On Sophistical Refutations   

it was better to take a walk after dinner, because of Zeno's argument,

would not be a proper argument for a doctor, because Zeno's argument

is of general application. If, then, the relation of the contentious

argument to the dialectical were exactly like that of the drawer of

false diagrams to the geometrician, a contentious argument upon the

aforesaid subjects could not have existed. But, as it is, the

dialectical argument is not concerned with any definite kind of being,

nor does it show anything, nor is it even an argument such as we

find in the general philosophy of being. For all beings are not

contained in any one kind, nor, if they were, could they possibly fall

under the same principles. Accordingly, no art that is a method of

showing the nature of anything proceeds by asking questions: for it

does not permit a man to grant whichever he likes of the two

alternatives in the question: for they will not both of them yield a

proof. Dialectic, on the other hand, does proceed by questioning,

whereas if it were concerned to show things, it would have refrained

from putting questions, even if not about everything, at least about

the first principles and the special principles that apply to the

particular subject in hand. For suppose the answerer not to grant

these, it would then no longer have had any grounds from which to

argue any longer against the objection. Dialectic is at the same

time a mode of examination as well. For neither is the art of

examination an accomplishment of the same kind as geometry, but one

which a man may possess, even though he has not knowledge. For it is

possible even for one without knowledge to hold an examination of

one who is without knowledge, if also the latter grants him points

taken not from thing that he knows or from the special principles of

the subject under discussion but from all that range of consequences

attaching to the subject which a man may indeed know without knowing

the theory of the subject, but which if he do not know, he is bound to

be ignorant of the theory. So then clearly the art of examining does

not consist in knowledge of any definite subject. For this reason,