OBJECTOR 1

Johan Caterus (1590–1655). A Calvinistically inclined Dutch priest who was chiefly concerned with the theological aspects of the Meditations, especially Descartes's proofs for the existence of God.

OBJECTOR 2

Marin Mersenne (1588–1648). A long-time friend and proponent of Descartes and opponent of Aristotle who wrote his own anti-skeptical treatise, the Véritez des sciences in 1625. Mersenne did not author the entire Second Set of Objections but collected them from his circle.

OBJECTOR 3

Thomas Hobbes (1588–1679). The English materialist and political philosopher, author of the Leviathan, for a time resident in France. Hobbes insisted that there could be no incorporeal substances and that thinking was a mechanical operation. He regarded theology as obfuscation by priests.

OBJECTOR 4

Antoine Arnauld (1612–94). A young Jansenist theologian, strongly influenced by St. Augustine. To all appearances, the most aggressive and focused of Descartes's critics, but later a defender of Descartes and considered to be a Cartesian.

OBJECTOR 5

Pierre Gassendi (1592–1655). The chief seventeenth-century proponent of the systems of Epicurus and Lucretius, which he endeavored to reconcile with Christianity. Gassendi believed that atomic mechanisms underlay natural phenomena but doubted that humans were able to reveal and understand them.

OBJECTOR 6

Friends of Marin Mersenne of unknown identity, some of them described as “philosophers and geometers.” They raise Scriptural and other theological objections to Descartes but also find his theory of the incorporeal soul insufficiently grounded.