C as true, but the whole of A B as false, and that A is with every B, it is impossible for the conclusion to be true, for it was present with no C, since A was present with none of what B was present with, but B was with every C.
In like manner also the conclusion will be false, if A is with every B, and B with every C, and the proposition B C is assumed true, but A B wholly false, and that A is present with no individual with which B is, for A will be with every C, since with whatever B is, A also is, but B is with every C. It is clear then, that, the major premise being assumed wholly false, whether it be affirmative or negative, but the other premise being true, there is not a true conclusion; if however the whole is not assumed false, there will be. For if A is with every C, but with a certain B, and B is with every C; e.g. animal with every swan, but with a certain whiteness, and whiteness with every swan, if A is assumed present with every B, and B with every C, A will also be truly present with every C, since every swan is an animal.
So also if A B be negative, for A concurs with a certain B, but with no C, and B with every C, as animal with something white, but with no snow, and whiteness with all snow; if then A is assumed present with no B, but B with every C, A will be present with no C.
If however the proposition A B were assumed wholly true, but B C wholly false, there will be a true syllogism, as nothing prevents A from being with every B and every C, and yet B with no C, as is the case with species of the same genus, which
