English theologian and rationalist. Clarke studied at Cambridge, and became rector of St James, Westminster, where he was an influential minister. He is remembered as a natural theologian, whose cosmological proof of the existence of God was delivered in the Boyle lectures of 1704 (‘A Demonstration of the Being and Attributes of God’). His derivation of the basis of morality from right reason alone was presented the following year (‘A Discourse concerning the Unchangeable Obligations of Natural Religion’). Both provided convenient targets for the naturalistic philosophers of the Enlightenment. He is mainly remembered for his defence of Newton (a friend from Cambridge days) against Leibniz, both on the question of the existence of absolute space and on the question of the propriety of appealing to a force of gravity. The exchange has been collected as The Leibniz-Clarke Correspondence (1956). Clarke had the last word (publishing his fifth reply after Leibniz's death) but Leibniz won the argument. In his Lettres philosophiques (1734), Voltaire describes Clarke as a ‘veritable reasoning machine’.