Later Greek Logic

LATER GREEK LOGIC After Aristotle we have, as regards logic, what the verdict of after times has rightly characterized as an age of Epigoni. So far as the Aristotelian framework is accepted we meet only minor corrections and extensions of a formal kind. If there is conscious and purposed divergence from Aristotle, enquiry moves, on the whole, within the circle of ideas where Aristotelianism had fought its fight and won its victory. Where new conceptions emerge, the imperfection of the instruments, mechanical and method ological, of the sciences renders them unfruitful until their re discovery in a later age. We have activity without diversity without development. Attempts at end in the compromises of eclecticism.

The Stoics

are of some importance. Despite the fact that their philosophic interests lay rather in ethics and physics, their activity in what they classified as the third department of speculation was enormous and has at least left ineffaceable traces on the terminology of philosophy. Logic is their word, and consciousness, impression and other technical words come to us, at least as technical words, from Roman stoicism. Even inference, though apparently not a classical word, throws back to the Stoic name for a conclusion.

Another doctrine of the Stoics which has interest in the light of certain modern developments is their insistence on the place of the XEKTOP in knowledge. Distinct alike from thing and mental happening, it seems to correspond to "meaning." Along the same lines is their use of the hypothetical form for the uni versal judgment, and their treatment of the hypothetical form as the typical form of inference.

The Stoical categories, too, have an historical significance. They are apparently offered in place of those of Aristotle, an acquaintance with whose distinctions they clearly presume. Rec ognizing a linguistic side to "logical" theory with a natural de velopment in rhetoric, the Stoics endeavour to exorcise consider ations of language from the contrasted side. They offer pure categories arising in series, each successive one pre-supposing those that have gone before. Yet the substance, quality, condition ab solute r(.7)s gxoy and condition relative of Stoicism have no en during influence outside the school, though they recur with eclectics like Galen.

Epicureans.

In falling back upon the atomism of Democritus, Epicurus had to face some questions of logic. In the inference

from phenomena to further phenomena positive verification must be insisted on. In the inference from phenomena to their non phenomenal causes, the atoms, with their inaccessibility to sense, a different canon of validity obtains, that of non-contradiction. He distinguishes, too, between the inference to combinations of atoms as universal cause, and inference to special causes beyond the range of sense. In the latter case alternatives may be ac quiesced in. The practical aim of science is as well achieved if we set forth possible causes as in showing the actual cause. More probably it reflects the fact that Epicurus was, on the whole, dominated by the influences that produced Pyrrhonism.

Sceptics.

The school of Pyrrho has exercised a more legit imate influence. The major premise of syllogism, says the Pyrrhonist, is established inductively from the particular in stances. If there be but one of these uncovered by the generaliza tion, this cannot be sound. If the crocodile moves its upper, not its lower jaw, we may not say that all animals move the lower jaw. The conclusion then is really used to establish the major premise, and if we still will infer it therefrom we fall into the circular proof. Could Mill say more? But again. The inductive enumeration is either of all cases or of some only. The former is in an indeterminate or infinite subject-matter impossible. The latter is invalid.

Neo-Platonists.----In

the history of logic Neo-platonism is of importance because of its production of a whole series of com mentators on the Aristotelian logic. Not only the Introduction of Porphyry, which had lasting effects on the Scholastic tradition, but the commentaries of Themistius and Simplicius. It was the acceptance of the Aristotelian logic by Neo-platonism that de termined the Aristotelian complexion as the logic of the next age. If Alexander is responsible for such doctrines as that of the intellectus acquisitus, it is to Porphyry, with his characteristically Platonist preference for the doctrine of universals, and for classi fication, that we owe the scholastic preoccupation with the realist controversy, and with the quinque votes, i.e., the Aristotelian predicables as restated by Porphyry.