Institutio Oratoria

Quintilian

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

The following is an example of a syllogism:

Virtue is the only thing that is good, for that alone is good which no one can put to a bad use: but no one can make a bad use of virtue; virtue therefore is good.
The enthymeme draws its conclusion from denial of consequents.
Virtue is a good thing because no one can put it to a bad use.
On the other hand take the following syllogism.
Money is not a good thing; for that is not good which can be put to a bad use: money may be put to a bad use; therefore money is not a good thing.
The enthymeme draws its conclusion from incompatibles.
Can money be a good thing when it is possible to put it to a bad use?

The following argument is couched in syllogistic form:

If money in the form of silver coin is silver, the man who bequeathed all his silver to a legatee, includes all money in the form of coined silver: but he bequeathed all his silver: therefore he included in the bequest all money in the form of coined silver.
But for the orator it will be sufficient to say,
Since he bequeathed all his silver, he included in his bequest all his silver money.

I think I have now dealt with all the precepts of those who treat oratory as a mystery. But these rules still leave scope for free exercise of the judgment. For although I consider that there are occasions

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when the orator may lawfully employ the syllogism, I am far from desiring him to make his whole speech consist of or even be crowded with a mass of epicheiremes and enthymemes. For a speech of that character would resemble dialogues and dialectical controversies rather than pleadings of the kind with which we are concerned, and there is an enormous difference between the two.

For in the former we are confronted with learned men seeking for truth among men of learning; consequently they subject everything to a minute and scrupulous inquiry with a view to arriving at clear and convincing truths, and they claim for themselves the tasks of invention and judgment, calling the former τοπική or the art of selecting the appropriate material for treatment, and the latter κριτική or the art of criticism.