But a simple conclusion is reprehended if that which follows does not appear of necessity to cohere with that which has gone before. For this very proposition, "If he breathes, he is alive," "If it is day, it is light," is a proposition of such a nature that the latter statement appears of necessity to cohere with the preceding one. But this inference, "If she is his mother, she loves him," "If he has ever done wrong, he will never be chastised," ought to be reprehended in such a manner as to show that the latter proposition does not of necessity cohere with the former.
Inferences of this kind, and all other unavoidable conclusions, and indeed all argumentation whatever, and its reprehension too, contains some greater power and has a more extensive operation than is here explained. But the knowledge of this system is such that it cannot be added to any portion of this art, not that it does of itself separately stand in need of a long time, and of deep and arduous consideration. Wherefore those things shall be explained by us at another time, and when we are dealing with another subject, if opportunity be afforded us. At present we ought to be contented with these precepts of the rhetoricians given for the use of orators. When, therefore, any one of these points which are assumed is not granted, the whole statement is invalidated by these means.
XLVII. But when, though these things are admitted, a conclusion is not derived from them, we must consider these points too, whether any other conclusion is obtained, or whether anything else is meant, in this way,—If, when any one says that he is gone to the army, and any one chooses to use this mode of arguing against him, "If you had come to the army you would have been seen by the military tribunes, but you were not seen by them, therefore you did not go to the army." On this case, when you have admitted the proposition, and the assumption, you have got to invalidate the conclusion, for some other inference has been drawn, and not the one which was inevitable.
And at present, indeed, in order that the case might be more easily understood, we have brought forward an example pregnant with a manifest and an enormous error; but it often happens that an error when stated obscurely is taken for a truth; when either you do not recollect exactly what admissions you have made, or perhaps you have granted something as certain which is extremely doubtful. If you have granted something which is doubtful on that side of the question which you yourself understand, then if the adversary should wish to adapt that part to the other part by means of inference, it will be desirable to show, not from the admission which you have made, but from what he has assumed, that an inference is really established; in this manner:—"If you are in need of money, you have not got money. If you have not got money, you are poor. But you are in need of money, for if it were not so you would not pay attention to commerce; therefore you are poor." This is refuted in this way:—"When you said, if you are in need of money you have not got money, I understood you to mean, 'If you are in need of money from poverty, then you have not got money;' and therefore I admitted the argument. But when you assumed, 'But you are in need of money,' I understood you to mean, 'But you wish to have more money.' But from these admissions this result, 'Therefore you are poor,' does not follow. But it would follow if I had made this admission to you in the first instance, that any one who wished to have more money, had no money at all."
XLVIII. But many often think that you have forgotten what admissions you made, and therefore an inference which does not follow legitimately is introduced into the summing up as if it did follow; in this way:—"If the inheritance came to him, it is probable that he was murdered by him." Then they prove this at considerable length. Afterwards they assume, But the inheritance did come to him. Then the inference is deduced; Therefore he did murder him. But that does not necessarily follow from what they had assumed. Wherefore it is necessary to take great care to notice both what is assumed, and what necessarily follows from those assumptions. But the whole description of argumentation will be proved to be faulty on these accounts; if either there is any defect in the argumentation itself, or if it is not adapted to the original intention. And there will be a defect in the argumentation itself, if the whole of it is entirely false, or common, or ordinary, or trifling, or made up of remote suppositions; if the definition contained in it be faulty, if it be controverted, if it be too evident, if it be one which is not admitted, or discreditable, or objected to, or contrary, or inconstant, or adverse to one's object.
That is false in which there is evidently a lie; in this manner:—"That man cannot be wise who neglects money. But Socrates neglected money; therefore he was not wise." That is common which does not make more in favour of our adversaries than of ourselves; in this manner:—"Therefore, O judges, I have summed up in a few words, because I had truth on my side." That is ordinary which, if the admission be now made, can be transferred also to some other case which is not easily proved; in this manner:—"If he had not truth on his side, O judges, he would never have risked committing himself to your decision." That is trifling which is either uttered after the proposition, in this way:—"If it had occurred to him, he would not have done so;" or if a man wishes to conceal a matter manifestly disgraceful under a trifling defence, in this manner:—
"Then when all sought your favour, when your hand
Wielded a mighty sceptre, I forsook you;
But now when all fly from you, I prepare
Alone, despising danger, to restore you."
XLIX. That is remote which is sought to a superfluous extent, in this manner:—"But if Publius Scipio had not given his daughter Cornelia in marriage to Tiberius Gracchus, and if he had not had the two Gracchi by her, such terrible seditions would never have arisen. So that all this distress appears attributable to Scipio." And like this is that celebrated complaint—
"Oh that the woodman's axe had spared the pine
That long on Pelion's lofty summit grew."[57]
For the cause is sought further back than is at all necessary. That is a bad definition, when it either describes common things in this manner:—"He is seditious who is a bad and useless citizen;" for this does not describe the character of a seditious man more than of an ambitious one,—of a calumniator, than of any wicked man whatever, in short. Or when it says anything which is false; in this manner:—"Wisdom is a knowledge how to acquire money." Or when it contains something which is neither dignified nor important; in this way:—"Folly is a desire of inordinate glory." That, indeed, is one folly; but this is defining folly by a species, not by its whole genus. It is controvertible when a doubtful cause is alleged, for the sake of proving a doubtful point; in this manner:—