W. K. Clifford

William Kingdon Clifford (1845–1879) was a British mathematician and philosopher, Fellow of Trinity College, Cambridge, and from 1871 Professor of Mathematics and Mechanics at University College London. Though best known in mathematics for Clifford algebras and contributions to non-Euclidean geometry, his lasting influence on the philosophy of religion derives from a single essay, 'The Ethics of Belief' (1877), in which he advanced the now-famous principle: 'It is wrong always, everywhere, and for anyone, to believe anything upon insufficient evidence.' Illustrated by the parable of the shipowner who sends an unseaworthy vessel to sea on the strength of stifled doubts, the essay framed belief-formation as a moral act with social consequences, since credulity corrupts the shared epistemic standards on which communities depend. Clifford's evidentialism became the canonical foil for William James's 'The Will to Believe' (1896), and the Clifford–James debate remains a touchstone in religious epistemology, revisited by Alvin Plantinga and Nicholas Wolterstorff in their critiques of classical foundationalism and by Peter van Inwagen, Susan Haack, and others in contemporary work. Influenced by Darwin, Spencer, and Mill, Clifford promoted a thoroughgoing scientific naturalism and was sharply critical of religious dogma. He died of tuberculosis at thirty-three, leaving philosophical essays collected posthumously by Leslie Stephen and Frederick Pollock.