Theorizing 2 + 2 = 5: strike it where you will, it rings like postmodernism

Nazi theory indeed specifically denies that such a thing as "the truth" exists. ... The implied objective of this line of thought is a nightmare world in which the Leader, or some ruling clique, controls not only the future but the past. If the Leader says of such and such an event, "It never happened" – well, it never happened. If he says that two and two are five – well, two and two are five. This prospect frightens me much more than bombs.

            -- George Orwell, "Looking Back on the Spanish War" (1943)