Joseph Priestley (1733 - 1804), best known as the discoverer of oxygen, was a Unitarian minister, educator, theologian, historian, and political radical, as well as a proponent of the New Science.

Like many of natural philosophy's champions in eighteenth-century Britain, Priestley rejected the divinity of Christ and division of God into three persons, but he went one step further by denying the existence of an immaterial, immortal soul in addition to the Trinity. In his polemical treastise, Disquisitions on Matter and Spirit (1777) Priestley denies the immortality of the soul on both scientific and Biblical grounds. Heavily indebted to the thinking of the physician David Hartley, Priestley argued that the functions in the body that had been assigned to an immaterial soul (perception and thought) are linked to material structures in the brain and therefore will not outlive the cerebral tissue that produced them. From a Scriptural standpoint, Priestley believed that if the soul were immaterial and therefore immortal, the concept of the resurrection of the body would have no meaning since a person's essence would remain intact with or without his body. Hence, he concluded, though confirmation or rejection of spirit was impossible on the basis of observation, in all likelihood, man was an entirely material being. Despite the atheistic sound of this proposal, Priestley re-asserted his faith in Revelation and held that anyone who deviated from the orthodox Anglican line was branded an atheist. For this reason Priestley was able to rehabilitate Thomas Hobbes as "no atheist, but a sincere christian, and a conscientious good man" in Free Discussion of the Doctrine of Materialism (1778).

Such scandalous opinions did not help his reputation with the Anglican divines or the civil authorities (e.g. he lost his patron, the second Earl of Shelbourne), nor did Priestley's outspoken support for the French Revolution in its early phases. After an angry Birmingham mob (probably incited by the local clergy) burned down Priestley's home and laboratory in 1791, he settled in Pennsylvania, where he died.

-- Dale Bowling

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