Pierre-Joseph Proudhon, politician and philosopher, 1809-1865

Pierre-Joseph Proudhon was a French politician and the founder of mutualist philosophy. He was the first person to declare himself an anarchist using that term and is widely regarded as one of the ideology's most influential theorists. He became a member of the French Parliament after the Revolution of 1848, whereafter he referred to himself as a federalist. His best-known assertion is that "property is theft!", contained in his first major work, "What Is Property? Or, an Inquiry into the Principle of Right and Government" (1840). He considered social revolution to be achievable in a peaceful manner.