The handling of sophistical and hypothetical arguments, and of those which derive their conclusions from questioning, and in a word the handling of all such arguments, relates to the duties of life, though the many do not know this truth. For in every matter we inquire how the wise and good man shall discover the proper path and the proper method of dealing with the matter. Let then people either say that the grave man will not descend into the contest of question and answer, or, that if he does descend into the contest, he will take no care about not conducting himself rashly or carelessly in questioning and answering. But if they do not allow either the one or the other of these things, they must admit that some inquiry ought to be made into those topics (τόπων) on which particularly questioning and answering are employed. For what is the end proposed in reasoning? To establish true propositions, to remove the false, to withhold assent from those which are not plain. Is it enough then to have learned only this? It is enough, a man may reply. Is it then also enough for a man, who would not make a mistake in the use of coined money, to have heard this precept: that he should receive the genuine drachmae and reject the spurious? It is not enough. What then ought to be added to this precept? What else than the faculty which proves and distinguishes the genuine and the spurious drachmae? Consequently also in reasoning what has been said is not enough; but it is necessary that a man should acquire the faculty of examining and distinguishing the true and the false, and that which is not plain? It is necessary. Besides this, what is proposed in reasoning? That you should accept what follows from that which you have properly granted. Well, is it then enough in this case also to know this? It is not enough; but a man must learn how one thing is a consequence of other things, and when one thing follows from one thing, and when it follows from several collectively. Consider then if it be not necessary that this power should also be acquired by him who purposes to conduct himself skillfully in reasoning, the power of demonstrating himself the several things which he has proposed, and the power of understanding the demonstrations of others, and of not being deceived by sophists, as if they were demonstrating. Therefore there has arisen among us the practice and exercise of conclusive arguments and figures, and it has been shown to be necessary.

But in fact in some cases we have properly granted the premises or assumptions, and there results from them something; and though it is not true, yet nonetheless it does result. What then ought I to do? Ought I to admit the falsehood? And how is that possible? Well, should I say that I did not properly grant that which we agreed upon? But you are not allowed to do even this. Shall I then say that the consequence does not arise through what has been conceded? But neither is this allowed. What then must be done in this case? Consider if it is not this: as to have borrowed is not enough to make a man still a debtor, but to this must be added the fact that he continues to owe the money and that the debt is not paid, so it is not enough to compel you to admit the inference that you have granted the premises (τὰ λήμματα), but you must abide by what you have granted. Indeed, if the premises continue to the end such as they were when they were granted, it is absolutely necessary for us to abide by what we have granted, and we must accept their consequences: but if the premises do not remain such as they were when they were granted, it is absolutely necessary for us also to withdraw from what we granted, and from accepting what does not follow from the words in which our concessions were made. For the inference is now not our inference, nor does it result with our assent, since we have withdrawn from the premises which we granted. We ought then both to examine such kinds of premises, and such change and variation of them (from one meaning to another), by which in the course of questioning or answering, or in making the syllogistic conclusion, or in any other such way, the premises undergo variations, and give occasion to the foolish to be confounded, if they do not see what conclusions (consequences) are. For what reason ought we to examine? In order that we may not in this matter be employed in an improper manner nor in a confused way.

And the same in hypotheses and hypothetical arguments; for it is necessary sometimes to demand the granting of some hypothesis as a kind of passage to the argument which follows. Must we then allow every hypothesis that is proposed, or not allow every one? And if not every one, which should we allow? And if a man has allowed a hypothesis, must he in every case abide by allowing it? or must he sometimes withdraw from it, but admit the consequences and not admit contradictions? Yes; but suppose that a man says, If you admit the hypothesis of a possibility, I will draw you to an impossibility. With such a person shall a man of sense refuse to enter into a contest, and avoid discussion and conversation with him? But what other man than the man of sense can use argumentation and is skillful in questioning and answering, and incapable of being cheated and deceived by false reasoning? And shall he enter into the contest, and yet not take care whether he shall engage in argument not rashly and not carelessly? And if he does not take care, how can he be such a man as we conceive him to be? But without some such exercise and preparation, can he maintain a continuous and consistent argument? Let them show this; and all these speculations (θεωρήματα) become superfluous, and are absurd and inconsistent with our notion of a good and serious man.

Why are we still indolent and negligent and sluggish, and why do we seek pretences for not laboring and not being watchful in cultivating our reason? If then I shall make a mistake in these matters may I not have killed my father? Slave, where was there a father in this matter that you could kill him? What then have you done? The only fault that was possible here is the fault which you have committed. This is the very remark which I made to Rufus when he blamed me for not having discovered the one thing omitted in a certain syllogism: I suppose, I said, that I have burnt the Capitol. Slave, he replied, was the thing omitted here the Capitol? Or are these the only crimes, to burn the Capitol and to kill your father? But for a man to use the appearances presented to him rashly and foolishly and carelessly, and not to understand argument, nor demonstration, nor sophism, nor, in a word, to see in questioning and answering what is consistent with that which we have granted or is not consistent; is there no error in this?