 Wittgenstein takes the same data and, in a way, draws the opposite conclusion. If, as Brouwer says, we are uncertain whether all or some “mathematical problems” are solvable, then we know that we do not have in hand an applicable decision procedure, which means that the alleged mathematical propositions are not decidable, here and now. “What ‘mathematical questions’ share with genuine questions”, Wittgenstein says (PR §151), “is simply that they can be answered”. This means that if we do not know how to decide an expression, then we do not know how to make it either proved (true) or refuted (false), which means that the Law of the Excluded Middle “doesn’t apply” and, therefore, that our expression is not a mathematical proposition.