NOTE.—The first proposition is poetical while the second is an exclusive.
(6a) Contravert the following propositions:
(1) “All virtue is praiseworthy.”
(2) “Some teachers are not tactful.”
(3) “A man who lies is not to be trusted.”
Contraversion consists in obverting first, and then converting; consequently, the contraverse of the three propositions is as follows:
(1) “No unpraiseworthy deed is virtue.”
(2) “Some not-tactful persons are teachers.”
(3) “Some untrustworthy men are those who lie.”
(6b) Write the contraverse of the following: