Page:O. F. Owen's Organon of Aristotle Vol. 1 (1853).djvu/219

 is with no C, but with every B, B will be with no C, so that both propositions are subverted. If however the conclusion be converted contrarily, neither (is subverted), for if A is not with a certain C, but with every B, B will not be with a certain C, but the original proposition is not yet subverted, for it may be present with a certain one, and not present with a certain one. Of the universal proposition A B there is not any syllogism at all, for if A is not with a certain C, but is with a certain B, neither premise is universal. So also if the syllogism be negative, for if A should be assumed present with every C, both are subverted, but if with a certain C, neither; the demonstration however is the same.

Chapter 9
the second figure we cannot subvert the major premise contrarily, whichever way the conversion is made, since the conclusion will always be in the third figure, but there was not in this figure an universal syllogism. The other proposition indeed we shall subvert similarly to the conversion, I mean by similarly, if the conversion is made contrarily (we shall subvert it contrarily), but if contradictorily by contradiction, For let A be with every B and with no C, the conclusion B C, if then B is assumed present with every C, and the proposition A B remains, A will be with every C, for there is the first figure. If however B is with every C, but A with no C, A is not with every B, the last figure. If then B C (the conclusion) be converted contradictorily, A B may be demonstrated similarly, and A C contradictorily. For if B is with a certain C, but A with no C, A will not be present with a certain B; again, if B is with a certain C, but A