Category Archives: Ancient Greek Philosophy

Knowledge of Animal Kinds is an Empirical, not a Logical, Enterprise

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As Aristotle proceeds in his criticism of division (Parts of Animals 642b ff.), he indirectly illuminates a methodological point about how the ‘branches’ of the tree of the division are supposed to work.  When we have a given animal before us, we first might determine what it has: feet.  Thus we have some first genus (footed) from which we can have differentiae.  These differentiae might be two-footed and four-footed, as in his example.

What this shows is that this process is empirically based on two counts.  The first is that  the divider is aware of a given animal in both what it possesses and what it is.  Secondly, there is a contextual awareness of the animals that are alike, in some way, to this animal.  In other words, the would-be divider knows that there are no one-footed or 563-footed animals.  How does he know this?  By experience.

There might even be an allowance on Aristotle’s part that there is a kind of wisdom of the crowd in understanding animal divisions.  He says that the “bird and the fish are named,” but adds that others “are nameless, such as the blooded and unblooded [animal] (642b14-15).  If this is so, it is reasonable to believe that Greeks, from Aristotle’s perspective, have got it right with regards to birds and fish due to generations of people having seen various birds and fish.  There is thus a kind of group empirical gathering of facts.

This emphasis on the actual is also why, it turns out, that Aristotle says there can be no privations in divisions.  “And yet it is necessary to divide by privation and the dichotomists do divide by privation. But there is no difference of privation qua privation: it is impossible for there to be a species of something that does not exist, such as footless or wingless in the same way there is of winged and footed” (PA 642b21-24 Greek follows below).  This is another indication that for Aristotle, a proper division is always empirically based, since one cannot go out and find footless animals.  What he means by this is that the animal will not have “footless” as part of its definition or essence.  Now of course, a slug, for example, is without feet, but it is also without feathers, and this hardly seems worthy of being remarked upon, much less to make it an opportunity for division.  Thus another way of stating why to exclude privation: whatever privation we choose to divide by certainly is vulnerable to the charge of being arbitrary.  For every animal is deprived of many attributes and features.

Ἔτι στερήσει μὲν ἀναγκαῖον διαιρεῖν, καὶ διαιροῦσιν οἱ
διχοτομοῦντες. Οὐκ ἔστι δὲ διαφορὰ στερήσεως ᾗ στέρησις· ἀ-
δύνατον γὰρ εἴδη εἶναι τοῦ μὴ ὄντος, οἷον τῆς ἀποδίας ἢ τοῦ
ἀπτέρου ὥσπερ πτερώσεως καὶ ποδῶν. (PA 642b21-24)

Problems with Plato: Animal Diversity and Robust Division

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Yesterday, I brought up some difficulties that occur in the first method of division presented in Aristotle’s Parts of Animals.

“Some construe the individual species by dividing the group into two differentiae.  In one way this is not easy, in another impossible.  For of some there will be only one differentia, but the other terms will be superfluous, such as in the case of footed, two-footed, footed with parted toes.  For this last differentia alone is proper” (Parts of Animals, 642b5-9)?

Before discussing the difficulties again, it must be taken into consideration, of course, that since he is embarking on a criticism of Academic methodology, any philosophical difficulties arising from this process of division might in fact owe to chinks in the armor which Aristotle himself was trying to illuminate.  He might very well be bringing some of these difficulties to light without proceeding to explain them.

A couple of the difficulties I brought up yesterday were:

“It is not true that the concept of “footed with parted toes” includes “two footed” and “footed.” viz. lizards

It is also clear from his use of the term elsewhere, that “footed with parted toes (σχιζόπους)” is not meant to designate any particular species alone, such as humans (cf. HA 593a28, concerning birds).”

A mistake one could make, at least in Aristotle’s construal of the division, is failing to recognize that at every point of the division a particular animal is being guided through each step of the division.  So, in this example, one has to have in mind a particular animal which one leads through each “gate” of the division.  There is no abstracted “two-footed,” in other words; differentiae always belong to real animals.  (This is one reason why Aristotle says shortly that there cannot be divisions of non-being, for no animals correspond to such a division.)

In fact, Aristotle will return to this division at 643b29 ff.  He says there two interesting things.  He affirms that with this method both (a) that only one differentia will be arrived at (b) it is impossible for one differentia to be adequate for a species.  In light of this he brings up the same “footed, two-footed, footed with parted toes,” tri-partite division.  Only this time he applies it to “man” (ἄνθρωπος).  He points out that man is many other things besides possessing parted toes.

Both of these judgments merge into a single criticism: there is a need for there to be multiple differentia, although the Academic method cannot allow for it, it is not so much wrong, as it is inadequate.  One reason for a need for more lines of division is that there are many homologous features in animals.  Similar body plans, parts, and functions means that there will be many animals with split-toed feet.  Because of this diversity there will be a corresponding need for a robust method of division.

Parts of Animals: Dividing Feet, Divided Opinions

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“Some construe the individual species by dividing the group into two differentiae.  In one way this is not easy, in another impossible.  For of some there will be only one differentia, but the other terms will be superfluous, such as in the case of footed, two-footed, footed with parted toes.  For this last differentia alone is proper.”
(Aristotle, Parts of Animals, 642b5-9 Greek follows below)

This begins that section of the Parts of Animals concerning a critique of the Platonic method of division, here namely in light of animal divisions.  This initial critique begins with bifurcation, that is, division of animals into X or not-X.  (This is meant to include not only antinomies, i.e. winged and wingless, but also opposites such as black and white, as well as other empirically inducted differences.)  Since this small passage kicks off the discussion, it would desirable to obtain some clarity about it. Exampling this method, by taking the X route, Aristotle proceeds from “footed,” leaving “non-footed” to the side.  He then further divides “footed” into “two-footed” and “footed with parted toes.”  “Footed with parted toes” is said to be proper or valid (κυρία).  This presumably means that the terms “footed” and “two-footed” are unnecessary, as they are included in the concept of “footed with parted toes.”  This is what Aristotle means by “some terms being superfluous (περίεργα).”

However a number of problems remain:
It is not true that the concept of “footed with parted toes” includes “two footed” and “footed.” viz. lizards

It is also clear from his use of the term elsewhere, that “footed with parted toes (σχιζόπους)” is not meant to designate any particular species alone, such as humans (cf. HA 593a28, concerning birds).

Perhaps this introductory polemic is intended by Aristotle to conjure up the Academic chestnut that man is a featherless biped, showing here, of course, both how absurd that notion is and its genesis in a faulty method of division. (See Statemans 266e for the origin of the featherless biped.)

Λαμβάνουσι δ’ ἔνιοι τὸ καθ’ ἕκαστον, διαιρούμενοι τὸ (5)
γένος εἰς δύο διαφοράς. Τοῦτο δ’ ἐστὶ τῇ μὲν οὐ ῥᾴδιον, τῇ δὲ
ἀδύνατον. Ἐνίων γὰρ ἔσται διαφορὰ μία μόνη, τὰ δ’ ἄλλα
περίεργα, οἷον ὑπόπουν, δίπουν, σχιζόπουν· αὕτη γὰρ
μόνη κυρία. Εἰ δὲ μή, ταὐτὸν πολλάκις ἀναγκαῖον λέγειν.