The foremost Cambridge Platonist, whose major works were The True Intellectual System of the Universe (1678), and A Treatise Concerning Eternal and Immutable Morality (published posthumously, 1731). The former, although massive, is only the first third of a projected larger work. Cudworth was educated at Emmanuel College, Cambridge. In 1645, as a supporter of the Puritans, he was made Master of Clare College, Cambridge, which he left after a crotchety reign in 1650, only to return to Cambridge as Master of Christ’s College in 1654. The major aim of Cudworth’s metaphysical work was to refute both materialism and hylozoism. He held that the mind cannot be the merely passive recipient of atomic impacts, and its independent reality is certified by its agency in the world. Cudworth developed the importance of agency in nature with an Aristotelian doctrine of ‘plastic natures’ or inner directive principles, which guide the formation of living things, and themselves have purposes, and operate even upon the soul, but are not conscious. This doctrine attracted a good deal of discussion, by Bayle (who found it atheistic in tendency), by Leibniz, and in the Encyclopédie.

Cudworth believed that ethics is given in eternal and immutable truths, apprehended by reason. However, in his moral psychology the emphasis is not upon the kind of conformity with reason later associated with Kant, but upon the question of whether we act out of love or out of self-interest.

Cudworth’s daughter was Damaris, Lady Masham.