Note 39 — Chapter IX · TOPICA. I.

Topic. I. viii. p. 103, b. 6-19: ἄλλη δὲ πίστις ἡ διὰ συλλογισμοῦ.

It will be observed that Aristotle here resolves Definition into Genus and Differentiæ — ἐπειδὴ ὁ ὁρισμὸς ἐκ γένους καὶ διαφορῶν ἐστίν. Moreover, though he does not recognize Species as a separate head, yet in his definition of Genus he implies Species as known — γένος ἐστὶ τὸ κατὰ πλειόνων καὶ διαφερόντων τῷ εἴδει ἐν τῷ τί ἐστι κατηγορούμενον (p. 102, a. 31).

It thus appears that the quintuple classification is the real and logical one; but the quadruple may perhaps be more suitable for the Topica, with a view to dialectic procedure, since debates turn upon the attack and defence of a Definition.