Institutio Oratoria

Quintilian

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

This major premise is either an admitted fact as in the last example or requires

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to be proved as in the following:
He who wishes to live a happy life, must be a philosopher
: for this is not an acknowledged truth, and the premises must be established before we can arrive at the conclusion. Sometimes again the minor premise is an admitted fact, as for instance,
But all men wish to live a happy life,
while sometimes it requires to be proved, as for example the statement quoted above,
That which is dissolved into its elements is devoid of feeling,
since it is doubtful whether the soul is immortal after its release from the body or only continues to exist for a time. Some call this a minor premise, some a reason.

There is no difference between the epicheireme and the syllogism, except that the latter has a number of forms and infers truth from truth, whereas the epicheireme is frequently concerned with statements that are no more than credible. For if it were always possible to prove controversial points from admitted premises, the orator would have little to do in this connexion.

For what skill does it require to say,

The property is mine, for I am the only son of the deceased,
or
I am the sole heir, since possession of the testator's estate is given by the law of property in accordance with the terms of his will: the property therefore belongs to me
?

But when the reason given is itself disputable, we must establish the certainty of the premises by which we are proposing to prove what is uncertain. For example, if our opponent says

You are not his son
or
You are illegitimate
or
You are not his only son
; or, again,
You are not his heir
or
The will is invalid
or
You are not entitled to inherit
or
You have co-heirs,
we must prove the validity
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of the reason on which we base our claim that the property should be adjudicated to us.

But when a reason of unusual length intervenes, it is necessary to state the final conclusion, otherwise the major premise and the reason would suffice.

Laws are silent in the midst of arms, and do not require us to await their sanction when the circumstances are such that he who would await their sanction is certain to be the victim of an unjust penalty before ever the just penalty can be claimed.
[*](pro Mil. iv. 10. ) Hence it has been asserted that the form of enthymeme which is based on denial of consequents resembles a reason. But sometimes, again, it is sufficient to state a single proposition as in the example just quoted,
The laws are silent in the midst of arms.

We may also begin with the reason and then proceed to the conclusion as in another passage from the same speech [*](ib. iii. 9. ) :

But if the Twelve Tables permitted the killing of a thief by night under any circumstances, and by day if he used a weapon to defend himself, who is there who will contend that the slayer must be punished under whatever circumstances a man has been killed?
'The process is still further varied by Cicero, and the reason placed third, as in the phrase,
When he sees that the sword is sometimes placed in our hands by the laws themselves.

On the other hand, he places the various parts in the regular order in the following instance:

How can it be unjust to kill a robber who lies in wait for his victim?
[*](ib. iv. 10. ) Next comes the reason:
What is the object of our escorts and our swords?
Last comes the conclusion resulting from the major premise and the reason:
Which we certainly should not be permitted to have, if we were absolutely forbidden to use them.
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This form of proof may be countered in three ways, that is to say it may be attacked in all its parts. For either the major premise or the minor or the conclusion or occasionally all three are refuted. The major premise is refuted in the following case:

I was justified in killing him, as he lay in wait for me.
For the very first question in the defence of Milo is
whether it is right that he who confesses that he has killed a man should look upon the light of day.

The minor premise is refuted by all the methods which we mentioned in dealing with refutation. [*](In the preceding chapter.) As to the reason it must be pointed out that it is sometimes true when the proposition to which it is attached is not true, but may on the other hand sometimes be false although the proposition is true. For example,

Virtue is a good thing
is true, but if the reason,
Because it brings us wealth,
be added, we shall have an instance of a true major premise and a false reason.

With regard to the conclusion, we may either deny its truth when it infers something which does not logically result from the premises, or we may treat it as irrelevant. The truth is denied in the following case:

We are justified in killing one who lies in wait for us; for since, like an enemy, he threatens us with violence, we ought to repulse his attack as though he were an enemy: therefore Milo was justified in killing Clodius as an enemy.
The conclusion is not valid, since we have not yet proved that Clodius lay in wait for him But the conclusion that we are therefore justified in killing one who lies in wait for us is perfectly true, though irrelevant to the case, for it is not yet clear that Clodius lay in wait for Milo.