How did Proudhon's disagreements with Karl Marx divide socialist thinkers?

The disagreements between Pierre-Joseph Proudhon and Karl Marx created a fundamental, enduring rift between libertarian and authoritarian socialists, as well as between anarchists and Marxists.1

This division was driven by several key ideological conflicts:

• Political Strategy: Proudhon advocated for mutualism and economic action by workers to liberate themselves, rejecting democratic and parliamentary politics. In contrast, Marx and his followers championed political action and the seizure of the state to establish a dictatorship of the proletariat.213
• The Role of the State: Proudhon viewed the state as an inherently coercive institution that should be replaced by a federal system of autonomous associations. Marx’s focus on state power as a necessary tool for transition was fundamentally at odds with this anarchist vision.241
• The Nature of Socialism: Marx famously attacked Proudhon’s ideas in his work The Poverty of Philosophy, deepening the hostility between the two factions.1

This conflict eventually fractured the First International, as Marx’s centralist approach clashed with the followers of Proudhon and later Mikhail Bakunin, who continued to oppose Marxist authoritarianism.213