«[P]er experientiam scilicet, vel deductionem». Descartes’ Battle for Scientia in the Early 1630s

After his second arrival in the Dutch Republics, René Descartes’ (1596-1650) challenging project to explain global physics was initially discussed in his correspondence, in which he disclosed his demand for every singularity to be encompassed within a chain of thoughts. This effort intriguingly complements Descartes’ Regulæ ad directionem ingenii, where mental cognition shapes scientia. Yet, while discussing several precise scientific topics, Descartes’ early 1630s miscellaneous epistolary with Marin Mersenne (1588-1648) and Isaac Beeckman (1588-1637) gives voice to a key battle for the definition of scientia in opposition to the scientific approaches of his correspondents, illustrating Descartes’ original combination of experience and reason. The epistemology of the Regulae emerges in this bellicose correspondence, where every ingredient within knowledge was submitted to his scientia and Descartes’ methodological procedures were applied in scientific fields