Chapter 10
In the first place then, let us define what is a dialectic proposition, and what a dialectic problem, for we must not suppose every proposition nor every problem as dialectic, since no one in his senses would propose that which is assented to by no one, nor would he advance as a question what was palpable to all, or to most men, for the latter does not admit of a doubt, but the former no one would admit. Indeed a dialectic proposition is an interrogation, probable either to all, or to the most, or to the wise; and to these, either to all or most, or to the most celebrated, it is not paradoxical, as any one may admit what is assented to by the wise, if it be not contrary to the opinions of the multitude. Dialectic propositions however are both those which resemble the probable and which are contrary to those which appear probable, being proposed through contradiction, and whatever opinions are according to the discovered arts. For if it be probable that there is the same science of contraries, it would also appear probable that the sense of contraries is the same, and if the grammatical art be one in number, that there is one art also of playing on the pipe, but if there are many grammatical arts, there will also be many piping arts, for all these things seem to be similar and akin. So also those things which are contrary to probabilities, being proposed according to contradiction, will appear probable, for if it is probable that we ought to benefit friends, it is also probable that we ought not to injure them. Nevertheless, that we ought to injure friends is contrary, but that we ought not to injure them is contradictory; so also if we ought to benefit friends, we ought not to benefit enemies; but this also is according to the contradiction of contraries, since the contrary is that we ought to benefit enemies, and in like man-
