Page:O. F. Owen's Organon of Aristotle Vol. 1 (1853).djvu/218

 premise by conversion, for it is always subverted through the third figure, but we must assume both propositions to the minor term, likewise also if the syllogism is negative. For let A be shown through B to be present with no C, wherefore if A is assumed present with every C, but with no B, B will be with no C, and if A and B are with every C, A will be with a certain B, but it was present with none.

If however the conclusion is converted contradictorily, the (other) syllogisms also will be contradictory, and not universal, for one premise is particular, so that the conclusion will be particular. For let the syllogism be affirmative, and be thus converted, hence if A is not with every C, but with every B, B will not be with every C, and if A is not with every C, but B with every C, A will not be with every B. Likewise, if the syllogism be negative, for if A is with a certain C, but with no B, B will not be with a certain C, and not simply with no C, and if A is with a certain C, and B with every C, as was assumed at first, A will be with a certain B.

In particular syllogisms, when the conclusion is converted contradictorily, both propositions are subverted, but when contrarily, neither of them; for it no longer happens, as with universals, that through failure of the conclusion by conversion, a subversion is produced, since neither can we subvert it at all. For let A be demonstrated of a certain C, if therefore A is assumed present with no C, but B with a certain C, A will not be with a certain B, and if A