At Categories 7, 6a36-7 Aristotle defines relatives (R1), but at 8a13-28 worries that the definition may include some substances. Aristotle introduces a second account of relatives (R2, at 8a31-2) to solve the problem. Recent commentators have held that Aristotle intends to solve the extensional adequacy worry by restricting the extension of relatives. That is, R2 counts fewer items as relative than R1. However, this cannot explain Aristotle’s attitude to relatives, since he immediately returns to using R1. I propose a non-extensional reading. R1 and R2 do not specify different sets of relatives, but rather different ways to understand each relative.
Although Caujolle-Zaslawsky1980, 188denies this. She holds that R1 gives only a necessary condition of being a relative, but her position is untenable. R1 is said by Aristotle to be a definition, so, at a minimum, Aristotle must intend R1 to give necessary and sufficient conditions for being a relative.
Mignucci1986, 107-8; Bodéüs 2001, 129-30; Sedley 2002, 332-3. Possibly also Harari 2011, 535 who, despite attempting to preserve the unity of the category of relatives, states that R2 has a narrower scope than R1. This view also had ancient adherents, especially those who think R1 is Platonic in some important sense: see Simplicius, in Cat. 159.9-22 Kalbfleisch.
Mignucci1986, 101-7; Morales 1994, 250; Bodéüs 2001, 129; Sedley 2002, 332; Harari 2011, 535. Ackrill 1963, 101 avoids committing himself by calling the what we find at 8a33-5 a ‘criterion’.
Mignucci1986, 107misses this point, and asserts that R2 is strictly narrower than R1. Ackrill 1963, 101 is more cautious, committing himself only to the claim that ‘whatever satisfies the second criterion also satisfies the first’. Cf. Topics 1.5, 101b37-102a31, where Aristotle distinguishes ‘definition’ from ‘unique property’. These two have the same extension—they pick out all and only items that fall under a term—but definition picks out the essence, while ‘unique property’ does not.
For a range of worries, see Ackrill1963, 103; Mignucci 1986, 109; Morales 1994, 263; Bodéüs 2001, 131-2.
Ackrill1963, 102mentions, but does not endorse this move. He says that, if we endorse the move, we owe an explanation of why the same move cannot be made in the case of ‘hand’: such an explanation is precisely what I have given here. If ‘hand’ is understood specifically, then there is no way to know hand definitely.