(1) “All roses are beautiful.”
(2) “None of the members of the stock exchange are dishonest.”
(3) “Some pupils are not industrious.”
(4) “Some teachers are tactful.”
(5a) Convert the following:
(1) “All that glitters is not gold.”
(2) “All good men are wise.”
(3) “Some books are to be chewed and digested.”
(4) “No man is perfectly happy.”
It is first necessary to determine the logical character of each proposition. Carelessness might lead one to call the first proposition an A because it is introduced by the quantity sign “all.” But on second thought we note that the meaning is to the effect that some glittering things are not gold; this is an O. It is clearthat the second is an A, the third an I and the fourth an E. It is now expedient to recall the rules regarding conversion. These are, (1) do not distribute an undistributed term; (2) do not change the quality. We may now attempt to interchange the subject and predicate of each proposition, with the following results: