front 1 Modus ponens | back 1 If A, then B. A. So, B. |
front 2 Modus tollens | back 2 If A, then B. Not B. So, not A. |
front 3 Hypothetical syllogism | back 3 If A, then B. If B, then C. So, if A then C. |
front 4 Disjunctive syllogism | back 4 Either A or B. Not A. So, B.
|
front 5 Constructive dilemma | back 5 Either A or B. If A, then C. If B, then D. So, either C or D. |