A central feature of Scottish Enlightenment thought was the emergence of stadial or “conjectural” theories of history, in which the development of all human societies, from those in Europe, to the Seminole Indians in Florida and the Tongans of the South Pacific, could be understood and compared according to the same universal historical criteria. This paper argues that central to this tradition was an account of the relationship between “useful knowledge” and social development. This article argues that we can map the circulation of a discourse about useful knowledge, nature, and civilisation through a network of Scottish-trained physicians and naturalists that spread to the Atlantic and to the Pacific. In the Atlantic world, physicians and naturalists used the vocabulary and categories of stadial theory to classify indigenous societies: they made comparisons between the illnesses that they thought “naturally” afflicted savage cultures, as opposed to those of civilized Europeans. In the Pacific, the Edinburgh-trained surgeons and naturalists compared Tahitians, Maoris, and Australian Aborigines to black Africans and Europeans, and they commented on the presence or absence of useful knowledge as a marker of the degree of development of each civilisation.