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IN the firft Analytics, fyllogifms are confidered in respect of their formy they are now to be confidered in refpect of their matter. The form lies in the neceffary connection between the premises and the conclufion; and where fuch a connection is wanting, they are faid to be informal, or vicious in point of form. s.

But where there is no fault in the form, there may be in the matter; that is, in the propofitions of which they are compofed, which may be true or falfe, probable or improbable.

When the premifes are certain, and the conclufion drawn from them in due form, this is demonftration, and produces fcience. Such fyllogifms are called apodic


tical; and are handled in the two books of the Laft Analytics. When the premises are not certain, but probable only, fuch fyllogifms are called dialectical; and of them he treats in the eight books of the Topicks. But there are fome fyllogifms which feem to be perfect both in matter and form, when they are not really fo: as, a face may feem beautiful which is but painted. These being apt to deceive, and produce a false opinion, are called sophistical; and they are the fubject of the book concerning Sophifms.

To return to the Laft Analytics, which treat of demonftration and of fcience: We fhall not pretend to abridge thefe books; for Ariftotle's writings do not admit of abridgement: no man in fewer words can fay what he fays; and he is not often guilty of repetition. We fhall only give fome of his capital conclufions, omitting his long reafonings and nice distinctions, of which his genius was wonderfully productive.

All demonftration must be built upon principles already known; and these upon others of the fame kind; until we come at laft to firft principles, which neither

can be demonftrated, nor need to be, being evident of themselves.

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We cannot demonftrate things in a circle, fupporting the conclufion by the premifes, and the premises by the conclufion. Nor can there be an infinite number of middle terms between the first principle and the conclufion.

In all demonstration, the first principles, the conclufion, and all the intermediate propofitions, must be neceffary, general, and eternal truths: for of things fortuitous, contingent, or mutable, or of individual things, there is no demonstration.

Some demonstrations prove only, that the thing is thus affected; others prove, why it is thus affected. The former may be drawn from a remote caufe, or from an effect: but the latter must be drawn from an immediate caufe; and are the most perfect.

The first figure is beft adapted to demonstration, because it affords conclufions univerfally affirmative; and this figure is commonly used by the mathematicians.

The demonftration of an affirmative propofition is preferable to that of a negaVOL. III. 3 D


tive; the demonstration of an univerfal to that of a particular; and direct demonftration to that ad abfurdum.

The principles are more certain than the conclufion.

There cannot be opinion and science of the fame thing at the fame time.

In the fecond book we are taught, that the questions that may be put with regard to any thing, are four: 1. Whether the thing be thus affected. 2. Why it is thus affected. 3. Whether it exifts. 4. What it is.

The last of these questions Aristotle, in good Greek, calls the What is it of a thing. The schoolmen, in very barbarous Latin, called this, the quiddity of a thing. This quiddity, he proves by many arguments, cannot be demonftrated, but must be fixed by a definition. This gives occafion to treat of definition, and how a right definition fhould be formed. As an example, he gives a definition of the number three, and defines it to be the first odd number.

In this book he treats alfo of the four kinds of caufes; efficient, material, formal, and final.

Another thing treated of in this book is,


the manner in which we acquire first principles, which are the foundation of all demonstration. These are not innate, because we may be for a great part of life ignorant of them: nor can they be deduced demonstratively from any antecedent knowledge, otherwife they would not be first principles. Therefore he concludes, that first principles are got by induction, from the informations of fenfe. The fenfes give us informations of individual things, and from these by induction we draw general conclufions: for it is a maxim with Aristotle, That there is nothing in the underftanding which was not before in fome fenfe.

The knowledge of firft principles, as it is not acquired by demonftration, ought not to be called fcience; and therefore he calls it intelligence.

SECT. 2. Of the Topics.

The profeffed defign of the Topics is, to fhew a method by which a man may be able to reafon with probability and confiftency

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