Dialectic: A central but ambiguous category in philosophy from  Plato through Hegel and Marx to Mao t’se Tung, it is most coherently understood as a heuristic concept modeled on a dialogue in which opposing arguments clash to yield through their conflict a higher unity or synthesis.

Source: What is Good? What is Bad? The Value of All Values across Time, Place and Theories’ by John McMurtry, Philosophy and World Problems, Volume I-III, UNESCO in partnership with Encyclopedia of Life Support Systems: Oxford, 2004-11.