 Łukasiewicz criticises Aristotle for on the one hand claiming PC cannot be proved, and on the other hand attempting an indirect or pragmatic “proof”. In partial agreement with the tradition according to which PC is not the cornerstone or basic principle of logic, Łukasiewicz claims that its status is less secure than some other logical propositions, and that its function is principally to serve as a pragmatic norm. Nevertheless, in an Appendix to the book he gives a formal derivation of one version of PC from other assumptions. This shows that PC is as it were just one logical theorem among others, a statement that would raise few eyebrows today but was fairly radical in its day. Among the assumptions used in the derivation is a version of the Principle of Bivalence, that every proposition is either true or false and none is both, so the derivation of PC is not after all such a surprise.