Aristóteles sobre el método platónico de la división // Division and Essence. Aristotle?s Criticism and Use of Platonic Division

FABIAN MIE

SANTA FE

Jornada; XIV Jornadas de Comunicación de Investigación en Filosofía; 2018

Universidad Nacional del Litoral

Aristotle rejected division as a weak deduction (Prior Analytics I 31, 46a33), since, according to him, division begs the question by always deducing something higher or more general than the attribute to be demonstrated (46a33-34). Aristotle's hard criticism is not independent from his own theory of deduction and of science. He sees division as a rival for his theory of deduction, and so he objects against Plato?s divisions both that they do not know what can be deduced, and that the ?deduction according to division? cannot really proceed in the way the Platonists make it proceed.Let us take a look at Aristotle?s more formal criticism against division. He claims that the essence cannot be proved, implying therewith that the Platonic division aims at deducing or demonstrating the essence. This is a topic Aristotle elaborates further in APo. II 5-10. In APr. I 31, 46a39ff., Aristotle attacks the formal failures of division. One main attack is against the non-necessary relation between the (syllogistic) terms of a division: in division, every A is either B or C; then it assumes that A belongs to D (?man is animal?); the deduction (in division) is that every A will be either B or C. So that, every man (D), which is assumed to be animal, i.e. A, is necessary B or C (mortal or immortal). But, that D is B (?man in mortal?) is not necessary (not deduced by necessity), but only asked for. This is though what we need to deduce (i.e. to demonstrate, in Aristotelian terms) (see 46b26-37, where Aristotle claims that division considers only the alternative ?either footed or footless?, so that the necessity in the deduction reaches only to the alternative; see the further elaboration of this attack in APo. II 5, 91b12-27). Putting aside any discussion about the possible different epistemological frameworks in which the account of essence of Plato and Aristotle are embedded, I would like to consider briefly the aforementioned question about the efficacy of division for finding out the essential parts of a kind. Aristotle does not grant to division such an efficacy. He argues that being forced to assume the alternative (either footed or footless), whatever option you choose will be arbitrary, and even if you choose the right option, that will remain unproved. This is not solved, for Aristotle, by dividing in just a few or many steps. Finally, if the steps of a division lack any necessity, nothing prevents adding or subtracting terms. It could be surprising that after such a devastating criticism, Aristotle goes on to accept that if we follow some recommendations, which basically coincide with those given by Plato, and even though division will never be a deduction properly, it will permit us to know the essence (91b33-35). I cannot discuss at length here the following two striking lines, but it may be worth quoting now: It is possible to solve the difficulties if you assume everything in what the thing is, make the division consecutive by postulating what is primitive, and leave nothing out (APo. II 5, 91b29-30). I hold that the recommendations for division contained here are four, and none of them is ignored by Plato: (i) assume every term in what the thing is (λαμβάνειν ἐν τῷ τί ἐστι πάντα) (i.e. every term must be essential to the definiendum or part of its essence); (ii) divide in order or consecutively (καὶ τὸ ἐφεξῆς τῇ διαιρέσει ποιεῖν) (i.e. one term must come after the other in a series); (iii) postulate what comes first (αἰτούμενον τὸ πρῶτον) (i.e. identify the genus and, perhaps, what is prior at each cut); (iv) do not leave something out (μηδὲν παραλείπειν) (i.e. include all the essential features). I hold that these and other similar advices given by Aristotle (see 96a24ff.) come quite close to those already made by Plato in the passages on diairesis. Furthermore, what Aristotle?s critical remarks can offer us is a characterization of what a Platonic division really amounts to. This characterization is given at the outset of Aristotle?s positive revision of division in Posterior Analytics II 13. There, he makes the basic but important claim that division is for hunting out the items or real parts predicated in the essence (θηρεύειν τὰ ἐν τῷ τί ἐστι κατηγορούμενα, 96a22-23; see also De Partibus Animalium I 3, 643a27).I would like to discuss here Aristotle?s attitude towards Platonic division in order to find out why, after having criticized division, he can still hold that division is a useful procedure for grasping the essence. If it is true that Aristotle grants the method such a performance and result, I would like to see a bit more clear which are the Aristotelian improvements that could allow him to put that method in practice for his own epistemological goals. My presentation will be very basic and a preliminary to discussion; I aim mainly to focus myself on the relevant texts. To begin with, I will present Plato?s description of division (and its counterpart procedure, i.e. collection); afterwards I go through some relevant Aristotelian texts (beginning with the Analytics and then moving to the De Partibus Animalium) in which we can find out his differentiated attitude towards division. My limited aim here is not to set the issue, but rather to make a first approach for a further discussion.