HARTLEY, DAVID. - Philosopher, born at Armley (Yorkshire) on 30 Aug. 1705, died at Bath on 28 Aug. 1757.
A notable representative of the materialist current of the English Enlightenment, H. founded a psychophysical associationism which, in the second half of the eighteenth century, would develop with Priestley into a rigorous monistic materialism. LOCKE, JOHN (v.), H. sought to reduce the duality of the sources of knowledge to the unity of sensation, eliminating reflection and justifying the relations established by consciousness among the various sensory data through recourse to the law of association. Thus the way was opened, through a physical-mechanical explanation of sensation, to a materialist interpretation of psychic facts. H.’s principal work: Observations on man, his duty, his frame, and his expectations (2 vols., London 1749).