Otto Neurath's contribution to the philosophy of science and to the study of the meaning and methods of the social sciences may well appear to have been clearly defined by the end of the Seventies. For at least two decades at that time philosophical historiography had accorded Neurath the strictly positivistic position of founder and most fervent and intransigent representative of the Vienna Circle.¹ In the context of the rich and in many ways decadent culture of post-Habsburg Vienna in the Twenties and Thirties² he appeared as a social reformer and proponent of "empirical enlightenment", an exuberant figure bursting with vitality, political energy and scientific optimism.