The Reading Room

Joseph Priestley: “Enlightenment Man”

If anyone does, Joseph Priestley (1733-1804) warrants the description “Renaissance man.”  But, to avoid confusion, since Priestley lived a couple of centuries after the Renaissance, let me argue here that this “Enlightenment man,” as much or more than any “Renaissance man,” took all knowledge as his purview. And then he added a list of new disciplines including (for example) psychology, education, demography, sociology, economics, and geology.
Priestley discovered oxygen and other gases, carbonation (he coined “soda water”), and electrical machines and lenes. But he took for his domain philosophy, education, religion, and politics. Characteristically of the age (essentially the “long 18th century), Priestley ardently and actively carried his ideas into the world, turning out political works and pamphlets and participating in the political clubs and associations that flourished in the Enlightenment. In time, his passion and uncompromising attitude attracted persecution from the clergy, aristocrats, the British government, and ultimately mobs whose violence finally culminated in the burning down of his house and church, forcing him to flee to America.
Priestley was born in Yorkshire, not surprisingly into a family of Protestant (Calvinist) Dissenters. His early education was in languages, then he went to a Dissenting Academy (he was legally barred from universities), which probably spared him to some extent religious doctrine and fed his interest in science, philosophy, and theology. But at the Academy, too, he experienced a storm of doubts about the religious doctrines he had been taught and began to form the ideas that he spent the rest of his life refining and espousing. As required, he became a minister and teacher, between 1755 and 1761 ministering in Suffolk and Cheshire.
In 1761, he transitioned to tutor in languages and literature at the Dissenting Warrington Academy, Lancashire. Ordained a Dissenting minister the next year,  he married Mary Wilkinson, daughter of ironmaster Isaac Wilkinson. She is described as “affectionate, generous, and supportive,” meaning that she made it possible for Joseph to focus on his work. Together they had a daughter and three sons.
His passion for science gathered unstoppable momentum, in 1765, he met Benjamin Franklin, who would become a lifelong correspondent and supporter, who urged him to publish what became The History and Present State of Electricity, with Original Experiments (1767). In it, Priestley undertook to demonstrate from the history of science that progress in science arose more from the steady accumulation of facts by many investigators than what could learned by the great work of a few men of genius. It was an argument for “facts” over hypotheses and theories, a point hammered home by Isaac Newton. Priestley added that prejudice and dogma only got in the way of individual inquiry and private judgment.
This thinking now shaped Priestley’s electrical experiments that foreshadowed the later development of the inverse square law of electrical attraction, identified charcoal as a conductor, and began to show relationships between  electricity and chemical change. It was enough, in 1766, to win his election to the Royal Society of London. That honor only inspired Priestley to seek yet wider fields of investigation.
The next year, he returned to the ministry at Mill Hill Chapel, in Leeds (not far from his childhood home), and his scientific career took off in earnest, achieving incredible momentum. He launched experiments in chemistry, which, beginning in 1772,  produced the first of six volumes he would publish between then and 1790: Experiments and Observations on Different Kinds of Air, and more than a dozen articles in the Royal Society’s Philosophical Transactions. The subject was gases, or “airs,” as they were known. British chemists had identified three: air, carbon dioxide, and hydrogen). First, Priestley worked out how the chemistry of those gases could be integrated into phlogiston theory (it was believed that combustible substances when burned released phlogiston, a “principle of inflammability”). 
In all, Priestley isolated and named 10 new gases (most then had different names): nitric oxide, nitrogen dioxide, nitrous oxide (“laughing gas”), hydrogen chloride, ammonia, sulfur dioxide, silicon tetrafluoride, nitrogen (“phlogisticated air”), oxygen (“dephlogisticated air”), [1] and a gas later identified as carbon monoxide. (As others were working simultaneously in the field, he is usually credited with “the independent discovery” of oxygen, his particular method the thermal decomposition of mercuric oxide to release the oxygen).
The key to his astonishing productivity was Priestley’s knack for designing ingenious apparatuses and his skill in using them. The Royal Society in 1772 awarded him their prestigious Copley Medal. He was 39. Priestley continued his science lifelong, but his interests were limitless. He ultimately published more than 150 works—his history of electricity, a seminal work in grammar, a history of the church—but mostly controversial works on religion, politics, and education.
Dissent, Dissent: Enlightenment Radicalism
For example, he defended Unitarianism (which many equated with deism, one step away from atheism). That meant viewing Jesus as a human prophet and rejecting the Trinity, original sin, and atonement. At a time of continuing strict orthodoxy, the establishment was alarmed at the attacks by leading philosophers of the age (although especially in France). Priestley argued for religious toleration, the inherent goodness of man, and salvation by moral conduct and faith (that is, salvation that was within the individual’s ability to attain). But the premises that led him to those positions (and underlay his passion for science) were precisely those views that persuaded many that the Enlightenment must be rejected as the enemy of human freedom, faith, and the view of man as spiritual. Priestley insisted upon strict materialism (no Cartesian dualism of mind and body) and determinism (by natural laws and by Providence—his Unitarianism).
He was equally “radical” in politics, a proponent of liberalism against monarchy, aristocracy, and, of course, the established church (he advocated separation of church and state). More specifically, he advocated republican government, democracy, consent of the governed, and the rights of man (particularly speech and press). That led naturally to his embracing both the American Revolution (1765-1783) and the French Revolution (1789-1799).
It seems, from this, that perhaps Priestley can be checked off as another young man of the 18th century who went whole hog for the ideals of the Enlightenment: A rationalist asserting human reason as the ultimate source of knowledge and truth, an empiricist wedding observation and experimentation, a naturalist confining explanation to natural causes and laws, a humanist embracing ideals of human freedom and earthly happiness, a reformer urging change in society, politics, and religion, and an optimist believing in the perfectibility of man and an ever-better world.
He did not originate these ideas, of course; John Locke, for example, had done his work and passed (1704) three decades before Priestley was born. But what Priestley achieved and the force he brought to explanation, argumentation, and advocacy of ideas moved important minds: in science, for example, Antoine Lavoisier, Henry Cavendish, and Benjamin Franklin; in philosophy, Jeremy Bentham, John Stuart Mill, and Herbert Spencer.
Intent upon work in science and philosophy, Priestley did not let slip the career as a minister he pursued in school. He started and supported new Unitarian congregations and religious societies, wrote many theological works and sermons, and conducted running arguments with the likes of David Hume, Edmund Burke, and Richard Price. He saw his religious works and ideas carried forward in the new American Republic by Thomas Jefferson, William Ellery Channing (the foremost preacher of Unitarianism in early 19th century America), and the Transcendentalists like Ralph Waldo Emerson.
He not only supported the American and French Revolutions; he actively called for a similar revolution at home, in Britain. Again, his works arrested the attention of leading intellectuals of his day such as Thomas Paine, James Madison, and the Chartists. [2] He wanted English history and civil law taught from the perspective of participation in decisions that would direct the nation—and wanted it taught to students of a social class that now should win a role in government.
Education for An “Active Life”
Priestley wanted to see an educational system suited for the future of students who would lead an “active life” in business, the professions, and citizenship. That is, he challenged root and branch the orthodoxy of scholasticism—the Christianized Aristotelianism of the Catholic Church then universal in European education. It was not enough (and time wasted) to teach Latin and Greek, rhetoric, logic, school divinity, and civil law. He wanted to move to the fore mathematics, history, abstract science, the arts, but also writing and even “merchant accounts.” [3] To do so, he wrote works on education (such as his “Essay on A Course of Liberal Education for Civil and Active Life”) as well as textbooks and taught at schools and academies. (Unfortunately, almost all teachers were clergy, whom he did not expect would change.) Among his famous students were William Godwin and Robert Owen. [4]
Typically, Priestley’s focus was on the texture of practical life. What if existing teachers and tutors simply could not answer questions in the new subjects? Perhaps they had been pretentious of knowledge. Too much encouragement of practical politics might not suit most students. Still, “a true friend of liberty will be cautious how he discourages fondness for that kind of knowledge which has ever been the favorite subject of writing and conversation in all free states.” And gentlemen who intend to serve their country “in the respectable character of merchants [should have] heard the great maxims of commerce discussed in a scientifical and connected manner as they deserve…”
Revolution and Revilement
Priestley's work must have seemed, at the time, to come down to overturning aristocracy, the “gentry,” who dominated society, government, the church, and education. In fact, it must have seemed what it was: advocacy of revolution. The aristocracy knew it was a special target and replied with contempt, ridicule—and violence. He was set up by caricatures and lampoons, portrayed as a madman, fanatic, and rebel. This aroused and incited those he viewed as the potential beneficiaries of his tireless efforts at education and reform. He was attacked by mobs that were instigated and funded by his upper-class enemies. He was threatened and assaulted by those aroused to hatred and prejudice. [5]
Officially, government censorship, prosecution, and exile loomed. His works, like those of  the French philosophes, were banned, burned, and confiscated by authorities,  and Priestley was accused of sedition, treason, and blasphemy. Both as dissenter and as radical he was denied civil rights and opportunities—voting, holding office, teaching at a university. The church responded with condemnation, excommunication, and ostracism. His work was denounced, refuted, and ridiculed by the clergy. “Heretic,” “infidel,” “apostate”: the names flew, and he was excluded by many religions and many institutions.
Among Priestley’s intangible and seemingly unanswerable foes was public ignorance—misunderstanding, and fear. His works were ignored, and misrepresented, and he was seen as a dangerous, radical, and subversive figure. There was scarcely a social or political problem--wars, famines, and revolutions--for which he could not be scapegoated.
The climax came on July 14, 1791, in Birmingham, when a mob incited to rage at supporters of the French Revolution [6] exploded into a frenzy lasting four days, now called “the Priestley Riots.” They burned down his home and church but also the property of many other religious dissenters. The family sought refuge in the congregation of Richard Price, in London, and for a while Priestley taught at New College, Oxford, enduring three years of hostility and harassment from government and the public. As conservatives recoiled with fury from the French Revolution’s terror, Priestley emigrated with his family to America in search of more freedom and tolerance. 
He found it. Although his ship, the Samson, docked in New York City (1794), he moved on to Philadelphia, where scientists and politicians, including notably, Thomas Jefferson (whom he met in 1797), made him and his wife, Mary, feel welcome. (His sons had immigrated to America earlier.) Priestley was feted for a time, by those who sought his political influence, but he was uncharacteristically careful. He wrote to John Adams (yet another correspondent) explaining that he "made it a rule to take no part whatever in the politics of a country in which I am a stranger, and in which I only wish to live undisturbed." Priestley never became a citizen of the United States. 
His problem, now, was money (although he turned down an opportunity to teach chemistry at the University of Pennsylvania.)  Like many in a comparable situation, he migrated to the Pennsylvania backcountry to Northumberland, where he and Mary could afford to build a new home and laboratory. It was she who designed it, in Georgian style with Federal accents (now operated as a museum). She declared herself delighted with the new setting and landscape. Joseph continued his work in science and produced books and pamphlets on chemistry, theology, history, and education. He advised Jefferson on the structure of the University of Virginia. 
Typically, he took the initiative, joining in the establishment of the first Unitarian church in America (but also stimulating the creation of a dozen new congregations around the country). When he preached, people flocked to hear him. There, on the American frontier, far from the Enlightenment hotbed of Britain and the Continent, but dwelling still in its philosophical universe, Priestley died on February 6, 1804, at age 70, and lies in the Riverview Cemetery in Northumberland.
Notes[1] With this term, Priestley committed himself to a theory, soon displaced, that postulated existence of a fire-like element called phlogiston. Priestley, who tended to be hard-headed, was determined to defend phlogiston theory, leading to rejection of what would be called “the chemical revolution,” and so isolated among scientists. He was used to it.

[2] After persistent measures by government and business to suppress the demands of workers and break up labor organizations, the English Chartists emerged in 1836 to push for political reform, especially electoral reform, which they had become convinced was more promising the labor violence (as of the Luddites). The changes included universal male suffrage, secret ballot, and annual Parliaments. They advanced these in 1838 in the People’s Charter of 1838. Ten years later, the movement had disappeared.

[3] He advocated the laissez-faire economics of the Scottish philosopher Adam Smith, urging limitation of the role of role of government and evaluation of government’s effectiveness solely in terms of the welfare of the individual. English economist and founder of utilitarianism, Jeremy Bentham, acknowledged Priestley’s influence and inspiration of utilitarianism’s famous descriptor “the greatest happiness of the greatest number.”

[4] Godwin, a journalist, political philosopher, and novelist was among the earliest exponents of utilitarianism and viewed as the first modern proponent of anarchism. He was married to feminist Mary Wollstonecraft. Owen was a Welch textile manufacturer, reformer, and founder of utopian socialism and the co-operative movement.  

[5] The question arises: If he was so widely damned, reviled, and feared, how did Priestley publish all those works? He was a relentless communicator, who through his prolific writing and “discoursing” kept in touch with potential supporters and patrons who stepped in financially and intellectually. They included Lord Shelburne, Thomas Jefferson, Benjamin Franklin, and Joseph Johnson (the legendary Enlightenment publisher who seemed to have taken on half the British Enlightenment as clients). As a joiner, too, he had access to printing presses and publishers such as the Warrington Academy, the Lunar Society, and the Society for Constitutional Information. Earl Shelburne was an Anglo-Irish Whig who became prime minister, 1782-83, and engaged with Enlightenment ideas and figures, including Benjamin Franklin, David Hume, Adam Smith, Dugald Stewart, and many French intellectuals and economists.[6]  It should be explained, though not in extenuation of mob violence, that Priestley continued his staunch support of the French Revolution even as it slipped into violence. Oddly, it seems, for a scientist, advocate of reason, and Unitarian, he interpreted the Revolution with all its horrors as a fulfillment of biblical prophecies and a precursor to the Kingdom of God. Thus, he clung to his views in the face of persecution and hostility from the British authorities and public. He was, it is worth repeating, a very hard-headed individual.