If we show that a claim is equivalent to a tautology (which is stronger than showing the claim implies a tautology), how come that isn't a valid method of proof?
How come proof by tautology is not acceptable?
1
$\begingroup$
logic
proof-writing
-
2Showing that the claim implies a tautology doesn't tell you anything, since a tautology should be true anyhow. It *is* sufficient to show that your claim follows from a tautology, so if you show that your claim is equivalent to a tautology, you have shown that it is true. – 2012-11-04
-
0What text or class did this come from? – 2012-11-04