Institutio Oratoria
Quintilian
Quintilian. Institutio Oratoria, Volume 1-4. Butler, Harold Edgeworth, translator. Cambridge, Mass; London: Harvard University Press, William Heinemann Ltd., 1920-1922.
Again, it requires no skill to rebut arguments which are obviously contradictory, superfluous or foolish, and consequently I need give no examples nor instructions as to the method to be employed. There is also the type of charge which is known as obscure, where it is alleged that an act was committed in secret without witnesses or any evidence to prove it: this suffers from an inherent weakness, since the fact that our opponent can produce no proof is sufficient for our purpose: the same applies to arguments which are irrelevant to the case.
It is, however, sometimes an orator's duty to make it appear that some argument of his opponent is contradictory or irrelevant or incredible or superfluous or really favourable to his own client. Oppius [*](cp. § 21 and v. x 69. ) is charged with having embezzled the supplies intended to feed the troops. It is a serious charge, but Cicero shows that it contradicts other charges, since the same accusers also charged Oppius with desiring to corrupt the army by bribes.
The accuser of Cornelius offers to produce witnesses to show that he read out the law when tribune [*](cp. IV. ii. 13. ) : Cicero makes this argument