Malebranche accepted a substance dualism in which the soul has the property of “spirituality” or immateriality. In this chapter, Section 1 traces the evolution in his thought from his initial suggestion that consciousness directly reveals the spirituality of the soul to a later demonstration of spirituality that proceeds from the premise that the nature of body consists in extension to the conclusion that the substance that is the subject of sensible qualities is distinct from body. Section 2 then takes up Arnauld's critique of Malebranche's claim that such a demonstration does not rely on a clear idea of the soul. The upshot here is that this critique fails to confront Malebranche's central charge that Cartesians have only an indirect knowledge of the soul's spirituality. Finally, Section 3 indicates that though Malebranche's indirect demonstration differs significantly from Descartes's main argument for mind–body distinctness, certain remarks in Descartes render him vulnerable to Malebranche's claim that Cartesians cannot discern spirituality in the nature of the soul alone.
Keywords: Arnauld, Descartes, immateriality, Malebranche, mind–body distinction, soul, spirituality, substance dualism