This chapter considers Locke’s criticisms of Descartes’s views about the mind. Although Locke grants that dualism might be true (i.e., that human beings might have an immaterial mind), he thinks the Cartesian version of that view is false. The chapter focuses on two topics within Locke’s discussion of Descartes’s views: whether we have an innate idea of God, and whether the mind is always thinking. On the first issue, Locke rejects the view of Descartes (and More, Cudworth, and others) that we have an innate idea of God, but also rejects Hobbes’s view that we have no idea of God. On the second issue, Locke opposes Descartes’s view that the mind is always thinking, as well as his related view that thinking is the principal attribute of the mind, and indeed his metaphysical scheme of substance, principal attribute, and mode.