While Hilary Putnam’s work on theories of meaning, semantic content, the nature of mental phenomena, interpretations of quantum mechanics, theory-change, logic, and mathematics is crucial to recent and future developments in philosophy, the scope and volume of his writings and his radical re-thinking of concepts make it challenging to portray his philosophy accurately. Maximilian de Gaynesford analyses Putnman’s complete works within their historical context. He argues that the work has a basic unity based on repeated engagement with a small set of hard problems and that understanding this unity helps make this influential philosopher accessible.