Prior Analytics - Book I   

Book I

1



WE must first state the subject of our inquiry and the faculty to

which it belongs: its subject is demonstration and the faculty that

carries it out demonstrative science. We must next define a premiss, a

term, and a syllogism, and the nature of a perfect and of an imperfect

syllogism; and after that, the inclusion or noninclusion of one term

in another as in a whole, and what we mean by predicating one term

of all, or none, of another.

A premiss then is a sentence affirming or denying one thing of

another. This is either universal or particular or indefinite. By

universal I mean the statement that something belongs to all or none

of something else; by particular that it belongs to some or not to

some or not to all; by indefinite that it does or does not belong,

without any mark to show whether it is universal or particular, e.g.

'contraries are subjects of the same science', or 'pleasure is not

good'. The demonstrative premiss differs from the dialectical, because

the demonstrative premiss is the assertion of one of two contradictory

statements (the demonstrator does not ask for his premiss, but lays it

down), whereas the dialectical premiss depends on the adversary's

choice between two contradictories. But this will make no difference

to the production of a syllogism in either case; for both the

demonstrator and the dialectician argue syllogistically after

stating that something does or does not belong to something else.

Therefore a syllogistic premiss without qualification will be an

affirmation or denial of something concerning something else in the

way we have described; it will be demonstrative, if it is true and

obtained through the first principles of its science; while a

dialectical premiss is the giving of a choice between two

contradictories, when a man is proceeding by question, but when he