Numbers and politics are inter-related at almost every level - be it the abstract geometry of understandings of territory, the explosion of population statistics and measures of economic standards, the popularity of Utilitarianism, Rawlsian notions of justice, the notion of value, or simply the very idea of political science. This book engages with the relation between politics and number through a reading, exegesis and critique of the work of Martin Heidegger. The importance of mathematics and the role played by the understandings of calculation is a recurrent concern in his writing and is regularly contrasted with understandings of speech and language. This book provides the most detailed analysis of the relation between language, politics and mathematics in Heidegger's work. It insists that questions of language and calculation in Heidegger are inherently political, and that a far broader range of his work is concerned with politics than is usually admitted.