Modern standard big bang cosmology was preceded by a 15-year controversy with the rival steady-state theory of the universe. At a time when cosmologically relevant observations were scarce and cosmology was widely regarded as an immature science, or not a science at all, much of the debate took place by means of arguments that were essentially philosophical. Remarkably, professional philosophers, including some of the key figures of Anglo-American philosophy of science, took an active part in the debate; no less remarkably, the involved astronomers and physicists sometimes listened to them. This article reviews the controversy over the steady-state theory as seen from the perspective of contemporary philosophy of science and offers an appraisal of how and to what extent philosophers and scientists entered a dialogue.