Abstract

The article deals with a seldom exposed but ubiquitous method in the 18th century philosophy, named conjectural history by Dugald Stewart. Its characteristic feature is a peculiar combination of historically verified facts and speculations, which in some authors are even openly fictitious. The hypotheses about prehistory (always set forth in the form of temporal historical narrative) are meant to aid a certain classic philosophical topos of the 18th century: the quest for origins. The article first surveys and compares common points as well as peculiarities of various “treatises on the origins” in the Scottish and French Enlightenment. In the second half it focuses on an implicit but clearly identifiable conjectural history in Diderot's Supplement to the Voyage of Bougainville, and on the application of conjectural history in the domain of the intellect and knowledge in the Encylopédie. It seems that the genealogy of knowledge in d'Alembert's Preliminary Discourse most manifestly confirms the initial designation of conjectural history: that it is in fact another name for philosophy. If this holds true, than it might prove useful to search for its first seeds in Descartes’ Discourse on method, a work which places itself on the cross-section of history and fable.