 In his second book, The Laws of Thought, Boole not only applied algebraic methods to traditional logic but also attempted some reforms to logic. He started by augmenting the laws of his 1847 algebra of logic (without explicitly saying that his previous list of three axioms was inadequate), and made some comments on the rule of inference (performing the same operation on both sides of an equation). But then he casually stated that the foundation of his system actually rested on a single (new) principle, namely it sufficed to check an argument by seeing if it was correct when the class symbols took on only the values 0 and 1, and the operations were the usual arithmetical operations. Let us call this Boole’s Rule of 0 and 1. No meaningful justification was given for Boole’s adoption of this new foundation, it was not given a special name, and the scant references to it in the rest of the book were usually rather clumsily stated. For a modern analysis of this Rule of 0 and 1 see Burris &amp; Sankappanavar 2013.