Discussion
The first two methods of proof,the “Trivial Proof” and the “Vacuous Proof”, are certainly the eadiest when they work. Notice that the from of the “Trivial Proof”,
q → ( p → q ),is,in fact, a tautology. This follows from disjunction introduction,since p → q is equivalent to ~p ∨q. Likewise,the “Vacuous Proof”is based on the tautology ~p → ( p → q ).