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?