Well, from a logic standpoint, in mathmatics we have the four "types" of negation:
1. If A, then B.
2. If B, then A.
3. If not A, then not B.
4. If not B, then not A.
1 and 4 always have the same truth value for any hypothesis. 2 and 3 also always have the same truth value. However 1 and 2...