We Cannot Have Miscalculated in 12 Times 12 Equals 144

Fraga: If you could be mistaken about the hand, you might be mistaken about every other statement about physical objects. So the whole structure crumbles, you have nothing against which you can check. This is like what I was talking about in the more episodes with global versus local error, right? There's no way to know about local error. You undermine that very concept. Fraga: The ultimate grounds for believing involve the actual rules of the game and practice. We got to know the nature of calculating by learning to calculate.