Charles Sanders Peirce (1839-1914) was the greatest American philosopher of the 19th century and the founder of philosophical pragmatism. He is best known for his distinctive conception of philosophical method (his ‘pragmatic maxim’, a rule for the clarification of ‘intellectual concepts’, reflecting his highly original theory of meaning), his ‘semeiotic’ or theory of signs, his conception of truth as indefeasible belief, and his profound contributions to philosophical logic. He is also known for anticipating numerous significant developments in philosophy and other disciplines, many of them only fully realized long after his death. Sometimes dubbed ‘the American Aristotle’, he was “a prolific and perpetually over-extended polymath” (Crease), the scale of whose work is staggering and virtually impossible to summarize. Even today, Peirce’s work has yet enjoy a fraction of the attention or recognition it deserves. There are numerous reasons for this: his work is often extremely technical, his papers were left in disarray for decades after his death, and the majority of them remain unpublished; he also had a fraught, scandal-ridden career. He died ‘in abject poverty and almost completely forgotten’ (de Waal). Interest in and appreciation for Peirce has only grown in recent decades, however, and Peirce scholarship is an unusually lively field in the history of philosophy.