Institutio Oratoria

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

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.