Institutio Oratoria

Quintilian

Quintilian. Institutio Oratoria, Volume 1-4. Butler, Harold Edgeworth, translator. Cambridge, Mass; London: Harvard University Press, William Heinemann Ltd., 1920-1922.

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.

There are other conclusions which, as I have said, are not necessary, whether as regards both cause and effect or only one of the two. For instance,

the sun colours the skin, but not
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everyone that is coloured receives that colour from the sun; a journey makes the traveller dusty, but every journey does not produce dust, nor is everyone that is dusty just come from a journey.

As examples of necessary conclusions on the other hand I may cite the following:

If wisdom makes a man good, a good man must needs be wise
; and again,
It is the part of a good man to act honourably, of a bad man to act dishonourably,
or
Those who act honourably are considered good, those who act dishonourably are considered bad men.
In these cases the conclusion is correct. On the other hand,
though exercise generally makes the body robust, not everyone who is robust is given to exercise, nor is everyone that is addicted to exercise robust. Nor again, because courage prevents our fearing death, is every man who has no fear of death to be regarded as a brave man; nor is the sun useless to man because it sometimes gives him a headache.

Arguments such as the following belong in the main to the hortative department of oratory:—

Virtue brings renown, therefore it should be pursued; but the pursuit of pleasure brings ill-repute, therefore it should be shunned.
But the warning that we should not necessarily search for the originating cause is just: an example of such error is provided by the speech of Medea [*]( The opening of Ennius' translation of the Medea of Euripides. ) beginning

Ah! would that never there in Pelion's grove,
as though her misery or guilt were due to the fact that there
  1. The beams of fir had fallen to the ground
    ;
or I might cite the words addressed by Philoctetes to Paris, [*]( From the Philoctetes of Accius, Ribbeck fr. 178. )
  1. Hadst thou been other than thou art, then I
  2. Had ne'er been plunged in woe.
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By tracing back causes on lines such as these we may arrive anywhere.

But for the fact that Cicero [*](Top. iii. 12. ) has done so, I should regard it as absurd to add to these what is styled the conjugate argument, such as

Those who perform a just act, act justly,
a self-evident fact requiring no proof; or again,
Every man has a common right to send his cattle to graze in a common pasture.

Some call these arguments derived from causes or efficients by the Greek name ἐκβάσεις that is, results; for in such cases the only point considered is how one thing results from another. Those arguments which prove the lesser from the greater or the greater from the less or equals from equals are styled apposite or comparative.

A conjecture as to a fact is confirmed by argument from something greater in the following sentence:

If a man commit sacrilege, he will also commit theft
; from something less, in a sentence such as
He who lies easily and openly will commit perjury
; from something equal in a sentence such as
He who has taken a bribe to give a false verdict will take a bribe to give false witness.

Points of law may be proved in a similar manner; from something greater, as in the sentence

If it is lawful to kill an adulterer, it is lawful to scourge him
; from something less,
If it is lawful to kill a man attempting theft by night, how much more lawful is it to kill one who attempts robbery with violence
; from something equal,
The penalty which is just in the case of parricide is also just in the case of matricide.
In all these cases we follow the syllogistic method. [*](See III. vi. 15, 43, 88.)

The following type of argument on the other hand is more serviceable in questions turning

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on definition or quality. [*]( See iii. 6. passim. )
If strength is good for the body, health is no less good.
If theft is a crime, sacrilege is a greater crime.
If abstinence is a virtue, so is self-control.
If the world is governed by providence, the state also requires a government.
If a house cannot be built without a plan, what of a whole city?
If naval stores require careful supervision, so also do arms.

I am content to treat this type of argument as a genus without going further; others however divide it into species. For we may argue from several things to one or from one thing to several; hence arguments such as

What has happened once may happen often.
We may also argue from a part to a whole, from genus to species, from that which contains to that which is contained, from the difficult to the easy, from the remote to the near, and similarly from the opposites of all these to their opposites.

Now all these arguments deal with the greater or the less or else with things that are equal, and if we follow up such fine distinctions, there will be no limit to our division into species. For the comparison of things is infinite; things may be more pleasant, more serious, more necessary, more honourable, more useful. I say no more for fear of falling into that very garrulity which I deprecate.

The number of examples of these arguments which I might quote is likewise infinite, but I will only deal with a very few. As an example of argument from something greater take the following example from the pro Caecina [*](XV. 43.)

Shall we suppose that that which alarms whole armies caused no alarm to a peaceful company of lawyers?
As an instance of argument from something easier, take this passage
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from the speech against Clodius and Curio: [*]( A lost speech of Cicero to which reference is made in III. vii. 2. )
Consider whether it would have been easy for you to secure the praetorship, when he in whose favour you withdrew failed to secure election?