C.  F. Since, then, you have divided the topics to give credit to an oration into confirmation and reprehension, and since you have fully discussed the one, explain to me now the subject of reprehension.

C.  P. You must either deny the whole of what the adversary has assumed in argumentation, if you can show it to be fictitious or false, or you must refute what he has assumed as probable.  First of all, you must urge that he has taken what is doubtful as if it were certain; in the next place, that the very same things might be said in cases which were evidently false; and lastly, that these things which he has assumed do not produce the consequences which he wishes to be inferred from them.  And you must attack his details, and by that means break down his whole argument.  Instances also must be brought forward which were overruled in a similar discussion; and you must wind up with the complaints of the condition of the general danger, if the life of innocent men is exposed to the ingenuity of men devoted to calumny.

XIII. C.  F. Since I know now whence arguments can be derived which have a tendency to create belief, I am waiting to hear how they are severally to be handled in speaking.

C.  P. You seem to be inquiring about argumentation, and as to how to develop arguments.

C.  F. That is the very thing that I want to know.

C.  P. The development, then, of an argument is argumentation; and that is when you assume things which are either certain or at least probable, from which to derive a conclusion, which taken by itself is doubtful, or at all events not very probable.  But there are two kinds of arguing, one of which aims directly at creating belief, the other principally looks to exciting such and such feelings.  It goes straight on when it has proposed to itself something to prove, and assumed grounds on which it may depend; and when these have been established, it comes back to its original proposition, and concludes.  But the other kind of argumentation, proceeding as it were backwards and in an inverse way, first of all assumes what it chooses, and confirms it; and then, having excited the minds of the hearers, it throws on to the end that which was its original object.  But there is this variety, and a distinction which is not disagreeable in arguing, as when we ask something ourselves, or put questions, or express some command, or some wish, as all these figures are a kind of embellishment to an oration.  But we shall be able to avoid too much sameness, if we do not always begin with the proposition which we desire to establish, and if we do not confirm each separate point by dwelling on it separately, and if we are at times very brief in our explanation of what is sufficiently clear, and if we do not consider it at all times necessary to sum up and enumerate what results from these premises when it is sufficiently clear.

XIV. C.  F. What comes next?  Is there any way or any respect in which those things which are said to be devoid of art, and which you said just now were accessories to the main argument, require art?