PRIESTLEY, JOSEPH: English theologian and scientist; b. at Fieldhead in the parish of Birstall (28 m. s.w. of York), West Riding of Yorkshire, Mar. 13, 1733; d. at Northumberland, Pa., Feb. 6, 1804. He was the son of a cloth-weaver, and was brought up in the dissenting family of his aunt after 1742. Intended for the dissenting ministry, he mastered Latin and Greek at Batley grammar-school (1745), learned Hebrew under a Congregational clergyman, and studied also the rudiments of Chaldee, Syriac, and Arabic. His theological studies were interrupted by symptoms of tuberculosis, but were resumed in 1756 at Daventry Academy. Repelled by Calvinistic doctrine he embraced Arianism (q.v.) in distress that he could not feel a proper repentance for the sin of Adam. He became acquainted with David Hartley's Observations on Man, a book which exercised a decisive influence on his speculations, which also was ranked by him next to the Bible. He embraced Hartley's theory of association carrying with it the necessarian doctrine and in 1754 became a scientific determinist. In 1755 he became Presbyterian minister at Needham Market, Suffolk, but his success was impeded by an impediment in speech. He continued his theological studies and soon came to reject the doctrines of the atonement, the inspiration of the Bible, and all direct divine action on the human soul. In 1758 he became minister at Nantwich, Cheshire, and established a flourishing school, and in 1761 was appointed tutor in languages and belles-lettres at Warrington Academy. He was ordained in 1762; and removed to Mill Hill Chapel, Leeds, in 1767; became later a Socinian; in 1769 set on foot The Theological Repository, an organ of critical inquiry; and in 1773 entered the new religious movement under the Unitarian name (see UNITARIANS).
He then retired to Leeds, where he founded a circulating library and in 1773 removed to Calne, Wiltshire, as literary companion of the Earl of Sherbourne, which gave him leisure for study, during which his scientific experiments developed rapidly. Disquisitions Relating to Matter and Spirit (London, 1777), followed by Philosophical Necessity (1777), defined his position, which he called materialism. He had adopted the theory that matter consists only of points of force (1772); the doctrine of the penetrability of matter suggested itself before 1772; and after 1775 he had abandoned the distinction between soul and body for homogeneity. In 1780 he removed to Birmingham, where he was amply supplied by friends with funds for his living and for experiments, and the same year was made junior minister of the New Meeting. In his Greek Harmony of the Gospels (1777) he limited the ministry of Christ to a period of little more than a year; and his rejection of the doctrine of the virgin birth and of the impeccability and intellectual infallibility of Christ, and the opinion that he was born at Nazareth, were expressed in The History of Early Opinions concerning Jesus Christ (Birmingham, 1786). The best-known of his theological writings was History of the Corruptions of Christianity (1782). From 1786 Priestley issued an annual defense of Unitarianism and in 1791 concurred in the formation of the Unitarian Society. Supporting the principles of the French Revolution, he was one of the organizers of the Constitutional Society of Birmingham; and on the night of July 14, 1791, after the fall of the Bastile, a riotous mob burned his church and house with all his books, papers, and apparatus. He escaped by flight to London, and was partly indemnified after a legal contest covering nine years. He then settled down as morning preacher at Hackney, London, where he also continued his scientific pursuits and lectured on history and chemistry in Hackney College. He removed to the United States in 1794 and settled at Northumberland, Pa. There he held public services in his own house, and after 1799 in a wooden building, and succeeded in establishing a Unitarian society at Philadelphia. He worked out his doctrine of universal restitution, upheld Biblical institutions against those of oriental antiquity, annotated the whole Bible, and completed his General History of the Christian Church (Northumberland, 1802).
Priestley was a pioneer in the erection of chemistry into a science, in the investigation of gases, and the discovery of oxygen. He was a warm friend of Benjamin Franklin, whom he first met at London, after 1762. He was a member of the Royal Society from 1766 and was elected one of the eight associates of the French Academy of Sciences in 1772. He wrote a History of the Present State of Electricity (London, 1769). He was an original seeker after truth, was essentially devout, and a rapid, untiring, and thought-educing writer. He stands at the transition point marked by the dissolution of ultratheological views and the advent of agnosticism, occupying the central position of the first period of the Unitarian movement. Other works to be mentioned are: Analogy of the Divine Dispensations (Theological Repository, 1771) pronounced by James Martineau his finest piece of work; A Free Discussion of the Doctrines of Materialism (Birmingham, 1782); Institutes of Natural and Revealed Religion (1782); and Letters to a Philosophical Unbeliever (1787). The Theological and Miscellaneous Works (26 vols., London, 1817-32), and Memoirs and Correspondence (2 vols., 1831-32) were collected by J. T. Rutt, and name over 130 separate works.