Marx's critical theories about society, economics, and politics, collectively understood as Marxism, hold that human societies develop through class conflict. In the capitalist mode of production, this manifests itself in the conflict between the ruling classes (known as the bourgeoisie) that control the means of production and the working classes (known as the proletariat) that enable these means by selling their labour-power in return for wages. Employing a critical approach known as historical materialism, Marx predicted that capitalism produced internal tensions like previous socioeconomic systems and that those would lead to its self-destruction and replacement by a new system known as the socialist mode of production. For Marx, class antagonisms under capitalism, owing in part to its instability and crisis-prone nature, would eventuate the working class' development of class consciousness, leading to their conquest of political power and eventually the establishment of a classless, communist society constituted by a free association of producers. Marx actively pressed for its implementation, arguing that the working class should carry out organised proletarian revolutionary action to topple capitalism and bring about socio-economic emancipation.