Pierre-Joseph Proudhon was a French socialist philosopher, economist, and politician. Often described as the founder of modern anarchism, Proudhon played a major role in the theoretical development of socialism in the early 19th century, though his views shifted when he later joined the government after the French Revolution of 1848. Proudhon’s What Is Property? influenced Marx, though he would later break with Proudhon and attack his theory of capitalism in The Poverty of Philosophy (a polemical critique of Proudhon’s Philosophy of Poverty). Marx and Engels were already skeptical of Proudhon by the time they wrote The Germany Ideology, but they nevertheless defend him against what they consider to be ignorant critiques by Stirner and Grün.