Principles A and B were proposed within Government and Binding framework (Chomsky 1981), as governing rules on the distribution of anaphors and pronouns, respectively. Previous analyses explained the motivations behind these rules as following from locality-based grammatical constraints, or, alternatively, as a result of discourse pressures involving speaker expectation and competition between forms. We integrate data from historical linguistics, recent experimental evidence, and modern corpus surveys to show that the binding principles cannot be reduced to expectation and competition but rather have to make reference to syntactic structure.