Dialectic
In Ted Honderich (ed.), The Oxford Companion to Philosophy, Oxford, 1995, p. 198

In ancient Greece, dialectic was a form of reasoning that proceeded by question and answer, used by Plato. In later antiquity and the Middle Ages, the term was often used to mean simply logic, but Kant applied it to arguments showing that principles of science have contradictory aspects. Hegel thought that all logic and world history itself followed a dialectical path, in which internal contradictions were transcended, but gave rise to new contradictions that themselves required resolution. Marx and Engels gave Hegel's idea of dialectic a material basis; hence dialectical materialism.

Bibliography

Peter Singer, Hegel (Oxford, 1983), ch. 5.