Imágenes de páginas
[ocr errors]

Let this serve as a specimen of Aristotle's manner of treating the categories. After them, we have some chapters, which the schoolmen call postprædicamenta'; 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 systems of logic. Last of all we have distinctions of the four Greek words which answer to the Latin ones, prius, fimul, motus, and habere.

Sect. 4. Of the book concerning Interpre: tation,

We are to consider, says Aristotle, what a noun is, what a verb, what affirmation, what negation, what speech. Words are the signs of what passeth in the mind; writing is the sign of words. The signs both of writing and of words are different in different nations, but the operations of mind signified by them are the same. There are some operations of thought which are neither true nor false. Thefe are expressed by nouns or verbs singly, and without composition,


[ocr errors]

A noun is a found which by compact fignifies fomething without respect to time, and of which no part has signification by itself. The cries of beasts may have a natural fignification, but they are not nouns: we give that name only to sounds which have their fignification by compact. The cases 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. -A verb fignifies fomething by compact with relation to time. Thus valet is a verb; but valetudo is a noun, because its fignification has no relation to time. It is only the prefent tense 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.

Speech is found significant by compact, of which some part is also significant. And it is either enunciațive, or not enunciative. Enunciative speech is that which affirms or denies. As to speech which is not enunciative, such as a prayer or wish, the consideration of it belongs to oratory, or poetry. Every enunciative speech must have

[merged small][ocr errors]

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 opposite. This is a summary of the first six chapters.

The seventh and eighth treat of the various kinds of enunciations or propofitions; universal, particular, indefinite, and fingular; and of the various kinds of oppofition in propofitions, and the axioms concerning them. These chings are repeated in every fystem of logic. In the ninth chapter he endeavours to prove by a long metaphyGical reasoning, that propofitions respecting future contingencies are noc, determinately, either true or false; and that if they were, it would follow, that all things happen necessarily, and could not have been otherwise than as they arë. The remaining chapters contain many minute obfervations concerning the equipollency of propositions both pure and modal.




SECT. I. On the Five Predicablesó

HE writers on logic have borrowed

their materials almost entirely from Aristotle's Organon, and Porphyry's Introduction. The Organon however was not written by Aristotle 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 lost, would have made a part of the Organon if they had been faved.

The three treatises of which we have given a brief account, are unconnected with each other, and with those that follow. And although the first was undoubeedly. compiled by Porphyry and the two last probably by Aristotle, yet I consider VOL. III.



them as the venerable remains of a philofophy more ancient than Aristotle. Archytas of Tarentum, an eminent mathematician and philosopher of the Pythagorean school, is said 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 justice 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 simple apprehension and of terms; the second, of judgement and of propositions; and the third, of reasoning and of syllogisms. The materials of the first part are taken from Porphyry's Introduction and the Categories; and those of the second. from the book of Interpretation.

A predicable, according to the grammatical form of the word, might seem to fignify, whatever may be predicated, that is, affirmed or denied, of a subject; and in that sense every predicate would be a


« AnteriorContinuar »