These remarks serve partly to meet the difficulties pointed out by commentators in regard to the Ten Categories. From the century immediately succeeding Aristotle, down to recent times, the question has always been asked, why did Aristotle fix upon Ten Categories rather than any other number? and why upon these Ten rather than others? And ancient commentators[68] as well as modern have insisted, that the classification is at once defective and redundant; leaving out altogether some particulars, while it enumerates others twice over or more than twice. (This last charge is, however, admitted by Aristotle himself, who considers it no ground of objection that the same particular may sometimes be ranked under two distinct heads.) The replies made to the questions, and the attempts to shew cause for the selection of these Ten classes, have not been satisfactory; though it is certain that Aristotle himself treats the classification as if it were real and exhaustive,[69] obtained by comparing many propositions and drawing from them an induction. He tries to determine, in regard to some particular enquiries, under which of the Ten Summa Genera the subject of the enquiry is to be ranged; he indicates some predicate of extreme generality (Unum, Bonum, &c.), which extend over all or several Categories, as equivocal or analogous, representing no true Genera. But though Aristotle takes this view of the completeness of his own classification, he never assigns the grounds of it, and we are left to make them out in the best way we can.
[68] Schol. p. 47, b. 14, seq., 49, a. 10, seq. Br.; also Simplikius ad Categor. fol. 15, 31 A, 33 E. ed. Basil., 1551.
[69] Scholia ad Analyt. Poster. (I. xxiii. p. 83, a. 21) p. 227, b. 40, Br. Ὅτι δὲ τοσαῦται μόναι αἱ κατηγορίαι αἱ κατὰ τῶν οὐσιῶν λεγόμεναι, ἐκ τῆς ἐπαγωγῆς λαμβάνει.
Brentano (in his treatise, Ueber die Bedeutung des Seienden in Aristoteles, Sects. 12 and 13, pp. 148-177) attempts to draw out a scheme of systematic deduction for the Categories. He quotes (pp. 181, 182) a passage from Thomas Aquinas, in which such a scheme is set forth acutely and plausibly. But if Aristotle had had any such system present to his mind, he would hardly have left it to be divined by commentators.
Simplikius observes (Schol. ad Categ. p. 44, a. 30) that the last nine Categories coincide in the main (excepting such portion of Quale as belongs to the Essence) with τὸ ὄν κατὰ συμβεβηκός: which latter, according to Aristotle’s repeated declarations, can never be the matter of any theorizing or scientific treatment — οὐδεμία ἐστὶ περὶ αὐτὸ θεωρία, Metaphys. E. p. 1026, b. 4; K. p. 1064, b. 17. This view of Aristotle respecting τὸ συμβεβηκός, is hardly consistent with a scheme of intentional deduction for the accidental predicates.
We cannot safely presume, I think, that he followed out any deductive principle or system; if he had done so, he would probably have indicated it. The decuple indication of general heads arose rather from comparison of propositions and induction therefrom. Under each of these ten heads, some predicate or other may always be applied to every concrete individual object, such as a man or animal. Aristotle proceeded by comparing a variety of propositions, such as were employed in common discourse or dialectic, and throwing the different predicates into genera, according as they stood in different logical relation to the Subject. The analysis applied is not metaphysical but logical; it does not resolve the real individual into metaphysical ἀρχαὶ or Principles, such as Form and Matter; it accepts the individual as he stands, with his full complex array of predicates embodied in a proposition, and analyses that proposition into its logical constituents.[70] The predicates derive their existence from being attached to the First Subject, and have a different manner of existence according as they are differently related to the First Subject.[71] What is this individual, Sokrates? He is an animal. What is his Species? Man. What is the Differentia, limiting the Genus and constituting the Species? Rationality, two-footedness. What is his height and bulk? He is six feet high, and is of twelve stone weight. What manner of man is he? He is flat-nosed, virtuous, patient, brave. In what relation does he stand to others? He is a father, a proprietor, a citizen, a general. What is he doing? He is digging his garden, ploughing his field. What is being done to him? He is being rubbed with oil, he is having his hair cut. Where is he? In the city, at home, in bed. When do you speak of him? As he is, at this moment, as he was, yesterday, last year. In what posture is he? He is lying down, sitting, standing up, kneeling, balancing on one leg. What is he wearing? He has a tunic, armour, shoes, gloves.
[70] Aristot. Metaphys. Z. p. 1038, b. 15. διχῶς ὑποκεῖται, ἢ τόδε τι ὄν, ὥσπερ τὸ ζῷον τοῖς πάθεσιν, ἢ ὡς ἡ ὕλη τῇ ἐντελεχείᾳ. The first mode of ὑποκείμενον is what is in the Categories. For the second, which is the metaphysical analysis, see Aristot. Metaph. Z. p. 1029, a. 23: τὰ μὲν γὰρ ἄλλα τῆς οὐσίας κατηγορεῖται, αὕτη δὲ τῆς ὕλης. ὥστε τὸ ἔσχατον καθ’ αὑτὸ οὔτε τὶ οὔτε ποσὸν οὔτε ἄλλο οὐθέν ἐστι.
Porphyry and Dexippus tell us (Schol. ad Categ. p. 45, a. 6-30) that both Aristotle and the Stoics distinguished πρῶτον ὑποκείμενον and δεύτερον ὑποκείμενον. The πρῶτον ὑποκείμενον is ἡ ἄποιος ὕλη — τὸ δυνάμει σῶμα, which Aristotle insists upon in the Physica and Metaphysica, the δεύτερον ὑποκείμενον, ὃ κοινῶς ποιὸν ἢ ἰδίως ὑφίσταται, coincides with the πρώτη οὐσία of the Categories, already implicated with εἶδος and stopping short of metaphysical analysis.
The remarks of Boêthus and Simplikius upon this point deserve attention. Schol. pp. 50-54, Br.; p. 54, a. 2: οὐ περὶ τῆς ἀσχέτου ὕλης ἐστὶν ὁ παρὼν λόγος, ἀλλὰ τῆς ἤδη σχέσιν ἐχούσης πρὸς τὸ εἶδος. τὸ δὲ σύνθετον δηλόνοτι, ὅπερ ἐστὶ τὸ ἄτομον, ἐπιδέχεται τὸ τόδε. They point out that the terms Form and Matter are not mentioned in the Categories, nor do they serve to illustrate the Categories, which do not carry analysis so far back, but take their initial start from τόδε τι, the σύνθετον of Form and Matter, — οὐσία κυριώτατα καὶ πρώτως καὶ μάλιστα λεγομένη.
Simplikius says (p. 50, a. 17):— δυνατὸν δὲ τοῦ μὴ μνημονεῦσαι τοῦ εἴδους καὶ τῆς ὕλης αἴτιον λέγειν, καὶ τὸ τὴν τῶν Κατηγοριῶν πραγματείαν κατὰ τὴν πρόχειρον καὶ κοινὴν τοῦ λόγου χρῆσιν ποιεῖσθαι· τὸ δὲ τῆς ὕλης καὶ τοῦ εἴδους ὄνομα καὶ τὰ ὑπὸ τούτων σημαινόμενα οὐκ ἦν τοῖς πολλοῖς συνήθη, &c. Compare p. 47, a. 27. This what Dexippus says also, that the Categories bear only upon τὴν πρώτην χρείαν τοῦ λόγου καθ’ ἣν τὰ πράγματα δηλοῦν ἀλλήλοις ἐφιέμεθα (p. 13, ed. Spengel; also p. 49).