Again, the term difference is applied in cases when the genus is divided into species and one species is subdivided. Animal, for instance, is a genus, mortal a species, while terrestrial or biped is a difference: for they are not actually properties, but serve to show the difference between such animals and quadrupeds or creatures of the sea. This distinction, however, comes under the province not so much of argument as of exact definition. Cicero Cic. Top. iii. 13. separates genus and species,

which latter he calls form, from definition and includes them under relation. For example, if a person to whom another man has left all his silver should claim all his silver money as well, he would base his claim upon genus; on the other hand if when a legacy has been left to a married woman holding the position of materfamilias, it should be maintained that the legacy is not due to a woman who never came into the power of her husband, the argument is based on species, since there are two kinds of marriage. There was the formal marriage per coemptionem, bringing the woman under the power ( in manum )of her husband and giving her the title of materfamilias, and the informal marriage based on cohabitation without involving the wife's coming in manum mariti. Cicero Cic. Top.

further shows that definition is assisted by division, which he distinguishes from partition, making the latter the dissection of a whole into its parts and the former the division of a genus into its forms or species. The number of parts he regards as being uncertain, as for instance the elements of which a state consists; the forms or species are, however, certain, as for instance the number of forms of government, which we are told are three, democracy, oligarchy, and monarchy. It is true that he does not use these illustrations,

since, as he was writing to Trebatius, A famous lawyer, cp. III. xi. 18. v. 17. he preferred to draw his examples from law. I have chosen my illustrations as being more obvious. Properties have relation to questions of fact as well; for instance, it is the property of a good man to act rightly, of an angry man to be violent in speech or action, and consequently we believe that such acts are committed by persons of the appropriate character, or not committed by persons of inappropriate character. For just as certain persons possess certain qualities, so certain others do not possess certain qualities, and the argument is of precisely the same nature, though from opposite premises.

In a similar way division is valuable both for proof and refutation. For proof, it is sometimes enough to establish one thing. To be a citizen, a man must either have been born or made such. For refutation, both points must be disproved: he was neither born nor made a citizen.

This may be done in many ways, and constitutes a form of argument by elimination, whereby we show sometimes that the whole is false, sometimes that only that which remains alter the process of elimination is true. An example of the first of these two cases would be: You say that you lent him money. Either you possessed it yourself, received it from another, found it or stole it. If you did not possess it, receive it from another, find or steal it, you did not lend it to him.

The residue after elimination is shown to be true as follows: This slave whom you claim was either born in your house or bought or given you or left you by will or captured from the enemy or belongs to another. By the elimination of the previous suppositions he is shown to belong to another. This form of argument is risky and must be employed with care; for if, in setting forth the alternatives, we chance to omit one, our whole case will fail, and our audience will be moved to laughter. It is safer to do what Cicero pro Caec. xiii. 37.

does in the pro Caecina, when he asks, If this is not the point at issue, what is? For thus all other points are eliminated at one swoop. Or again two contrary propositions may be advanced, either of which if established would suffice to prove the case. Take the following example from Cicero: pro Cluent. xxiii. 64. There can be no one so hostile to Cluentius as not to grant me one thing: if it be a fact that the verdict then given was the result of bribery, the bribes must have proceeded either from Habitus or Oppianicus: if I show that they did not proceed from Habitus I prove that they proceeded from Oppianicus: if I demonstrate that they were given by Oppianicus, I clear Habitus.

Or we may give our opponent the choice between two alternatives of which one must necessarily be true, and as a result, whichever he chooses, lie will damage his case. Cicero does this in the pro Oppio: Oppius was accused of embezzling public money and plotting against the life of M. Aurelius Cotta, governor of Bithynia, where Oppius was serving as quaestor. Cicero's defence of him is lost. Was the weapon snatched from his hands when he had attacked Cotta, or when he was trying to commit suicide? and in the pro Vareno: See iv. ii. 26. You have a choice between two alternatives: either you must show that the choice of this route by Varenus was due to chance or that it was the result of this man's persuasion and inducement. He then shows that either admission tells against his opponent. Sometimes again,

two propositions are stated of such a character that the admission of either involves the same conclusion, as in the sentence, We must philosophise, even though we ought not, or as in the common dilemma, What is the use of a figure, See vii. iv. 28, ix. i. 14, ix. ii. 65. if its meaning is clear? And what is its use, if it is unintelligible? or, He who is capable of enduring pain will lie if tortured, and so will he who cannot endure pain.

As there are three divisions of time, so the order of events falls into three stages. For everything has a beginning, growth and consummation, as for instance a quarrel, blows, murder. Thus arise arguments which lend each other mutual support; for the conclusion is inferred from the beginnings, as in the following case: I cannot expect a purple-striped toga, when I see that the beginning of the web is black ; or the beginning may be inferred from the conclusion: for instance the fact that Sulla resigned the dictatorship is an argument that Sulla did not take up arms with the intention of establishing a tyranny.

Similarly from the growth of a situation we may infer either its beginning or its end, not only in questions of fact but as regards points of equity, such as whether the conclusion is referable to the beginning, that is, Should the man that began the quarrel be regarded as guilty of the bloodshed with which it ended? Arguments are also drawn from similarities:

If self-control is a virtue, abstinence is also a virtue.If a guardian should be required to be faithful to his trust, so should an agent. To this class belongs the type of argument called ἐπαγωγή by the Greeks, induction by Cicero. de Inv. i. 31. Or arguments may be drawn from unlikes: It does not follow that if joy is a good thing, pleasure also is a good thing : It does not follow that what applies to the case of a woman applies also to the case of a ward. Or from contraries: Frugality is a good thing, since luxury is an evil thing : If war is the cause of ill, peace will prove a remedy : If he who does harm unwittingly deserves pardon, he who does good unwittingly does not deserve a reward.

Or from contradictions: He who is wise is not a fool. Or from consequences necessary or probable It is possible that Quintilian regards adiuncta as = consequentia. The distinction made above is that made by Cicero, Top. xii. : If justice is a good thing, we must give right judgment : If breach of faith is a bad thing, we must not deceive. And such arguments may also be reversed. Similar to these are the following arguments, which must therefore be classed under this same head, since it is to this that they naturally belong: A man has not lost what he never had : A man does not wittingly injure him whom he loves : If one man has appointed another as his heir, he regarded, still regards and will continue to regard him with affection. However, such arguments, being incontrovertible, are of the nature of absolute indications. See ch. ix.

These, however, I call consequent or ἀκόλουθα goodness, for instance, is consequent on wisdom: while in regard to things which merely have taken place afterwards or will take place I use the term insequent or παρεπόμενα, though I do not regard the question of terminology as important. Give them any name you please, as long as the meaning is clear and it is shown that the one depends on time, the other on the nature of things.

I have therefore no hesitation in calling the following forms of argument also consequential, although they argue from the past to the future: some however divide them into two classes, those concerned with action, as in the pro Oppio, How could he detain against their will those whom he was unable to take to the province against their will? and those concerned with time, as in the Verrines, Verr. I. xlii. 109. The praetor on entering office on Jan. I issued an edict announcing the principles on which his rulings would be given. This edict was an interpretation of the law of Rome, and held good only during the praetor's year of office. If the first of January puts an end to the authority of the praetor's edict, why should the commencement of its authority not likewise date from the first of January?

Both these instances are of such a nature that the argument is reversible. For it is a necessary consequence that those who could not be taken to the province against their will could not be retained against their will.

So too I feel clear that we should rank as consequential arguments those derived from facts which lend each other mutual support and are by some regarded as forming a separate kind of argument, which they Ar. Rhet. II. xxiii. 3. call ἐκ τῶν πρὸς ἄλληλα, arguments from things mutually related, while Cicero de Inv. I. xxx. 46. styles them arguments drawn from things to which the same line of reasoning applies; take the following example ib. 47. : If it is honourable for the Rhodians to let out their harbour dues, it is honourable likewise for Hermocreon to take the contract, or What it is honourable to learn, it is also honourable to teach. Such also is the fine sentence of Domitius Afer,

which has the same effect, though it is not identical in form: I accused, you condemned. Arguments which prove the same thing from opposites are also mutually consequential; for instance, we may argue that he who says that the world was created thereby implies that it is suffering decay, since this is the property of all created things.

There is another very similar form of argument, which consists in the inference of facts from their efficient causes or the reverse, a process known as argument from causes. The conclusion is sometimes necessary, sometimes generally without being necessarily true. For instance, a body casts a shadow in the light, and the shadow wherever it falls indicates the presence of a body.