In the treatise of Categories, after enumerating the ten categories in Chapter IV, Aristotle undertakes to examine each of the principle four in a separate Chapter. On the first reading, it seems difficult to understand Aristotle's goal in this detailed study. The unity of the inquiry is not really evident: Aristotle tests certain criteria (contrariety, a more and a less, simultaneity) for each category. Nevertheless, when we more closely compare the structure and the results of Chapters V, VI, VII, and VIII, we can put forward an idea of Aristotle's aim and propose an interpretation in which he would look for determining a distinctive character (idion) of all items that belong to one and the same category and of them only.
Indeed, Chapters V and VI both end in the same way: Aristotle concludes with what is most distinctive of substance and quantity, respectively being "numerically one and the same [and being] able to receive contraries" (4b17) and "being called both equal and unequal" (6a35). To the contrary, at the end of Chapter VII, instead of the statement of relatives' distinctive character that we would expect there, we are faced with a puzzled and perplexed conclusion that we can understand as a confession of failure. Aristotle refuses to make a peremptory (sphodrôs) ruling on the questions that touch relatives without having reexamined them. Thus, he does not offer what is the most distinctive of relatives. In this regard, the category appears as an exception, although Chapter VIII represents a return to the normal case, except that the determination of quality's idion ("being called similar and dissimilar" 11a18-19) does not close the Chapter. Aristotle continues with a discussion of the way in which certain things seem to fall at the same time into the category of relatives and into that of quality. According to Caujolle-Zaslawsky , it is precisely because Aristotle does not identify what is the most distinctive of relatives that he does not master this category and see it extending beyond quality. We shall study this point in our third section. Nonetheless, for three of the four categories that are examined in detail, Aristotle determines what is their distinctive character, and for two of them, closes with that. And as a confession of perplexity concludes Chapter VII, we can see here a clue towards the hypothesis that in these Chapters, Aristotle does aim to determine an idion that would permit the discrimination of all items included in a category and of them only.
Since, for relatives, Aristotle's undertaking ends with a confession of failure, this paper proposes to clarify what relatives are by examining the obstacles that stand in the way of determining a distinctive character. We shall wonder why Aristotle is not satisfied with any tested criterion. And insofar as we do not have relatives' idion, we shall look for something that permits one to identify relatives anyway despite their tendency to extend beyond other categories. In this regard, we shall also discuss the problem of overlapping.
1.First difficulty : The immediate diversity of relatives
a. The plural designation of the category
The first obstacle encountered in the investigation of what is properly distinctive of relatives is the heterogeneousness of items falling into this category, which straightaway appears much less unified than the other ones. First, the way Aristotle names the category of relatives (ta pros ti) contrasts with the general designations of substance (hê ousia), quantity (to poson) and quality (hê poiotês or to poion). Indeed, although other categories are designated by a singular substantive, ta pros ti' is in the plural and corresponds to the substantivization of a prepositional syntagm. To this prepositional character, we can compare the use, as substantives too, of to poson'and to poion' which usually...