For a tautology to work it always has to be true.
Sorry to butt in, but I think I might know where the confusion is coming from. Apart from its strictly logical meaning of "a statement that's always true", the word tautology is often used to mean repetition or circular circular reasoning (e.g. "I should join this honor society to show colleges I'm honorable, and I'm honorable because I'm in an honor society?").