  Eddington was the first to attack Milne’s views. In a series of lectures given at Harvard in late 1932 and published early in the new year as The Expanding Universe, Eddington denied the efficacy of both operationalism and hypothetico-deductivism, and not only defended explanatory realism, but strengthened his ontological position heroically: the theoretical entities of relativistic cosmology were not just plausible, they were so necessary to understanding the universe, that cosmological knowledge was essentially impossible without them (Eddington 1933, p. 19).