Doubt and certainty › Objections and Responses

The *Meditations* were published with sets of objections from leading philosophers and theologians, along with Descartes' replies. Descartes sent the work for criticism before publication and wanted to test whether the reasoning that convinced him would convince others. Three useful questions to keep in view concern the cogito, the proofs of God, and the mind-body distinction. A reader can ask how much the cogito establishes about the thinker. Does the certainty that thinking occurs already establish everything Descartes later says about the nature of the self? The Second Meditation itself leaves further questions about that nature to be investigated. Descartes rejects treating the cogito as a syllogism from a general premise ("All thinking things exist") to a particular conclusion ("I exist"). It is an immediate intuition: in the very act of thinking, I am aware of myself as thinking. The existence of the thinker is given in the thought itself. Against the proofs of God, objectors raised the concerns mentioned earlier: the idea of infinity might be formed by negating finitude; existence might not be a perfection that can be included in a concept. Descartes maintained that the idea of infinity is positive, not negative, and that existence is indeed a perfection. Those answers leave an objector free to challenge the premises. In her letter of 6 May 1643, Princess Elisabeth asks how the soul can determine the movement of bodily spirits if it is only a thinking substance. Her question belongs to later correspondence, not to the objections printed with the first edition of the *Meditations*. Descartes answers by distinguishing notions of thought, extension, and the union of mind and body. Elisabeth presses him to explain the interaction more clearly. The [Stanford Encyclopedia entry on Elisabeth](https://plato.stanford.edu/entries/elisabeth-bohemia/) discusses the exchange and its philosophical significance.