This work was written by C. Marx in French as a response to a book by French politician and sociologist P.-J. Proudhon's "System of Economic Contradictions, or Philosophy of Poverty." In his "Poverty of Philosophy," the author, in the form of criticism of Proudhon, first outlined to the general public the initial provisions of his economic teaching, proposing what after twenty years turned into a harmonious theory developed in Capital. This edition includes two letters by K. Marx, also containing criticism of Proudhon's views.