Dialectic, in philosophy, method of investigating the nature of truth by critical analysis of concepts and hypotheses. One of the earliest examples of the dialectical method was the Dialogues of Greek philosopher Plato, in which the author sought to study truth through discussion in the form of questions and answers. Another noted Greek philosopher, Aristotle, thought of dialectic as the search for the philosophic basis of science, and he frequently used the term as a synonym for the science of logic.

The German philosopher Georg Wilhelm Friedrich Hegel applied the term dialectic to his philosophic system. Hegel believed that the evolution of ideas occurs through a dialectical process—that is, a concept gives rise to its opposite, and as a result of this conflict, a third view, the synthesis, arises. The synthesis is at a higher level of truth than the first two views. Hegel's work is based on the idealistic concept of a universal mind that, through evolution, seeks to arrive at the highest level of self-awareness and freedom.

German political philosopher Karl Marx applied the concept of dialectic to social and economic processes. Marx's so-called dialectical materialism, frequently considered to be a revision of the Hegelian system, asserts that ideas can arise only as a result of a material condition.