"Just for argument's sake" (again)(again)

"Was I fooling myself? I know myself to be a man skilled in self-deception, and so maybe (for the sake of argument, for the sake of whatever truth may be in argument) I ought to suppose that I was fooling myself."
~Jayber Crow, Wendell Berry

I just thought that second way was, perhaps, a better answer, the truest and rightest reason we can have for argument.