Binghamton University The Open Repository @ Binghamton (The ORB) The Society for Ancient Greek Philosophy Newsletter 8-1983 Aristotle on Genus and Differentia in the Topics and Categories Herbert Granger University of Texas at Austin, [email protected] Follow this and additional works at: https://orb.binghamton.edu/sagp Part of the Ancient History, Greek and Roman through Late Antiquity Commons, Ancient Philosophy Commons, and the History of Philosophy Commons Recommended Citation Granger, Herbert, "Aristotle on Genus and Differentia in the Topics and Categories" (1983). The Society for Ancient Greek Philosophy Newsletter. 106. https://orb.binghamton.edu/sagp/106 This Article is brought to you for free and open access by The Open Repository @ Binghamton (The ORB). It has been accepted for inclusion in The Society for Ancient Greek Philosophy Newsletter by an authorized administrator of The Open Repository @ Binghamton (The ORB). For more information, please contact [email protected]. Herbert Granger University of Texas at Austin A ristotle on Genus and Differentia in the Topics and Categories Each of A ristotle's early works, the Topics and the Categories»'*' provides important evidence for A ristotle's holding two accounts of the nature of the genus and differentia. In one account genus and differentia are rad­ ically distinct in nature. In the other they are much the same. In this paper I shall make a case for A ristotle's holding each account, sug­ gest why he adopts them, and consider which of the two is the earlier one. I I shall often refer to A ristotle's categorical distinction between sub­ stances (or secondary substances) and non-substances. I take it to dis­ tinguish between the kinds A ristotle deems ontologically significant and the characteristics of the instances of those kinds. The distinction between kinds and characteristics arises from the syntactical distinc­ tion between nouns and adjectives: nouns express kinds; adjectives ex­ press characteristics. The ontologically significant kinds have for their instances the basic entities in A ristotle's ontology. These kinds reveal what kinds of things the basic entities are with respect to their essential nature. For this reason, according to Aristotle, the ontolog­ ically significant kinds are the genera and species of the basic enti— 2 ties. I shall refer to these kinds as "substantial kinds." A species is a complex of its genus ahd differentia (or differen— 3 tiae): for example, the species man is a complex of the genus animal and the differentia two-footed.^ Accordingly, genus and differentia de- 5 fine the species, and they belong necessarily to the species· Because 1 genus and differentia make up the definition of the species» they pro­ vide the account of its basic nature or essence, its ti In einai (Top. 1 .5 .101b 38). In the definition the genus divides the species from things in general, and the differentia distinguishes it from the other things falling under its genus (Top. VI.3.l40a27-29). This brief description, which I derive primarily from the Topics, of genus, differentia and spe­ cies holds for the two accounts of genus and differentia that I discuss. II The Topics and Categories indicate that at one point Aristotle believes that a radical distinction holds between the genus and differentia of substances. This distinction is the categorical distinction between kind and characteristic, which Aristotle marks by holding that the genus alone shows the ti esti, the Mwhat-it-is," of the definiendum and that the differentia shows only a poion t i , a "certain quality," of the defin­ iendum. In Topics 1.5, when Aristotle first introduces the predicables, he defines the genus in these terms: The genus is what is predicated in the ti esti ("what—it—is") of many things differing in species (l.5.102a31-33) Elsewhere it is evident that at least at one point in his thought the genus alone of the elements in the definition represents the ti esti; for Aristotle holds that it is an error not to place the ti esti first in the definition and that this is why the genus is properly placed first, since it is meant to indicate the ti esti (Top. VI.5.142b22-29). The differentia, in contrast with the genus, does not concern the ti esti and is clearly distinct from the genusj a "bad mistake" then is made, accord- 2 ing to Aristotle, if one renders the differentia as the genus: ...for the differentia is the genus of nothing. That this is true is evident; for no differentia signifies the ti esti, hut rather a poion ti (”certain quality”), such as footed and two-footed (Top. IV.2.122bl5-17» cf. VI.6.l44al5-19). These views concerning the roles of genus and differentia are surely A ristotle’s, since in expressing them he does not qualify them hy holding that each ’’seems” to he the case, as he often does when presenting a par­ ticular position in the Topics: moreover, his holding that a ”bad mis­ take” is made when one renders the differentia as a genus strongly sug­ gests that he offers his own view. These distinct roles for genus and differentia obtain not only for substances hut for non-substances as well: for instance, state, the genus of the non-substance virtue, indi­ cates the ti esti of virtue, whereas good, its differentia, does not in— 7 dicate the ti esti but rather a poion ti. The Categories maintains that the genus and species of primary sub­ stances are the only predicates that are substances because they reveal the ti esti of primary substances (5.2b29-33). The Categories also notes that the differentia is not a substance (5.3a21-22). The genus and spe­ cies, like their specimens, are thus found in the category of substance; the differentia is not. The Topics reflects these doctrines: it holds that the genus is in the same category as its species (lV.1.120b3ó-121a 9); it remains silent about whether the differentia is in the same cate­ gory as its subjects; it maintains that the differentia can never signi- 8 fy a "this,” a tode, which on A ristotle’s térros represents a substance. Clearly, as one would expect, A ristotle’s distinction between genus 3 ajad differentia in terms of ti esti sind poion t i » "what-it-is" and "cer­ tain quality»" amounts to a categorical distinction in the case of sub­ stances. The genus as the ti esti of a substantial definiendum is a sub­ stance or substantial kind; the differentia as a poion ti is a non-sub- stance or characteristic in the category of quality. Aristotle simply recognizes explicitly what he finds in the definition» a kind and a char­ acteristic» and marks their categorical difference plainly by his use of ti esti and poion ti. A ristotle’s few remarks in the Topics» which concern the meaning of ti esti» support the interpretation that a predicate in the ti esti of a substance must be a substance or substantial kind. In Topics 1.5» where Aristotle gives his account of the genus as a predicate in the ti esti» he explains that such a predicate is given in response to the question» "what is the object before you?" By way of illustration» he says that if one is presented with a man» one says what it is by saying that it is an "animal" (l02a32-35). Thus a predicate in the ti esti signifies what kind of thing the object is. Indeed» it is hard to see how ti esti could signify anything else. Greek, as well as English, will not allow any­ thing else in response to a question about what something is except a noun and thus a kind expressed by the noun. Moreover, in the case of substances a predicate in the ti esti signifies the object’s kind with respect to its nature, its substantial kind, not just any kind it hap- 9 pens to fall under. This interpretation is supported by Aristotle’s examples of these predicates here in Topics 1.5 and in the important discussion of the categories in 1.9» the only other place in which he indicates the meaning of predicates in the ti esti; for Aristotle limits 4 his examples to the species and genera of the substances and non-sub­ stances used in illustration and at no point offers a differentia as a predicate in the ti esti. (Besides» substantial kinds seem to be the only kinds for substances Aristotle recognizes as kinds; for, when he considers some other kinds a substance might belong to, for example, "boxer” and "runner" in the Categories, he seems to treat them as char­ acteristics (8.10a27—bll)·) It is evident then why the differentia is not a predicate in the ti esti of a substance. Por the differentia, in­ sofar as it is a characteristic, is not a kind and a fortiori not one of A ristotle's substantial kinds. Hence, when it applies to a substantial definiendum, it cannot indicate the latter's ti esti. Aristotle says as much about characteristics in general, when in Topics I.9 he maintains that predicates in the non-substantial categories, when predicates of things outside their categories, namely substances, do not signify a ti esti but only a quality or a quantity or some other non-substantial item (103b35-39)· Besides the important distinctions already noted between genus and differentia. Other perhaps less important differences, but certainly rel­ evant to my discussion, hold between them. As I noted, the genus is properly the first term in the definition because it is the ti esti; it is also the more familiar or knowable term and prior in intelligibility to the differentia.*^ These latter two points of difference, which may in fact come to the same thing, also perhaps reflect the categorical dis­ tinction between genus and differentia; for Aristotle believes that sub­ stances are prior in knowledge to non-substances (Met.