CHA P. V.

Account of the remaining books of the
Organon.

IN

SECT. I. Of the Laft Analytics.

the First Analytics, fyllogifms are confidered in respect of their form; they are now to be confidered in respect 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.

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 premises are certain, and the conclufion drawn from them in due form, this is demonstration, and produces sciSuch fyllogifms are called apodic3 D 2

ence.

tical;

1

tical; and are handled in the two books of

the Laft Analytics. are not certain, but

When the premises probable only, fuch

fyllogifins are called dialectical; and of them he treats in the eight books of the Topics. 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 seem beautiful which is but painted. Thefe being apt to deceive, and produce a falfe opinion, are called fophiftical; and they are the subject of the book concerning Sophifms.

To return to the Laft Analytics, which treat of demonftration and of fcience: We fhall not pretend to abridge these 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 diftinctions, of which his genius was wonderfully productive.

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

can

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

We cannot demonftrate things in a circle, fupporting the conclufion by the premises, 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 necessary, general, and eternal truths: for of things fortuitous, contingent, or mutable, or of individual things, there is no demonstration.

Some demonftrations 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 muft be drawn from an immediate caufe; and are the most perfect.

The first figure is beft adapted to demonftration, 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 nega

1

tive; the demonstration of an univerfal to that of a particular; and direct demonstration 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

with regard

1. Whether the

the queftions that may be put
to any thing, are four:
thing be thus affected. 2. Why it is thus

affected.

3. Whether it exists. 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 defi-
nition 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 also of the four kinds of causes; efficient, material, formal, and final.

Another thing treated of in this book is,

the

the manner in which we acquire firft 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 Ariftotle, That there is nothing in the understanding which was not before in fome fense.

The knowledge of first principles, as it is not acquired by demonstration, 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 reason with probability and con

fiftency