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 various kinds of enunciations or propofitions, univerfal, particular, indefinite, and fingular; and of the various kinds of oppofition 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 falfe; 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. CHAP. CHA P. II. Remarks. SECT. I. On the Five Predicables. THE writers on logic have borrowed their materials almoft entirely from Aristotle'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 treatises of which we have given a brief account, are unconnected with each other, and with those that follow. And although the first was undoubtedly compiled by Porphyry and the two laft probably by Ariftotle, yet I confider VOL. III, Sf them them as the venerable remains of a philofophy more ancient than Aristotle. Archytas of Tarentum, an eminent mathematician and philofopher of the Pythagorean fchool, is faid to have wrote upon the ten categories; and the five predicables probably had their origin in the fame fchool. Ariftotle, though abundantly careful to do juftice to himself, does not claim the invention of either. And Porphyry, without afcribing the latter to Ariftotle, profeffes only to deliver the doctrine of the ancients and chiefly of the Peripatetics, concerning them. The writers on logic have divided that fcience into three parts; the first treating of fimple apprehenfion and of terms; the fecond, of judgement and of propofitions; 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 second 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. predicable. But logicians give a different meaning to the word. They divide propofitions into certain claffes, according to the relation which the predicate of the propofition bears to the fubject. The first clafs is that wherein the predicate is the genus of the fubject; as when we say, This is a triangle, Jupiter is a planet. In the fecond clafs, the predicate is a Species of the fubject; as when we fay, This triangle is right-angled. A third clafs is when the predicate is the specific difference of the fubject; as when we fay, Every triangle has three fides and three angles. A fourth when the predicate is a property of the subject; as when we fay, The angles of every triangle are equal to two right angles. And a fifth clafs is when the predicate is fomething accidental to the fubject; as when we say, This triangle is neatly drawn. Each of these claffes comprehends a great variety of propofitions, having different fubjects, and different predicates; but in each clafs the relation between the predicate and the fubject is the fame. Now it is to this relation that logicians have given the name of a predicable. Hence it is, that although S f 2 although the number of predicates be infinite, yet the number of predicables can be no greater than that of the different relations which may be in propofitions between the predicate and the fubject. And if all propofitions belong to one or other of the five claffes above mentioned, there can be but five predicables, to wit, genus, Species, differentia, proprium, and accidens. These might, with more propriety perhaps, have been called the five claffes of predicates; but ufe has determined them to be called the five predicables. It may alfo be obferved, that as fome objects of thought are individuals, fuch as, Julius Cæfar, the city Rome; fo others are common to many individuals, as good, great, virtuous, vicious. Of this last kind are all the things that are expressed by adjectives. Things common to many individuals, were by the ancients called univerfals. All predicates are univerfals, for they have the nature of adjectives; and, on the other hand, all univerfals may be predicates. On this account, univerfals may be divided into the fame claffes as predicates; and as the five claffes of predicates above |