Before revision: The only thing that can justify P is another statement – let's call it P1; so P1 justifies P. But if P1 is to be a satisfactory justification for P, then we must know that P1 .
After revision: is trueThe only thing that can justify P is another statement – let's call it P1; so P1 justifies P. But if P1 is to be a satisfactory justification for P, then we must know that P1 .