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5. As

as in these, It rains, It snows. 2. In some propositions either term may be made the subject or the predicate as you like best; as in this, Virtue is the road to happiness. 3. The same example may serve to shew, that it is sometimes difficult to say, whether a proposition be universal or particular.

4. The quality of some propositions is so dubious, that logicians have never been able to agree whether they be affirmative or negative; as in this proposition, Whatever is insentient is not an animal. there is one class of propositions which have only two terms, to wit, one subject and one predicate, which are called categorical propositions ; so there are many classes that have more than two terms. What Aristotle delivers in this book is applicable only to categorical propofitions; and to them only the rules concerning the conversion of propositions, and concerning the figures and modes of fyllogisms, are accommodated. The subsequent writers of logic have taken notice of some of the many classes of complex propofitions, and have given rules adapted to them; but finding this work endless, they have left us to manage the rest by the rules of common sense,

CHAP

C Η Α Ρ.

III.

Account of the First Analytics,

Sect. 1. Of the Conversion of Propositions,

IN
N attempting to give some account of

the Analytics and of the Topics of Aristotle, ingenuity requires me to confess, that though I have often purposed to read the whole with care, and to understand what is intelligible, yet my courage and patience always failed before I had done. Why should I throw away so much time and painful attention upon a thing of so little real use? If I had lived in those

ages when the knowledge of Aristotle's Organon intitled a man to the highest rank in philosophy, ambition might have induced me to employ upon it fome years of painful study; and less, I conceive, would not be sufficient. Such reflections as these, always got the better of my resolution, when the first ardor began to cool. All I can say is, that I have read some parts of the different books with care, some slightly, and some perhaps not at all. I have glanced over the whole often, and when any thing attracted my attention, have dipped into it till my appetite was satisfied. Of all reading it is the most dry and the most painful, employing an infinite labour of demonstration, about things of the most abstract nature, delivered in a laconic style, and often, I think, with affected obscurity; and all to prove general propositions, which when applied to particular instances appear self-evident.

when years.

There is probably but little in the Categories or in the book of Interpretation, that Aristotle could claim as his own invention : but the whole theory of syllogisms he claims as his own, and as the fruit of much time and labour. And indeed it is a fiately fabric, a monument of a great genius, which we could wish to have been more usefully employed. There must be something however adapted to please the human understanding, or to flatter human pride, in a work which occupied men of speculation for more than a thousand

1

years. These books are called Analytics, because the intention of them is to resolve all reasoning into its simple ingredients.

The first book of the First Analytics, consisting of forty-six chapters, may be divided into four parts"; the first treating of the conversion of propositions ; the second, of the structure of syllogisms in all the different figures and modes; the third, of the invention of a middle term ; and the last, of the resolution of fyllogisms. We shall give a brief account of each.

To convert a proposition, is to infer from it another proposition, whose lubject is the predicate of the first, and whose predicate is the subject of the first. This is reduced by Aristotle to three rules. 1. An universal negative may be converted into an universal negative : thus, No man is a quadruped; therefore, No quadruped is a man. 2. An universal affirmative can be converted only into a particular affirmative: thus, All men are mortal; therefore, Some mortal beings are men. 3. A particular affirmative may be converted into a particular affirmative: as, Some men are just ; therefore, Some just persons are

When a proposition may be con-
VOL. III,

verted

men.

verted without changing its quantity, this is called simple conversion; but when the quantity is diminished, as in the universal affirmative, it is called conversion per accidens.

There is another kind of conversion, omitted in this place by Aristotle, but fupplied by his followers, called conversion by contraposition, in which the term that is contradictory to the predicate is put for the subject, and the quality of the proposition is changed; as, All animals are sentient; therefore, What is insentient is not an animal. A fourth rule of conversion therefore is, That an universal affirmative, and a particular negative, may be converted by contraposition.

SECT. 2. Of the Figures and Modes of pure

Syllogisms.

A syllogism is an argument, or reasoning, consisting of three propositions, the last of which, called the conclusion, is inferred from the two preceding, which are called the premises. The conclusion having two terms, a subject and a predicate, its

predicate

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