas

The phrase ‘problem of individuation’ often serves to cover up a conflation of two quite different problems: (1) What constitutes the identity of one individual of a kind over a period of time? (2) What constitutes the difference between two individuals of the same kind at any given time?

In Aristotle the problems are kept clearly apart. To discover whether Aristotle enunciated, in however elliptical or implicit a fashion, something which we may label his ‘principle of individuation’, one must first be clear which of these questions it is to which an answer is desired. I delimit the scope of this study to an examination of Aristotle’s treatment of the second problem.

There are two major views on what is Aristotle’s principle of individuation: one is that matter, the other, that form individuates an entity. A precise formulation of our problem in terms of the Aristotelian metaphysics is difficult to give owing to the obscurity of his metaphysical terminology. In Aristotelian terms the problem is this:

Any individual (tode ti), for instance Socrates, is a whole (synolon) consisting of two components: matter (hyle) and form (eidos).Which of these components, matter or form, differentiates Socrates from Callias?

Aristotle gives different answers to this question in different parts of his Metaphysics (and elsewehere). His answers are not always clear and sometimes seem inconsistent; the clearest passage runs thus: “And when a whole thing has been generated, such-and-such a form in this flesh and these bones; this is Callias or Socrates, and they are different owing to their matter (for this is different) but the same in form (for the form is indivisible).” (Met. Z 8, 1034a 5; Translation mine —note that eidos is everywhere rendered by ‘form’.)

The view that matter is the principle of individuation is the ‘orthodox’ interpretation of Aristotle. For example, Zeller, in his account of Aristotle’s metaphysics states that “Matter is the source of individual existence, in all those things at least which are formed of the union of Matter and Form… Between the Individuals into which the infimae species resolve themselves no difference of kind or Form any longer exists, and consequently they must be distinguished from one another by their Matter.” Zeller is here only restating an interpretation which has always been orthodox from the time of the schoolmen and which still holds the field today.

It was accepted without question by Lukasiewicz, G.E.M. Anscombe and K.R. Popper in the symposium ‘The Principle of Individuation’, Proceedings of the Aristotelian Society, Supplementary Volume for 1953, and was subsequently defended by A.C. Lloyd (Mind 1970). It is held also by Whitney J. Oates, G.R.G Mure, W.D. Ross and many others. The orthodox view has been attacked, however, by (inter alia) Charlton, Regis, Cherniss, Sellars, and recently by J.L. Ackrill (Aristotle the Philosopher, Oxford, 19 81). Some of the critics like Regis and recently Edel go so far as to claim that neither form nor matter is Aristotle’s principle of individuation, (a position which I shall examine in Part II). In this paper I wish to enter the fray on the side of form.

I. THE ATTACK ON MATTER
An interesting line of argument has been introduced by Charlton and endorsed by Regis to attack the orthodox view. It rests on a distinction that is drawn between two sorts of questions which may be asked when people say that matter is Aristotle’s principle of individuation. The one sort reflects a conception of the problem as mainly an epistemological one, for example (a) How do we distinguish one individual from another? The other sort, however, discloses a conception of the problem as a metaphysical one: (b) What makes one individual different from another of the same kind at the same time?

Charlton and Regis argue that proponents of the orthodox view have confused these two sorts of questions. This issue is: To which of these two questions is Aristotle supposed to have found an answer in matter?

Zeller, for example, despite his wording probably held that Aristotle makes matter the answer not to question (a) but to (b), and this seems to be what most people mean when they say that for Aristotle matter is the principle of individuation.

But we can query whether Aristotle held any opinion on question (b) at all, or whether he is not addressing himself to question (a) in 1034a (quoted above). Zeller concedes that Aristotle “did not treat of the principle of individualization with the universality and definiteness that we could have wished” and it is certainly hard to find him formulation question (b) in such terms as his interpreters use. Likewise, when Anscombe asks ‘What is the difference between two individuals of the same kind?’ and takes the answer to be matter, her formulation does not distinguish it from (b), and while she can cite a passage in which Aristotle speaks of difference between individuals of the same kind, she fails to show that it bears on (b) and not (a). In fact, if anything, her treatment of the problem strongly suggests that she has cast it in epistemological terms, for she says “If you ask me what is meant by matter, I can simply tear up a piece of paper and show you the bits.” Popper takes her in this way as well.

While, therefore, it may be that (b) is a genuine question, those who say that Aristotle gives matter as the answer to it, fail to show that he asked it: either the formulations they offer are not found in him, or if they are, it is not shown that they are formulations of question (b) rather than some other question. And if they are formulations of (b), then it can be argued that Aristotle’s answer is not matter.

It is generally agreed that 1034a is the strongest passage on which the traditional interpretation rests. Charlton and Regis are agreed that there is nothing in this passage or its context to show that Aristotle is considering our question (b) rather than (a). Aristotle seems to be answering an epistemological question, not a metaphysical question.

Regis goes on to defend this interpretation from different evidence. His argument centers about doctrinal considerations concerning the possible way in which matter could ‘cause’ individuals to be numerically different from one another. He points out that, in general, it is not possible for matter to be the cause of differences among individuals, for matter is characteristically conceived of by Aristotle as sheer potential having no attributes in and of itself, but rather to be that of which all attributes, and even form, are predicated.

More specifically, matter lacks that attribute which is most proper to individuals: thisness. Thus we are regularly told that an individual substance is a this, an expression which applies to form as well as to the composite. In no case, however, is matter called a ‘this’ while it is several times emphatically denied that it is a ‘this’. This fact alone disallows to matter any role as the cause of an entity’s individuality, identity, or difference from other individuals: the cause of any characteristic, Aristotle holds, must itself contain that characteristic in the highest degree. Matter, itself featureless, cannot be the cause of differences among other things. If anything, matter would seem to be precisely that which requires individuation. It is the conception of matter provided by Aristotle, then, which speaks against construing 1034a as an answer to question (b). To do so would hardly be consistent with this fundamental doctrine of the Aristotelian metaphysics, and in general with the metaphysical priority he gives to form over matter; and, it is therefore best to see 1034a as an answer to (a), i.e. to an epistemological question.

II. THE DEFENSE OF FORM
The view that form is Aristotle’s principle of individuation has been entertained by Charlton, Cherniss, Sellars, Haring, and Ackrill. Texts frequently cited in support are:
(1) shape or form is that in virtue of which a thing is said to be a this (De An., 412a 8-9; cf. Metaph. 1042 a 26-30)

(2) an individual has a form and shape peculiar to it (εκαστον ιδιον εχειν ειδος και μορφην,…DeAn., 407 b 23-4)

(3) we are seeking the cause (and this is the form) through which the matter is a thing (Met. 104l b 7-8)

(4) the causes and elements are distinct for things not in the same genus… and they are distinct even in the same species, not distinct in species, but numerically distinct, as in the case of your matter and your form (ητε ση υλη και τó ειδος) and your moving cause, on the one hand, and mine, on the other, although universally an din form they are the same. (Met. 1071 a 24-9, Apostle tr.; cf. 14-15)

These texts all seem to assert that it is because of any entity’s form that the thing in question is an individual, a this, something different from everything else. Form appears to be thought of as that which makes any individual to be the very individual which it happens to be, and thus to be the principle of individuation as we have understood it.

To determine whether this is in fact the case it will be necessary to investigate the doctrine of ‘individual forms’, for it is this notion which Aristotle seems to be advancing here. This is a controversial question which has been addressed by several commentators. Cherniss, for example, citing texts including and supplementing some of those above maintains that Aristotle held that “all particulars of the same species have numerically different forms.” Likewise, Sellars, Haring and Ackrill have re-affirmed the doctrine of individual forms, while both Albritton and Lloyd have spoken against it. Since much of the discussion centers about the notion of form as a this, it will be of some help to set out the ways in which form and composite are each thisses.

The focus of the discussion is Aristotle’s use of the expression tode ti. In general Aristotle holds that a substance is a tode ti. An expression for a substance such as ‘a horse’ is an expression for a tode ti (c.f. Met. Z 1028a 11-12); it belongs to a substance above all to be a tode ti; only a substance is just what is an individual, and does not have to be related to anything else to be identified or individuated. Substances are what are primarily οντα. As Barnes has put it:

‘This so-and-so’ translates the Greek ‘tode ti’, an unorthodox phrase which Aristotle nowhere explains. What he seems to have in mind can perhaps be expressed in the following way. Substances are things to which we can refer by use of a demonstrative phrase of the form ‘this so-and-so” they are things that can be picked out, identified, individuated. Socrates, for instance, is an example of a ‘this so-and-so’; for he is this man — an individual whom we can pick out and identify.

Aristotle’s most characteristic employment of the term tode ti is in reference to the composite: “the entire this is Callias or Socrates, as in the case of this bronze sphere”(10 33b 24-5). At times a this is even contrasted with form or essence alone: ” ‘form’ signifies a such, and this is not a this” (1033 b 21-2); “there is some matter in every thing which is not an essence and a form by itself but is a this” (1037 a 1-2). Furthermore, the term is so often coupled with the notion of separation that one might suppose that it refers exclusively to composites, for example: “substance is not a universal, but rather a this and a separate thing” (1060 b 21-2); “to be separate and to be a this is thought to belong most of all to substance” (1029 a 27-8).

In other passages, however, tode ti is used quite differently and designates form alone. Thus: “an essence is just a this, whereas if something is said of something else we do not have just a this; for example a white man is not just a this” (1030 a 3-5, Apostle tr.). Now what are we to make of Aristotle’s use of this term? Is it merely arbitrary and capricious? Is the term perhaps an equivocal? Instead of deciding upon this issue, however, let us merely recognize, in view of the many texts in evidence that both form and composite are said to be thisses. It would follow, then, that they are both individual. The problem now becomes: Is the individuality of the composite caused by and derived from that of the form? If the answer is affirmative, and only if it is, form will be the principle of individuation.

That the answer is negative is argued by Regis (who, it will be recalled, rejects both form and matter as Aristotle’s principle of individuation) by appeal to the following considerations. Aristotle’s regular doctrine from the Categories through the Metaphysics is that it is the singular sensible composite which is primary in substance and exists in the fullest sense. But if the composite is primary, Regis argues, then form can be no more causal of individuality than matter. As was true of matter, the composite cannot exist without form; but neither can form exist without matter. In no sense, then, does the composite, which alone is “separate without qualification” (1042 a 30-31), derive its existence from form, or, indeed, from anything else unless it be a moving cause in the cause of generation of substances:
The form of a composite is individual then, only in the same sense in which its matter is individual, namely, it is just the form (or matter) which the already individual composite happens to have. Form, therefore, is no more a principle of individuation than matter.

Now I wish to take issue with this analysis. Regis’s argument warrants scrutiny, for it represents a position commonly taken, and which, I submit, commits a fundamental error in Aristotelian exegesis. I agree that from the beginning Aristotle views the material individual object as the primary sort of being, and that he holds to the primacy of the individual throughout his career, despite difficulties he discovers as he goes along, and despite modifications and clarifications these difficulties require him to make in his notion of substance. Indeed, in the Categories, the individual is considered primary because the universal depends on it for being, and the individual property for its identity, if not for its being. Yet there are other candidates for the title of primary substance, and each one has a claim that must be taken seriouly. One is the universal, which has the advantage over the material object of being knowable, rather than merely sensible. But Aristotle argues that actual as opposed to potential knowledge, is of the individual material object. Another candidate is matter, which seems to be that of which everything else, including what Aristotle has been calling substance, is predicated. Aristotle’s strategy is to show that a substance must be, as matter is not, a unified and identifiable entity; only then can it serve as a reliable subject of predication. A third candidate is the combination of matter and form, ie., the composite, which he explicitly rejects in Z 3. By the time he writes the middle books of the Metaphysics which constitute his most mature work on substance, Aristotle has considerably sharpened his concept of priority in support of his argument that substance is prior to other things, and he has shown how form or essence makes what would otherwise be mere matter a substance by providing it with what any entity with a claim to priority must have: criteria for continuity and individuation. Aristotle finally identifies substance and essence, without abandoning his view that the individual material object is the primary sort of being.

Understanding Aristotle’s position thoroughly requires working out what he says about the relation between a substance and its essence. I shall argue that Aristotle identifies substance and essence as a response to problems about the transitoriness and indefinability of particulars: if one understands that a substance is a persistent form that is at any time associated with some matter or other but not identical with it, then one can see how and to what extent a substance abides through change and so can be known. A substance is the sort of thing it is by virtue of its form or essence, which is therefore at least a necessary condition of it. I wish to argue for a further advance, suggested by Hartman, namely that an essence is a sufficient as well as a necessary condition of a substance, and even that the relation between each substance and its essence is identity.

Some passages in Metaphysics Z offer strong evidence in favor of identifying substance and form or essence. Aristotle has asked at the beginning of the book what qualifies as substance; and in the last chapter, having explored all the alternatives he can think of, Aristotle concludes: “so what we are looking for is the reason why the matter is some particular thing; and that is the form” (1041 b 7ff.; c.f. 1041 a 28). He has expressly eliminated matter, the composite and the universal as candidates for substance. What remains is the form, which, asAristotle says elsewhere, is truly an individual — thus Met. H l 1042 a 29, Θ 7 1049 a 35, Λ 3 1070 a 11ff., where he calls form a ‘this’. The sixth chapter of Met. Z is devoted to proving that a primary substance is identical to its essence: Clearly, then, each primary and self-subsistent thing is one and the same as its essence (to ti en einai). The sophistical objections to this position, and the question whether Socrates and the essence of Socrates are the same thing, are obviously answered by the same solution… We have explained, then, in what sense each thing is the same as its essence, and in what sense it is not. (1032 a 4-10; translation mine).

Aristotle’s position is that it is form or essence that persists through change of matter. This a corellary of what Aristotle asserts in the famous Cat. 5 4a10 ff.; substance survives accidental change. And what counts as a substance surviving accidental change? What counts is the persistence of the essence. Once Aristotle has developed a notion of form that is virtually indistinguishable from essence, it stands to reason that matter will be in the same position as accident in respect to change. Aristotle says at Met. Z 3 1029 a 3 that it may turn out to be form that is substrate as substance is supposed to be substrate, and so it does. The notoriously difficult term usually translated “essence” — to ti en einai, “what was to be” — suggests the importance for substance of persistence through time. The verb en is in the imperfect tense, which in this sort of use (which grammarians call the “philosophical imperfect”) probably conveys omnitemporality or even timelessness and thus freedom from contingency. It is what the substance always is as long as it exists, and so what it necessarily is. And it is in this sense a substrate.

Again, it is clearly only the individual form, not the universal, that is what is most permanent about the individual universal, that is what is most permanent about the individual substance; and there is abundant evidence in the Metaphysics that Aristotle is indeed committed to the individual form. When he says that substance is form, he cannot very well mean that the object of his search is the universal. That he has never believed, and he firmly rules it out again in Ch. 3 of Book Z, in which he states that things whose substance and essence are one are themselves one (1038 b 14f.). His doctrine that the soul is the form of the living body is alluded to often in the middle of books of the Metaphysics, usually in a way that makes it clear that each person has his own soul—thus Z 10 10 35 b25ff., for example. And there are a number of passages in which he countenances individual essences.

Thus far an essence is a necessary condition of a substance, and the essence in question is a particular essence. What remains is to show at least that the existence of a particular form or essence is a sufficient condition of the existence of a particular substance, that is, the whole material object. Metaphysics Z 10 and 11 seem to be occupied with that task where Aristotle says that something’s having a certain essence may put certain requirements on its matter as well: e.g., a man cannot be made of just any old sort of material, but must be made of the sort of stuff that enables him to do what men characteristically do. And now it is clear why Aristotle would want to deny that a substance is a compound of form and matter, as he does in Z 3 1029 a 30-32, peremptorily. Even if the substance in question must have a certain sort of matter, the particular matter of which the substance is made could disappear while the substance itself remains. To say that a substance still exists is to say that its form still exists; to say it is no more is to say that its form is no more, though its matter may abide. So Aristotle says: “those things which are as matter or are combined with matter are not the same (as their essences)…” (Z 11 1037 b 4f). Thus substance is not this form plus this matter. If it were, one could not, as Hartman notes, step into the same river twice. On the other hand, the essence is a sufficient condition of some matter or other of a certain sort. As Hartman puts it: “…if there is the essence of a river on your land, it follows that there is some water for you to step into.”

Now it might be objected that if a substance is a material object, it is not a form but a combination of form and matter. But when Aristotle does say a substance is form and matter, he only means that (for example) Socrates is associated with some matter of the appropriate sort at all times. It does not follow that he is identical with something more than his essence, for his identity with his essence does not excuse him from necessarily having matter. Socrates also necessarily has some colour or other, and some weight, and location. But Socrates is not a combination of his form and his colour. It is in just that sense that Aristotle denies (at Z 11 1037 b 4-7) that things that are combined with matter are the same as their essences, because of the particular matter of which the thing is made is neither a necessary nor a sufficient condition of its existence. For the same sort of reason, the individual man is not a combination of form and matter. One of the most important lessons to be drawn from Z 10-12 is that the relation between form and mater is not a relation or combination of logically independent entities of equal standing. They are not elements of a particular thing, nor are they both properties of a particular thing, nor is either a property of the other.

Matter is not an equal partner to the form in determining what—or that—the thing is; for form is necessary and sufficient for the thing and matter is at most necessary in a way. Of course, substances require some sort of matter, and the individual form cannot exist alone; perhaps the resistance to identifying a material object with its form comes of a mistaken impression that the identity of substance and form makes substances matterless. But it does not, nor does it make them accidentless. A substance is an essence (a form); it has accidents (matter).

D.J. Allan has expressed the same point thus: To what category of Being does the form belong? The answer, again, is ‘the substantial’; and Aristotle maintains, what is at first somewhat surprising, that the form which binds together, and perhaps animates, the materials is more truly substantial than the complex thing. This means, in effect, that it is form which is substantial par excellence, having that priority over the form-matter complex which ‘the substantial’ has among the types of Being. In more concrete terms, ‘man’ is substantial only because ‘human soul’ is so, and ‘house’ the compound of form and matter, only because the form of a house is so…

Now it may cause some surprise that a form or essence which among familiar objects cannot exist in vacuo, but is the form of a matter, is nevertheless more real than the complex entity whose form it is; but Aristotle stands firm in this position…

He equates form with ‘essential nature’ or ‘what it is to be so-and-so’. It is not the choice of materials which makes a certain structure a house, thought one might pay some regard to them in deciding whether it is properly called by that name. The criterion is whether it exhibits ‘what it is to be a house’, which in the great case of this and other man-made objects will to a great extent coincide with a purpose, ‘a structure effectively giving shelter to men and their possessions’. A definition is an attempt to grasp the essential nature in words; if it is composed of parts, they will correspond to the parts either of the form-matter complex, or of the essence. A thing may look as though it had the essential nature, but not in fact have it. A glass eye, even if well imitated, and worn in the appropriate part of the body, never had ‘what it is to be an eye’ (i.e. the capacity for seeing); a hand severed from the body once had, but has now lost, ‘what it is to be a hand’. In general, an essence activates and unites the matter without residing as some particular point within it.

The same interpretation is put forward lucidly by G.E.R Lloyd:

Certainly when he considers ‘essence’ and ‘form’ he shows that these have special claims to the title of substance, for while substance is applied in one sense to the individual complex of form and matter, in another it is used of the form alone. He suggests at 1028 a 32 f. that two of the marks of substance are that it is first in definition and in order of knowledge. But we know a thing, he says at 1031 b 20 f., for example, when we know its ‘essence’ or what it is to be that thing. Again he says at 1042 a 17, for instance, that the definition of a thing is the formula of what it is to be that thing. In Z, Ch. 17, especially, when he makes a fresh start in his inquiry, he argues that the object of their investigation is the cause of a thing, and that this is the ‘essence’, that which makes a thing what it is, or the form. And finally in H, chh. 2 and 3, where he considers substance as actuality, he shows that this is the form.

Both Allan and Lloyd are agreed that according to Aristotle’s criteria of definability, knowability, permanence and actuality, the root idea of substance is ‘the what it is to be a thing’, the ‘to ti en einai’, or the form. Form is therefore prior both to individuals and to matter. As Haring putts it: “A substantial form is a per se what. An individual has whatness from form. Prime matter stands at even a further remove from form.” Ackrill, writing in the same spirit states:

Aristotle’s general position then is this. It is individuals in real species that are basic substances (independent identifiable subjects of predication), and it is their essence or form that gives them this substantial being. So of the trio form, matter, compound, form is ‘primary substance’, since it is the ‘cause’ of the substantial being of the compound.

But this prior form is the essence. Now a critic of this view might ask ‘why does not the claim of essence to count as substance fall victim to the argument Aristotle levels in Z 13 against the claim of universals?’ How can man be the essence of both Callias and Socrates, if Callias and Socrates are not themselves identical? The way in which this difficulty may be tackled is to argue that for Aristotle man is not Callias’ essence, but his psyche or soul is. As Ackrill argues:

…One may suggest that Aristotle does or should accept the idea of individual essences (so that man no longer counts as Callias’ essence). There are several passages in which Aristotle uses the terms ‘soul’ and ‘body’ in discussing men and their essence. In these passages it is soul rather than man that appears as the individuating form of Callias – not his species but his life. Since ‘soul’ has a plural and often works like a count-noun, it is quite easy to suppose that Callias has one soul and Socrates another, and that these souls are individual essences.

Finally, Cherniss makes the same argument thus:

…it appears that, when Socrates and Callias are said to differ because of their matter, the form which Aristotle has in mind is the specific form “man”…but, when the form of the individual is said to be peculiar to him, the form is not “man” but the soul…Living organisms, then, have form in two senses; and Aristotle’s reference to the different forms of individuals within a single species are due to the fact that for him the soul peculiar to each body is also the form, the primary substance of the organism.

In conclusion, I wish to emphasize that in my view the greater threat to my thesis does not issue from the orthodox interpretation, but rather from that view which denies that either form or matter is the principle of individuation, on the ground that the sensible composite is primary. As regards the orthodox interpretation, in my view, Charlton’s insightful distinction between the epistemological and metaphysical aspects of questions of individuation, represents a signal contribution to the literature on the subject; for once we are freed from the shackles of that vexatious passage, 1034 a, which, on its face, seemed literally to be saying that matter differentiates Callias from Socrates, we can find no other supportive evidence for the claim that matter is the principle of individuation. Indeed as we have seen, every doctrinal consideration tends to point to the contrary conclusion. On the other hand, the claim that individual material objects are primary is refuted only by appeal to a subtle and complex exegetical analysis replete with textual obscurities and difficulties. The doctrine of substantial forms or individual essences has to be established, and the intricate relation between substance and essence has to be worked out. The definitive case for these claims remains to be made, for it requires nothing less than an exhaustive reconstruction of the entire ‘first philosophy’. But if we wish to develop Aristotle’s thought beyond the text to such matters as the principle of individuation, this, I suggest, is the enterprise that perennially challenges us.