This chapter presents a reconstruction of aspects of Arthur Cecil Pigou's philosophical biography. Utilitarian traditions as they pertain to the study of political economy in Britain are noted and then placed in the context of changes that occurred in philosophy and science during the second half of the nineteenth century. It is argued that the philosophical influences dominant in Britain during the period of Alfred Marshall's formative intellectual development, which broadly corresponds with the early period of British idealism, are distinct in many ways from the influences that had become prominent by Pigou's undergraduate years at Cambridge (and in the period up to the First World War). It is argued that these divergent philosophical frameworks explain some of the differences in Marshall's and Pigou's respective philosophical visions of the representation of economic theory.