 As we have seen, this criterion was present in the Tractatus (6.211), but noticeably absent in the middle period. The reason for this absence is probably that the intermediate Wittgenstein wanted to stress that in mathematics everything is syntax and nothing is meaning. Hence, in his criticisms of Hilbert’s ‘contentual’ mathematics (Hilbert 1925) and Brouwer’s reliance upon intuition to determine the meaningful content of (especially undecidable) mathematical propositions, Wittgenstein couched his finitistic constructivism in strong formalism, emphasizing that a mathematical calculus does not need an extra-mathematical application (PR §109; WVC 105).