Hartley, David (1705–1757)

3. Influence

Hartley’s particular neurophysiological theories proved erroneous, yet his work was of cardinal significance in the development of attempts to apply scientific concepts to the study of the individual as a social being and as a progressive creature. His was the first methodical elaboration of the explanatory principle (psychophysical parallelism) that came to play a role in the human sciences analogous to that played by the concept of gravity in the physical sciences. Though Hartley was personally devout, his unification of sensation, motion, association and volition within a mechanistic theory of consciousness and action created a framework of thinking that later supported more secular readings of the concepts of utility. His agenda was widely taken up in late Enlightenment and nineteenth-century doctrines as a means of accounting for cumulative ordered change through experience, changing responses being explained in terms of adaptation to pleasurable and painful consequences. Hartley put learning theory and moral judgment on a scientific basis.

Hartley had an influence on Samuel Taylor Coleridge, whose brief flirtation with his notions led to his first-born being baptised Hartley Coleridge. Joseph Priestley stressed Hartley’s determinism, but omitted his materialist neurology in his edition of the Observations on Man, retitled [Hartley’s] Theory of the Human Mind (1775). Priestley put his modified version of Hartley’s theory at the service of a Unitarian philosophy of nature. Erasmus Darwin used Hartley’s neurological mechanisms as the basis for his system of medical classification in Zoonomia (1794–6) and for his theory of evolution in the Temple of Nature (1803). In sociopolitical theory, the arguments advanced in William Godwin’s Political Justice (1793) for inevitable human progress towards perfection were based on inferences from Hartley. The psychological, social, and political theories of James and John Stuart Mill and other English utilitarians were also based on Hartleian psychology and generalizations from it. In the nineteenth century, Hartley’s fusion of corpuscular physics with empiricist epistemology and sensationalist psychology became reworked in more modern evolutionary terms to provide the foundations for theories in biology, neurophysiology, psychology, psychiatry, sociopolitical theory and to endorse a general faith in progress. Hartley’s psychophysiological theory of learning underpins modern, evolutionary human science.