I have found the following problem in a book:
Test the validity of the following argument: If 6 is not even, then 5 is not prime But 6 is even Therefore, 5 is prime
I have made a truth table by transforming it into logical propositions like: ~p -> ~q and p then q
and I end up with the values T/F/T/T
according to the answer of the book it is a fallacy. But logically seems that it is not, because 6 is even and 5 is a prime.
Is there any way to prove that this is a tautology?