Why did Marx regard class conflict as a force driving historical change?

For Karl Marx, class conflict is the driving force of history because it is the inevitable result of contradictions within a society's mode of production. Marx’s theory of historical materialism posits that human history is fundamentally shaped by how a society organizes its economic activity to produce the necessities of life.

As technology and knowledge evolve, the "material forces of production" change, eventually coming into conflict with existing "social relations of production"—the established division of labor and class structures. These material contradictions cannot be resolved through reason; instead, they create opposing interests between classes, such as the bourgeoisie (who own the means of production) and the proletariat (the working class).12

Marx viewed these class struggles as the "motor of history." When a mode of production creates a new class that can no longer accept its place in the social order, it triggers revolutionary upheavals that replace the old system with a more advanced one. This continuous process of opposition and adaptation is what Marx believed drives the development of human civilization.12