“The Plan of a Universal Science [Le project d'une Science universelle] which is capable of raising our Nature to its Highest Degree of Perfection, together with the Dioptrics, the Meteors and the Geometry, in which the Author, in order to give proof of his universal Science, explains the most abstruse Topics he could choose, and does so in such a way that even persons who have never studied can understand them” (AT I 339, CSMK 51). This long and cumbersome original title of Descartes’ Discourse on Method (1637) conveys the highly ambitious yet elusive nature of Descartes’ method. He sometimes seems to present it as an epistemological panacea, claiming that it can “solve all the problems that have never yet been solved” in geometry (AT I 340, CSMK 51) and that it even “extends to topics of all kinds” (AT I 349, CSMK 53). Employing this wonderful method, Descartes claims, we could “make ourselves, as it were, the lords and masters of nature” (AT VI 62, CSM I 142–43). Indeed, in one of his most conspicuous expressions of his appreciation for his own method, Descartes boasts that it is far superior to that of his critic, Hobbes, even though the latter never claimed to have any method (AT VII 174, CSM II 123).

The two main texts in which Descartes discusses his method are the posthumously published Rules for the Direction of the Mind and the Discourse. Unfortunately, neither of the two works provides a complete presentation of the method. The Rules is an unfinished work; it was intended to contain thirty-six rules, but the extant versions of the work include only twenty-one (and the last three of these do not have the detailed elaboration that accompanied the others). Descartes worked on the Rules throughout the 1620s but had deserted it by 1628 (Garber 1992, 31).