Born at Montireau in the region of Beauce, Lamy was a soldier before joining the Maurists, a congregation of French Benedictines, in 1658. While in Paris he studied mathematics with the Cartesian Jacques Rohault (1618–72) and subsequently became one of the first of the Maurists to teach Cartesianism. His published works display the strong influence of Nicolas Malebranche (1638–1715). In particular, Lamy holds the two positions that are most often associated with Malebranche, namely, that there is a universal, uncreated Reason to which we have access via a vision in God, and that God is the sole efficient cause in the world. His works include Le nouvel athéisme renversé, ou Réfutation du sistème de Spinosa (1696), Lettres philosophiques sur divers sujets importans (1703), and Les premiers élémens des sciences (1706). But his magnum opus is his five-volume De la connoissance de soi-mesme (1694–98). While many of the positions he defends there are taken from Malebranche, an exception is his main argument for occasionalism, which is one not found in the other major French occasionalists. It is based on the need for God's causal power to account for what appears to be interaction between the mind and body, understood in Cartesian terms as an immaterial thinking thing and an unthinking extended thing, respectively, given the fact that they are radically distinct substances. This argument led to a dispute with Gottfried Leibniz (1646–1716), who felt that his own doctrine of preestablished harmony was a better way to explain such “interaction.” The second edition of De la connoissance de soi-mesme (1699, in six volumes) contains Lamy's response to Leibniz, in which he argues that preestablished harmony is not compatible with human freedom (see free will). Lamy also engaged in disputes on various philosophical and theological matters with Bossuet, Nicole, Arnauld, Fontenelle, Régis, and even Malebranche. He died April 11, 1711, at the Abbey of Saint-Denis.

See also Body; Cause; God; Leibniz, Gottfried Wilhelm; Malebranche, Nicolas; Mind; Reason; Rohault, Jacques