What is an
Part One

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A minature from the 15th century, Brussels

About the Classical Conception of Individuality

In the foregoing we saw that a substance must be a Totality, i.e. a totality of parts and determinations. Ultimately a Substance must be a concrete totality, because Substance is first of all FIRST SUBSTANCE, and that is : Something-that-is-not-in-something-else-anymore, i.e. not received by any subject (substrate), and as such it is then concrete and individual. A Substance, namely, is FIRST SUBSTANCE by virtue of PRIME MATTER, and this is, among other things, a (sub-) principle of being an individual [ PRIME MATTER of a thing is the ultimate substrate of that thing, which underlies, i.e. lies under, all content (FORM) of that thing in question, while having itself no content whatsoever. Therefore it is a principle of the possibility of radical change. When something changes, something in it must remain, while the rest is replaced. In the case of radical change this something that remains is PRIME MATTER. If things did not possess PRIME MATTER, then radical change would be impossible, because then it would be a creation (out of nothing) of something entirely new. ]. A genuine Substance accordingly is an individual. This aspect of being a Substance is especially prominent and emphasized in Aristotle's Metaphysica.
But what then is precisely an individual?
The classical definition reads : an individual is undivided in itself, and divided from others ( indivisum in se et divisum ab alio ). But the aspect of being undivided, as well as the aspect of being divided, is not without problems, as soon as we -- accompanied by modern insights -- investigate the constitution of Reality (the Universe) more closely. Which view of the concept of Individuality one accepts, is crucial for a thematical evaluation of the Substance-Accident structure, assumed by Thomism, with respect to (the ontological constitution of) beings.

Which view of (being an) individuum. i.e. which definition of INDIVIDUUM, is appropriate for figuring in the ontological scheme of Substance and Accident? Is it the here-and-now individuum that should be seen as a Substance, or is it the individual during its complete historical existence, the historical individuum, i.e. should Socrates-here-and-now be considered THE individual, and accordingly THE substance, or Socrates-during-his-complete-lifetime? In the case of biological beings the latter view seems the most appropriate. In that case we could say that the individuum is extended over the time-span between two substantial changes: of which the first brings the individual into being, and the second terminates it. But the phenomenon of metamorphosis, which can be observed in many insects and echinoderms (starfishes and their kins), shows a very radical change of the organism during this time-span, which may force us to consider a revision and further elaboration of the concept of substantial change in connection with (the particular view of) individuality [ A substantial change is supposed to be a change into another substance or substances, while an accidental change leaves the substance the same and implies only a substitution of one (or more) determination by another, for example Socrates becomes tanned by the sun.]. St Thomas' principle of individuation, laid down in his commentary of (a work of) Boëthius, Expositio super Librum Boëthii de Trinitate, Quaestio 4, Art. 2 seems to account for this phenomenon however, because of his (conception of) unterminated dimensions (dimensiones interminatae). In Chapter 2 of De Ente et Essentia St Thomas, after having established that the Essence of each material sensible substance consists of Matter and Form, says the following (after line 65):

"But matter is the principle of individuation. From this it might perhaps appear to follow that an essence which includes in itself matter along with form is only particular and not universal. And from this it would follow that universals would not have a definition, if essence is that which is signified by a definition. We should notice, therefore, that the principle of individuation is not matter taken in just any way whatever, but only designated matter. And I call that matter designated which is considered under determined dimensions. Such matter is not placed in the definition of man as man, but it would be placed in the definition of Socrates, if Socrates had a definition. Rather, it is nondesignated matter which is placed in the definition of man. For this bone and this flesh are not placed in the definition of man, but bone and flesh absolutely. These latter are man's nondesignated matter."
About those dimensions St Thomas says the following in his Summa contra Gentiles, S.G. IV Cap. 65 (comments are added between square brackets [ ] ):
"...because those things which belong to the same species, multiply themselves only on the basis of the individuum. That's why many whitenesses are not grasped [by the intellect] until they are in different subjects [substrates]. A multitude of [mathematical] lines can [as such] be grasped even when they are considered in themselves [i.e. as such]. The diverse [possible] position[s], after all, belonging per se [i.e. by necessity] to the line, is sufficient for a multiplicity of lines [i.e. the line can be divided up into several pieces, by virtue of the ordered dispersion of its (potential) parts]. And because only dimensive quantity [which had been examplified by a line] by itself has [the ability] that a multiplication of individuals of the same species can take place, it appears that the root of such a multiplication lies in the dimension. So [in the text : quia] also in [things belonging in] the genus [ i.e. category] of SUBSTANCE the multiplication proceeds by virtue of the dimension of matter, which cannot be understood unless we consider the matter [as standing] under dimensions : because if we abstract from quantity, all substance then is indivisible, as is clear with the Philosopher [With "the Philosopher" St Thomas always means : Aristotle] in the first Book of his Physics. It is clear however that in the remaining genera [categories][namely those] of the accidents, the multiplication of individuals of the same species proceeds by virtue of the subject [substrate]."
Matter-under-dimensions thus individuates the subject (the substrate), while this in turn individuates the accidents. These accidents however do not become individuals, but become individual. Individuals are generated along with (and by virtue of) the multiplication (-ability) of a Form. So the Form then is communicable to a multiplicity of 'cases'.

In Chapter 2 of De Ente et Essentia St Thomas determines how Essence is signified by the term HUMANITAS (= human nature) -- in contrast with the term HOMO (= man). This proceeds "cum precisione materie designate que est principium individuationis" [ In more classical Latin this phrase runs as follows : cum praecisione materiae designatae quae est principium individuationis ]. The translation reads : "with removal of designated matter which is the principle of individuation". So the term humanitas points to the Essence of a human being, and it does so by abstracting (i.e. not considering) designated matter, which implies not considering that something that causes something to be an individual) [ precisio means a cut-off (from the front end)]. In Chapter 3 he maintains that being-present-in-this-or-that-singular does not belong to the proper ratio (ratio propria, the essential meaning) of Essence, i.e., for something to be the Essence of something (else), does not necessarily imply that it must reside within something. The question is how we should interpret this assertion. Thematically it appears correct to me that the cutting-off of the designated matter should be equivalent to the cutting-off of the particular (the aspect of being just this individual, pointed to with the finger), and not (equivalent) to the cutting-off of the individual. Accordingly 'Socrates' (in 'Socrates is a human being') must be interpreted as : 'Socrates-for-example', and not : 'Socrates-as-Socrates'. In 'Socrates-for-example' the particular is not considered, but the aspect of being individual is, and accordingly 'Socrates-for-example' stands for the individual Essence. And this should be the right way to proceed, when we do not want to assume the existence of universals in extramental Reality. In such a view only the term (for instance 'man') is universal, because it is ONE sign for MANY things (in Reality).
If an individuum is thus characterized, then this must be expressed in the formulation of a principle of individuation. To be an individual is to be totally determined, but not totally fixed, but first in that direction totally determined, then in another direction (totally determined). So it is always determined in some one direction (For example an individual of a butterfly species is during a certain time-span totally determined in the 'caterpillar direction', later it is totally determined in the 'winged insect direction'). This possible variation in the direction in which something is totally determined should not only be extended over the time-span of the existence of an individuum, but also spatially, i.e. the variation should be extended also over different individuals, Plato, Socrates, etc. Thus the designation (delimitation) of matter (that as such figures in the principle of individuation) should not totally be fixed, but it should be fixed disjunctim, i.e. either totally determined in that direction, or totally determined in this direction, etc. As has been said, this appears to be satisfied by the principle of individuation proposed by St Thomas in his Commentary on Boëthius' treatise on the Trinity. If so, then indeed only the particular is being abstracted, resulting in an individual Essence, and consequently not in an extramentally existing universal, i.e. not a universal existing in extramental Reality.
But when St Thomas in Chapter 2 of De Ente et Essentia asserts that Essence, of, for example, Man, is signified with the term humanitas, cum precisione materie designate que est principium individuationis, and when he indeed means the Essence as it is in itself [ NOTE 1 ], then it seems that he not only abstracts (i.e. conceptually removes) the (aspect of the) particular, but also the (aspect of the) individual, and consequently assumes the existence of a universal in extramental Reality (universale in re). Because not until the Essence -- at first taken absolutely -- is received in this or that singular -- and then it is not taken absolutely anymore -- it is not individual. Essence, taken absolutely, is accordingly as such not individual. And if this possibility of considering an Essence is justified by the ontological constitution of a thing, then we have a universal existing in extramental Reality. See also St Thomas in In VII Met. lectio 9, nr. 1468--1481, especially nr. 1473.
Let us cite StThomas, nr. 1468--1481, to get the flavor of a medieval discussion, in the present case within an exposition (commentary) of Aristotle's Metaphysics ( my own comments are placed between square brackets [ ]):

(From St Thomas' Commentary on book VII of the Metaphysics of Aristotle) Last part of nr. 1467.
"And for this reason they think that no material parts are given in the definition which designates the species, but only the formal principles of the species. This appears to be the opinion of Averroes and of certain of his followers.

nr. 1468.
But this seems to be opposed to the opinion of Aristotle. For he says above, in Book VI, that natural things have sensible matter in their definition, and in this respect they differ from the objects of mathematics. Now it cannot be said that natural substances are defined by something that does not pertain to their being. For substances are not defined by addition but only accidents, as was stated above. Hence it follows that sensible matter is part of the essence of natural substances, and not only of individuals but also of species themselves. For it is not individuals that are defined but species.

nr. 1469.
And from this arises the other opinion, which Avicenna entertains. According to this opinion the form of the whole, which is the quiddity [i.e. the whatness (of something)] of the species, differs from the form of the part as a whole differs from a part. For the quiddity of a species is composed of matter and form, although not of this individual matter and this individual form. For it is an individual, such as Socrates or Callias, that is composed of these. This is the view which Aristotle introduces in this chapter in order to reject Plato's opinion about the Ideas. For Plato said that the forms of natural things have being of themselves without sensible matter, as though sensible matter were in no way a part of their species. Therefore, having shown that sensible matter is a part of the species of natural things, he now shows that there cannot be species of natural things without sensible matter. For example, the species man cannot exist without flesh and bones. And the same is true in other cases.

nr. 1470.
Now this will constitute the third method by which the Ideas are rejected. For Aristotle rejected them, first, on the grounds that the essence of a thing does not exist apart from the thing to which it belongs. Second, on the grounds that forms existing apart from matter are not causes of generation either in the manner of a generator or in that of an exemplar. And now in this third way he rejects Plato's thesis on the grounds that the intelligible expression of a species includes common sensible matter.

nr. 1471.
Hence in solving this difficulty he says that the word part is used in several senses, as was explained in Book V. For example, in one sense it means a quantitative part, i.e., one which measures a whole quantitatively, as half a cubit is part of a cubit, and the number two is part of the number six. But this type of part is at present omitted, because it is not his aim here to investigate the parts of quantity, but those of a definition, which signifies a thing's substance. Hence it is necessary to investigate the parts of which a thing's substance is composed.

nr. 1472.
Now the parts of substance are matter and form and the composite of these. And any one of these three -- matter, form and the composite -- is substance, as was stated above. Therefore in one sense matter is part of a thing, and in another sense it is not, but this is true "of those things of which the intelligible expression or specifying principle consists," i.e., the form. For we understand concavity as form and nose as matter, and snub as the composite. And according to this, flesh, which is the matter or a part of the matter, is not a part of concavity, which is the form or specifying principle. For flesh is the matter in which the form is produced. Yet flesh is some part of snub, provided that snub is understood to be a composite and not merely a form. Similarly, bronze is a part of a whole statue, which is composed of matter and form. But it is not a part of the statue insofar as statue is taken here in the sense of the specifying principle, or form.

nr. 1473.
And to insure an understanding of what the specifying principle is and what the matter is, it is necessary to point out that anything which belongs to a thing inasmuch as it has a specific form belongs to its specific form. For example, inasmuch as a thing has the form of a statue, it is proper for it to have a shape or some such quality. But what is related to a form as its matter must never be predicated essentially of a form. Yet it must be noted that no kind of matter, be it common or individual, is related essentially to a species insofar as species is taken in the sense of a form, but [ only ] insofar as it is taken in the sense of a universal. For example, when we say that man is a species, common matter then pertains essentially to the species, but not individual matter, in which the nature of the form is included.

nr. 1474.
Hence it must be said that the definition of a circle does not include "the definition of its segments," i.e., the parts divided from a circle, whether they be semicircles or quarter circles. But the definition of a syllable includes that "of its elements," or letters. And the reason is that "the elements," or letters, are parts of a syllable with reference to its form, but not to its matter. For the form of a syllable consists in being composed of letters. The divisions of a circle, however, are not parts of a circle taken formally, but of this circle, or of these circles, as the matter in which the form of a circle is produced.

nr. 1475.
This can be understood from the rule laid down above. For he had said that what belongs essentially to each thing having a form pertains to the form, and that what belongs to the matter is accidental to the specific form. But it belongs essentially to a syllable, which is composed of letters. Now the fact that a circle may be actually divided into semicircles is accidental to a circle, not as a circle, but as this circle, of which this line, which is a material part of it, is a division. Hence it is clear that a semicircle is part of a circle in reference to individual matter. Therefore this matter, i.e., this line, is more akin to the form than bronze is, which is sensible matter, when roundness, which is the form of a circle, is produced in bronze. Because the form of a circle never exists apart from a line, but it does exist apart from bronze. And just as the parts of a circle, which are accidents in reference to individual matter, are not given in its definition, in a similar fashion not all letters are given in the definition of a syllable, i.e., those which are parts along with matter, for example, those inscribed in wax or produced in the air [ namely when spoken ], since these are already parts of a syllable as sensible matter.

nr. 1476.
For not all the parts into which a thing is corrupted, when it is dissolved, must be parts of its substance. Because even if a line when divided is dissolved into two parts, or a man into bones, sinews, and flesh, it does not therefore follow, if a line is thus composed of halves, or a man of flesh and bones, that these are parts of their substance. But these things are constituted of these parts as their matter. Hence these are parts of "the concrete whole," or composite, "but not of the specifying principle," i.e., the form, or "of that to which the intelligible expression belongs," i.e., of the thing defined. Therefore no such parts are properly given in the intelligible expressions of these things.

nr. 1477.
Still it must be noted that in the definitions of some things the intelligible expressions of such parts are included, i.e., in the definitions of composite things, of which they are the parts. But in the definitions of other things this is not necessary, i.e., in the definitions of forms, unless such forms are taken along with matter. For even though matter is not part of a form, it must be given in the definition of a form, since the mind cannot conceive of a form without conceiving matter. For example, organic body is included in the definition of soul. For just as accidents have complete being only insofar as they belong to a subject, in a similar fashion forms have complete being only insofar as they belong to their proper matters. And for this reason, just as accidents are defined by adding their subjects, so too a form is defined by adding its proper matter. Hence when matter is included in the definition of a form, there is definition by addition, but not when it is included in the definition of a composite.

nr. 1478. Or his statement "unless taken together they constitute the intelligible expression of the thing" exemplifies his remark that "in other cases it need not include them." For in such cases it is not necessary that the material parts should be included in the definition, i.e., in the case of those things which are not taken together with matter, or which do not signify something composed of matter and form. This is evident. For since matter is not included in the intelligible expression of some things but is included in that of others, there can be some things which "are composed of these as the principles into which they are dissolved," i.e., the parts into which things are dissolved by corruption. And these are the things whose definitions include matter. But there are some things which are not composed of the foregoing material parts as principles, as those in whose definitions matter is not included.

nr. 1479.
And since matter is included in the definitions of those things which are taken together with matter but not in those of others, "hence all things which are matter and form taken together," i.e., all things which signify something composed of matter and form, such as snub or brazen circle, such things are corrupted into material parts, and one of these is matter. But those things which are not conceived by the mind with matter but lack matter altogether, as those which belong to the notion of the species or form alone, these are not corrupted "in such a way as this," i.e., by being dissolved into certain material parts. For some forms are corrupted in no way, as the intellectual substances, which exist of themselves, whereas others which do not exist of themselves are corrupted accidentally when their subject is corrupted.

nr. 1480.
Hence it is evident that material parts of this kind are the principles and parts of those things "which come under these," i.e., which depend on these, as a whole depends on its component parts. Yet they are neither parts nor principles of the form. And for this reason when a composite, such as a statue made of clay, is corrupted, "it is dissolved into its matter," i.e., into clay, as a brazen sphere is dissolved into bronze, and as Callias, who is a particular man, is dissolved into flesh and bones. Similarly a particular circle depending on these divided lines is corrupted into its segments. For just as Callias is a man conceived with individual matter, so too a circle whose parts are these particular segments is a particular circle conceived with individual matter. Yet there is this difference, that singular men have a proper name, and therefore the name of the species is not applied equivocally to the individual [ i.e. Socrates AS Socrates is A HUMAN BEING only per accidens (= in a contingent way only), while Socrates as Socrates-for-example is A HUMAN BEING per se (= in an intrinsic way) ], but the term circle is applied equivocally to the circle "which is called such in an unqualified sense," i.e., in a universal sense, and to singular particular circles. And the reason is that names are not given to several particular circles but they are given to particular men.

nr. 1481.
Moreover it must be noted that the name of the species is not predicated of the individual in the sense that it refers the common nature of the species to it, but it is predicated of it equivocally, if it is predicated in such a way that it signifies this individual as such. For if I say "Socrates is a man," the word man is not used equivocally [ it then refers to Socrates only ]. But if this word man is imposed as a proper name on some individual man, it will signify both the species and this individual equivocally. It is similar in the case of the word circle, which signifies the species and this particular circle equivocally [ similarly sounding, but not communicating the same meaning. Here, circle' means the species (the circle as a kind of figure), as well as this individual circle ]."

St Thomas devoted much of his intellectual quest to the study of Aristotle's works (in a Latin translation), so his metaphysics came to be strongly influenced and inspired by the great Greek philosopher.


An individual is a complete determination of a being (i.e. it is a being that is completely determined), either in this direction, or in another direction, and also possibly alternating between determination-directions. And therefore an individual cannot be instantiated anymore (like for instance universals which can be so instantiated). This being-totally-determined could perhaps be equated with EXISTING. The view of individuality just given, as something that is not instantiable anymore, or, perhaps equivalently, something that is totally determined, seems to me however far from a complete characterization of individuality. Because the to-be-a-self (the possession of an identity) is already presupposed by the term 'something'. Still some conditions must be satisfied, that legitimitate us to speak in terms of 'something'. St Thomas tries to formulate these conditions in his principle of individuation.

A more or less complete principle can perhaps be found by combining his expositions (See BOBIK, J., 1954, Dimensions in the Individuation of Bodily Substances, Philosophical Studies, 4, p. 60-79), namely what we find in :

  1. The Commentary on Boëthius' treatise on the Trinity. The dimensiones interminatae (unterminated dimensions), with respect to numerical unity.
  2. De principio individuationis, and De natura materiae et dimensionibus interminatis [ These treatises are perhaps not written by St Thomas, but they were written in that period and are also thomistic in character ]. The materia prima (prime matter), with respect to being a first substance. First substance is (as a term) not predicable anymore and thus not communicable anymore (over several cases).
  3. De Ente et Essentia. Quantitative total (but all the time changing) determination to the here-and-now by the materia signata (designated matter). Matter, under determined quantity : See (also) De principio individuationis.
The phenomenon of being-an-individual could then perhaps also be used to discriminate between an accident and a substance. A quality, for example, is in itself universal, but as received by a substance (i.e. as a determination of a substance) it is individual, albeit just per accidens, because it is individual by virtue of the individuality of the supporting substance. A quality can however never be an individual (an individuum). A substance, i.e. a totally determined substance, always is individual as well as an individual.
We will investigate these matters conceptually as well as by means of concrete examples (not only by means of the example MAN).

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