This chapter will look at various aspects of the relationship between Saussurean linguistics and debates within twentieth-century philosophy of science. After all it was Saussure's chief aim to see linguistics placed on a properly 'scientific' footing, that is, to reconfigure the field in accordance with certain well-defined principles that would constitute an adequate, rigorously theorised account of language and signifying systems in general. The first task was to elaborate those various distinctions that would henceforth provide its working methodology, among them the cardinal oppositions between langue and parole, synchrony and diachrony, the paradigmatic and the syntagmatic, and the orders of signifier and signified. This would open the way to a structuralist account that left no room for naive (pre-scientific) ideas about the one-to-one 'correspondence' between words and ideas or words and objects. Rather it would show how the systematic character of language - its differential structures of sound and sense - can only be described by means of a theory which itself breaks free of such delusive 'commonsense' beliefs and acquires the full range of conceptual resources whereby to articulate its own grasp of those same signifying structures.