Institutio Oratoria

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

v4-6 p.243

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.)