Imágenes de páginas
[ocr errors]

Let this ferve as a specimen of Aristotle's manner of treating the categories. After them, we have fome chapters, which the fchoolmen call poftprædicamenta; wherein first, the four kinds of opposition of terms are explained; to wit, relative, privative, of contrariety, and of contradiction. This is repeated in all fyftems of logic. Laft of all we have diftinctions of the four Greek words which answer to the Latin ones, prius, fimul, motus, and habere.

SECT. 4. Of the book concerning Interpretation.

We are to confider, fays Ariftotle, what a noun is, what a verb, what affirmation, what negation, what fpeech. Words are the figns of what paffeth in the mind; writing is the fign of words. The figns both of writing and of words are different in different nations, but the operations of mind fignified by them are the fame. There are some operations of thought which are neither true nor falfe. Thefe are expressed by nouns or verbs fingly, and without compofition.


A noun is a found which by compact fignifies fomething without respect to time, and of which no part has fignification by itself. The cries of beafts may have a natural fignification, but they are not nouns: we give that name only to founds which have their fignification by compact. The cafes of a noun, as the genitive, dative, are not nouns. Non homo is not a noun, but, for diftinction's fake, may be called a nomen infinitum.

[ocr errors]
[ocr errors]


A verb fignifies fomething by compact with relation to time. Thus valet is a verb; but valetudo is a noun, becaufe its fignification has no relation to time. It is only the prefent tenfe of the indicative that is properly called a verb; the other tenfes and moods are variations of the verb. Non valet may be called a verbum infinitum.

[ocr errors]

Speech is found fignificant by compact, of which fome part is alfo fignificant. And it is either enunciative, or not enunciative. Enunciative fpeech is that which affirms or denies. As to fpeech which is not enunciative, fuch as a prayer or wish, the confideration of it belongs to oratory, or poetry. Every enunciative fpeech must have


a verb, or fome variation of a verb. Affirmation is the enunciation of one thing concerning another. Negation is the enunciation of one thing from another. Contradiction is an affirmation and negation that are oppofite. This is a fummary of the first fix chapters.

The seventh and eighth treat of the va→ rious kinds of enunciations or propofitions, univerfal, particular, indefinite, and fingular; and of the various kinds of oppo→ fition in propofitions, and the axioms concerning them. These things are repeated in every fyftem of logic. In the ninth chapter he endeavours to prove by a long metaphyfical reafoning, that propofitions. respecting future contingencies are not, determinately, either true or false; and that if they were, it would follow, that all things happen neceffarily, and could not have been otherwife than as they are. The remaining chapters contain many minute obfervations concerning the equipollency of propofitions both pure and modal.




SECT. 1. On the Five Predicables.

HE writers on logic have borrowed


their materials almost entirely from Ariftotle's Organon, and Porphyry's Introduction. The Organon however was not written by Ariftotle as one work. It comprehends various tracts, written without the view of making them parts of one whole, and afterwards thrown together by his editors under one name on account of their affinity. Many of his books that are loft, would have made a part of the Organon if they had been faved.

The three treatifes of which we have given a brief account, are unconnected with each other, and with thofe that follow. And although the first was undoubtedly compiled by Porphyry and the two laft probably by Ariftotle, yet I confider VOL. III.

[ocr errors]


them as the venerable remains of a philofophy more ancient than Aristotle. Archytas of Tarentum, an eminent mathematician and philofopher of the Pythagorean school, is faid to have wrote upon the ten categories; and the five predicables probably had their origin in the fame school. Aristotle, though abundantly careful to do juftice to himself, does not claim the invention of either. And Porphyry, without afcribing the latter to Aristotle, professes only to deliver the doctrine of the ancients and chiefly of the Peripatetics, concerning them.

The writers on logic have divided that science into three parts; the first treating of fimple apprehension and of terms; the fecond, of judgement and of propositions; and the third, of reasoning and of fyllogifms. The materials of the first part are taken from Porphyry's Introduction and the Categories; and thofe of the fecond. from the book of Interpretation.

A predicable, according to the grammatical form of the word, might feem to fignify, whatever may be predicated, that is, affirmed or denied, of a fubject: and in that fenfe every predicate would be a predicable.

« AnteriorContinuar »