Towards Descartes’ Scientific Method: a posteriori Evidence and the Rhetoric of Les Météores

I argue that Descartes uses his method as evidence in the Discours and Les Météores. I begin by establishing there is a single method in Descartes’ works, using his meteorology as a case study. First, I hold that the method of the Regulae is best explained by two examples: one scientific, his proof of the anaclastic curve (1626), and one metaphysical, his question of the essence and scope of human knowledge (1628). Based on this account, I suggest that the form of his early metaphysics (not its content) is similar to the method of doubt of the Meditationes. Second, I argue that Descartes’ explanation of the cause of parhelia (1629) likewise contains a formulation of this procedure. I provide a novel reading of Les Météores, where, following Descartes’ guidance in the Discours and Correspondance, I interpret his meteorology by reasoning from effects to causes, in this case, from Christoph Scheiner’s 1626 observation of parhelia to his meteorological foundation. This backwards orientation to Les Météores, I argue, reveals an instance of Descartes’ scientific method. I conclude with remarks on Descartes’ concept of evidentia, in which I explain how he incorporates a posteriori evidence and an apparent hypothetical foundation into his rationalist epistemology where he uses his method as evidence for his claims.