Institutio Oratoria

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

He who wishes to live a happy life, must be a philosopher

But all men wish to live a happy life,

That which is dissolved into its elements is devoid of feeling,

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,

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

You are illegitimate

You are not his only son

You are not his heir

The will is invalid

You are not entitled to inherit

You have co-heirs,

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.

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?

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?

What is the object of our escorts and our swords?

Which we certainly should not be permitted to have, if we were absolutely forbidden to use them.

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.

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

Because it brings us wealth,

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.