A man must be orthodox upon most things, or he will never even have time to preach his own heresy.
-- G. K. Chesterton
Quoted by John Holbo, at CT, where (in comment #13) Jim Harrison adds:
Rhetoric, after all, has always been about making the worse case defeat the better.
But (of course) I wholly misunderstand (you remember my definition of misunderstand) rhetoric.