a tautology
a fallacy
equivalent to ¬p→q
equivalent to p→¬q
p | q | ¬p | p→q | ¬p→q | (¬p→q)→q | (p→q)→[(¬p→q)→q] |
---|---|---|---|---|---|---|
T | T | F | T | T | T | T |
T | F | F | F | T | F | T |
F | T | T | T | T | T | T |
F | F | T | T | F | T | T |
Since all the values in the last column are true, hence the given statement is a tautology.