Duplex intellectus et sermo duplex: Method and the Separation of Disciplines in Johannes De Raey

What induced one of the first partisans of Descartes in the United Provinces to express serious concerns about the development of Dutch Cartesianism in his old age? Examining Johannes de Raey’s intellectual development, we find a growing interest in the separation of disciplines. In his youth, he endorsed this separation in order to protect philosophy from the domination of theology, but from the late 1660s, De Raey rather sought to prevent the use of a criterion of evidence in the higher faculties (law, medicine, and theology). De Raey claimed this use to be very dangerous, as the writings of Lodewiijk Meyer and Baruch Spinoza attest. Whereas the link between metaphysics and physics is matter of primary importance in Descartes, according to De Raey this relationship can only be fully understood considering a broader and more important issue - separating philosophy and theology.