Marx's criticism of Hegel asserts that Hegel's dialectics go astray by dealing with ideas, with the human mind. Hegel's dialectic, Marx says, inappropriately concerns "the process of the human brain"; it focuses on ideas. Hegel's thought is in fact sometimes called dialectical idealism, and Hegel himself is counted among a number of other philosophers known as the German idealists. Marx, on the contrary, believed that dialectics should deal not with the mental world of ideas but with "the material world", the world of production and other economic activity. For Marx, a contradiction can be solved by a desperate struggle to change the social world. This was a very important transformation because it allowed him to move dialectics out of the contextual subject of philosophy and into the study of social relations based on the material world.

Engels made constant use of the metaphysical insight that the higher level of existence emerges from and has its roots in the lower; that the higher level constitutes a new order of being with its irreducible laws; and that this process of evolutionary advance is governed by laws of development which reflect basic properties of 'matter in motion as a whole'.