Pierre-Joseph Proudhon was a French socialist, politician, philosopher, economist 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 anarchism's most influential theorists. Proudhon is considered by many to be the "father of anarchism". Proudhon became a member of the French Parliament after the Revolution of 1848, whereafter he referred to himself as a federalist. Proudhon described the liberty he pursued as "the synthesis of communism and property". Some consider his mutualism to be part of individualist anarchism while others regard it to be part of social anarchism.
Proudhon, who was born in Besançon, was a printer who taught himself Latin in order to better print books in the language. 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, published in 1840. The book's publication attracted the attention of the French authorities. It also attracted the scrutiny of Karl Marx, who started a correspondence with its author.