Why be interested in anarchism today? Why be interested in this most heretical of political traditions, whose shadowy existence on the margins of revolutionary politics has lead many to dismiss it as a form of ideological mental illness? The central claim of anarchism – that life can be lived without a state, without centralised authority – has been an anathema not only to more mainstream understandings of politics, which bear the legacy of the sovereign tradition, but also to other radical and revolutionary forms of politics, which see the state as a useful tool for transforming society.

Furthermore, anarchism has often lacked the ideological and political coherence of other political traditions. While there is a certain body of thought that is unified around principles of anti-authoritarianism and egalitarianism, anarchism has always been heterodox and diffuse; while it has had its key exponents, anarchism is not constituted around a particular name, unlike Marxism. Indeed, despite the startling originality of some classical anarchist thinkers – and it is my intention in this book to bring this theoretical innovation to light – anarchists have usually been more concerned with revolutionary practice than with theory. Moreover, while anarchism has historically had a certain influence on workers' movements, as well as on other radical struggles, it has not been as politically hegemonic as Marxism. Anarchism has flared up in brilliant flashes of insurrection – revolts and autonomous projects throughout the nineteenth and twentieth centuries – but these have just as quickly died down again, or have been savagely repressed.