Science and the Abolition of Slavery

Founding-era scientists also joined the fight against slavery.

Most people are aware that slavery in America and elsewhere, many years ago, was sometimes justified by false but seemingly “scientific-sounding” arguments that came to be called “eugenics.”  But what many people don’t know is that, at the same time, there was a robust counter-movement in the scientific community to dispel such false arguments and encourage the abolition of slavery.  The story of the anti-slavery movement within the scientific community in the eighteenth century is told by Eric Herschthal in his book The Science of Abolition: How Slaveholders Became Enemies of Progress.

As Herschthal writes:

[F]ew have realized that antislavery advocates, as much as their proslavery adversaries, relied on scientific discourse to defend their views. Taken together, this antislavery scientific discourse amounts to what I call the science of abolition— a wide range of scientific arguments that helped legitimate the antislavery movement and that ultimately cast slaveholders as unscientific and premodern: the enemies of progress … Though perhaps only a minority of men of science joined abolitionist societies, the ones who did were often prominent— and highly visible— members … [B]etween 1787 and 1818, three of the four presidents of the Pennsylvania Abolition Society, the early republic’s leading antislavery society, were men of science ...

These scientist abolitionists tended to reside in the Northern United States, where “every northern state had enacted some form of emancipation law by 1804,” and they included Joseph Priestley, Benjamin Franklin, and Erasmus Darwin: “Priestley discovered the element we now call oxygen. Franklin discovered the nature of electrical currents. Darwin devised new theories of human evolution that would influence his grandson Charles [Darwin].”  So involved were scientists in the anti-slavery cause that ex-slave and famed orator Frederick Douglass “routinely ran scientific articles against slavery in the North Star and his eponymous paper.”

The story of America’s scientist abolitionists further counters the false history perpetuated by some of today’s false “woke” historical narratives.  As I wrote in a previous essay:

In the [Nikole] Hannah-Jones introductory essay to the 1619 Project, she wrote “one of the primary reasons the colonists decided to declare their independence from Britain was because they wanted to protect the institution of slavery.”  That’s false. Gordon S. Wood, one of the nation’s most preeminent historians of the American Revolution, wrote that “I don’t know of any colonist who said that they wanted independence in order to preserve their slaves ... No colonist expressed alarm that the mother country [England] was out to abolish slavery in 1776.”

Not only is Hannah-Jones’ statement false, but nearly the exact opposite is true.  As Herschthal writes:

[T]he American Revolution transformed what had been disparate and uncoordinated attacks on slavery into an organized political movement … Patriot leaders responded that they cared little for slavery and would rather see it disappear if only Parliament would let them. They were not being entirely disingenuous, either. In 1772 the Virginia colonial legislature passed a bill to curtail the slave trade, only to see Parliament reject it; two years later, the Continental Congress adopted a resolution in favor of banning slave importations.

As I also wrote in a previous essay:

[S]lavery was a worldwide phenomenon for thousands of years, and it still exists in parts of the world.  Human slavery is a supreme evil.  It was also everywhere.  This map shows the volume of slaves sold by African slave traders worldwide, with the width of the line indicating the relative volume of the sales.  Much larger numbers of black slaves were sold by African warlords to slaveowners in the Middle East, and South America.  Now, that everyone was doing it doesn’t excuse in the least the supreme horrors of slavery -- but it does put the lie to the false narrative that slavery uniquely defines America’s identity.  And slavery wasn’t a strictly white versus black phenomenon.  The source of the slave trade -- without which it wouldn’t have existed as it did -- was overwhelmingly black African warlords, who enslaved other Africans for sale and profit.  As Peter Lovejoy writes in Transformations in Slavery: A History of Slavery in Africa: “Slavery has been an important phenomenon throughout history. It has been found in many places, from classical antiquity to very recent times. Africa has been intimately connected with this history, both as a major source of slaves for ancient civilizations, the Islamic world, India, and the Americas, and as one of the principal areas where slavery was common. Indeed, in Africa slavery lasted well into the twentieth century – notably longer than in the Americas.”

Even brilliant scientists like Benjamin Franklin, who went on to vociferously oppose slavery, had been born into that milieu, in which a sort of moral relativism overlooking the horror of African slavery came to overtake independent moral judgment. That resulted in apparent contradictions within Franklin, but also in his ultimate and very public denunciation of slavery:

Franklin’s commitment to antislavery was suspect. For one thing, Franklin owned enslaved people, several of them. In 1735 Franklin, then twenty- nine, bought his first enslaved servant, Joseph. Over the course of his life, he would acquire at least seven more, most of whom lived in his Philadelphia home, and two of whom, Peter and King, traveled with him to London in 1757. He freed none of them during his lifetime. Some died under his family’s control; King escaped to freedom three years after arriving in London; and only one, Bob, was manumitted “after my decease,” as Franklin wrote in his 1788 will. A good portion of Franklin’s wealth indirectly derived from the sale of enslaved people: at least 20 percent of the advertisements published in Franklin’s newspaper, the Pennsylvania Gazette, between 1729 and 1748 concerned enslaved or indentured laborers. Franklin’s investment in slavery did not necessarily make him a hypocrite. Slavery touched nearly every facet of eighteenth-century colonial life, and many early abolitionists had once owned slaves or profited from slavery. But Franklin’s late-in-life endorsement of the PAS [Pennsylvania Abolitionist Society] was hardly a tale of a compromised man who finally came to his senses. Near the end of his life, Franklin became the public face of the PAS— its leaders elected him president from 1787 to 1790 …

Franklin’s arguments against slavery focused not its inherent evil, but, perhaps for rhetorical reasons, on its negative effects on white Americans.  As Herschthal writes:

Franklin … made no mention of the harm, physical and otherwise, that slavery did to the enslaved, instead focusing only on the harm it did to white colonists. “Whites who have Slaves” become “enfeebled” and lazy, he wrote, eventually becoming “proud, [and] disgusted with Labour.”

Indeed, as I explored in previous essays, Franklin was on to something with that approach, as the effects of slavery did indeed include the devastation of the Southern economy, where the reliance on human slavery denied the South the vast technological progress that occurred in the North, where innovations in industrial machinery, not human slavery, was what improved other people’s lives.  (Joseph Priestley, who discovered oxygen, among many other accomplishments, pointed to other ways in which slavery hurt the economy, as well as progress generally.  As Herschthal writes, “In a 1788 book of lectures titled Lectures on History and General Policy, Priestley explained how slavery slowed the pace of scientific discovery. New technological inventions, he argued, came about only when human beings had a “considerable degree of security and independence,” and slavery represented the exact opposite of security and independence. In addition, he argued that new inventions thrived on consumer demand, but because slaves could not spend money, slave societies were infertile grounds for technological innovation.”)

Regarding Franklin’s views on race, Herschthal writes that

In December 1773 … the Marquis de Condorcet, a renowned man of science and abolitionist in France, asked Franklin about the condition of free Blacks in Philadelphia in relation to a work of natural history he was researching. “Generally improvident and poor,” Franklin responded, though he added that they were “not deficient in natural Understanding, but they have not the Advantage of Education.”

In this way, Franklin’s views were similar to those of Thomas Jefferson, which he arrived at after having become familiar with the work of Benjamin Banneker, a free black mathematician and scientist who lived during America’s founding.  Banneker published an almanac including the calculated location of the stars each day, and sent a copy along with a letter to Jefferson, who had previously expressed the notion that black people were biologically inferior.  Although Jefferson continued to have ambivalent thoughts, he was deeply moved by Banneker’s letter and accomplishments.  Jefferson wrote his own letter to the Marquis de Condorcet, and passed along to him Banneker’s almanac.  Jefferson’s letter to the Marquis de Condorcet states in part: “I have seen very elegant solutions of Geometrical problems by him … I shall be delighted to see these instances of moral eminence so multiplied as to prove that the want of talents observed in them [blacks] is merely the effect of their degraded condition [that is, slavery] and not proceeding from any difference in the stature of the parts on which intellect depends.”

Interestingly, Herschthal notes that “Jefferson’s [earlier] speculation about innate Black inferiority, published in Notes on the State of Virginia (1787), was at odds with mainstream scientific opinion … despite its often being seen, inaccurately, as representative of scientific ideas about race at the time.  In fact, until the early nineteenth century, environmentalism, and its assumption that all races were fundamentally equal, held sway … During the 1770s and early 1780s, explorers who traveled to Africa, regardless of their views on slavery, tended to discuss racial differences between Africans and Europeans in terms of culture, religion, and politics— in a word, character, not color.”

The notion that it was environment, not inherent inferiority, that explained any negative comparisons between races was exemplified by another prominent scientist Founder, Benjamin Rush, who was ushered into the network of the best scientists of the era by Benjamin Franklin.  Herschthal writes:

In 1766, a few years after graduating from the College of New Jersey (now Princeton University), Rush traveled to the University of Edinburgh, one of Europe’s leading medical schools, for his medical degree. Rush had not yet met Franklin, but he dedicated his dissertation to him and sent him a copy. Flattered, Franklin invited the twenty-three-year-old to London and introduced him to his prestigious network of scientific friends, men like Sir John Pringle, “then the favorite physician of the Queen,” as Rush recounted in his diary, and Dr. John Fothergill, the botanist and an architect of Sierra Leone. Franklin offered to pay for Rush’s subsequent trip to Paris, providing him letters of introduction to similarly renowned scientific figures in France, many of them known antislavery sympathizers, such as the chemist Antoine Baumé and the Versailles botanist Bernard de Jussieu. Upon meeting Jacques Barbeu-Dubourg, a physician and Franklin’s French translator, Rush noted in his memoir that Dubourg greeted him “in the following words: “Voila! Un ami de Mons. Franklin.” Franklin opened doors, and in the years to come, Rush would rely on these scientific networks to circulate his antislavery writings and tighten the links between abolitionists and men of science. Upon returning to Philadelphia in 1769, Rush was appointed professor of chemistry at the medical school of the future University of Pennsylvania. Three years later, [Anthony] Benezet asked Rush to write an essay in the movement’s behalf … Rush eagerly accepted his offer, and the resulting essay, An Address to the Inhabitants of the British Settlements, on the Slavery of the Negroes in America, published anonymously in 1773, was the first antislavery act— indeed, one of the first political acts— Rush ever took.  In An Address, Rush drew heavily on environmentalism, the dominant scientific explanation for racial difference, to refute planters’ claim that Africans were innately inferior and predisposed to slave labor. Environmentalism was rooted in natural history, though one of its core assumptions— that all races derived from a single human pair, or what historians call monogenism— came from the Bible. According to environmentalism, racial differences emerged as humans migrated across the globe, their bodies, customs, and mental habits changing in accordance with their new natural environments, or “climates,” as well as changes in the social environment. Yet while environmentalists assumed that all races were fundamentally equal, all equally human, they had no problem assigning certain physical and intellectual traits to individual “races.” The key difference between environmentalists and later nineteenth-century racial theorists was that environmentalists believed race was malleable, changing as people moved to new environments. Over time, Blacks could turn white, and whites Black, the theory supposed -- or, in a word, race was fluid, not fixed.  In An Address Rush argued that, whatever inferior traits enslaved Africans allegedly exhibited, slavery itself -- not anything innate to Black people -- could explain them … [Rush explained that Africa’s] vast terrain created insurmountable distances between people, making it difficult to establish organized governments; without proper government, he argued, civilization could not take root … [In contrast, in a 1798 essay,] Rush argued that Pennsylvania’s state government, in his view a shining example of yeoman republicanism, grew organically from the state’s natural environment. The colony’s first settlers entered a vast, disease-ridden forest, he wrote, but over time, they tamed the land and planted modest farms; eventually, the average Pennsylvania yeoman worked his own farm and became “a man of property and good character,” who “values the protection of laws” and “punctually pays his taxes towards the support of the government.” If farming the land oneself led naturally to responsible citizenship, then slave owning did just the opposite. As he wrote, Pennsylvanian farmers may “possess less refinement than their southern neighbours, who cultivate their land with slaves,” but “they possess more republican virtue.”

Movements to move slaves in America back to Africa were motivated in part to prove to the world that it was environment, not inherent inferiority, that was suppressing black progress:

For more than a decade, antislavery advocates in Britain and America had been floating the idea of establishing a free-labor colony in West Africa, worked by paid indigenous laborers and overseen by white officials, in the hopes that it would prove free-labor colonies in Africa could be more humane and more profitable than slave plantations in the Americas … In addition to proving that free Black labor could outperform enslaved labor, abolitionists argued, Sierra Leone’s commercial success would undermine the African slave trade by encouraging indigenous Africans to trade in “legitimate” goods rather than enslaved people … Conducted between 1788 and 1791, the hearings [in the British Parliament] focused on whether free-labor African colonies could undermine the slave trade in Africa, whether free- labor African colonies could be as profitable as Caribbean plantations, and whether they might one day function as replacements.

Herschthal also notes that:

By the 1790s slavery’s defenders increasingly argued that Africans’ barbarity, their “violent spirit of revenge,” doomed any attempt to impose “civilized” government on them. [Carl Bernhard] Wadström [a prominent abolitionist] countered that the political instability and violence sometimes witnessed in Africa arose from the slave trade itself. Indeed, the entire “state of anarchy and blood” that Wadström claimed characterized African societies stemmed from the pressure certain African groups felt to procure enslaved laborers for European slave traders. Though many nonscientific abolitionists also made this argument, Wadström lent it scientific legitimacy both as a firsthand witness and by embedding the claim in a work intended to read like a work of natural history.

(As explored in previous essays, much more recent research has tended to confirm the continuing negative effects the enslavement of blacks by African warlords has had on Africans to this day.)

So, as horrible as slavery was in America, and everywhere else it existed around the world, our country’s birth in the “Age of Reason,” and it’s founding document’s noble failure to protect a federal right to property in men, ultimately combined to end that most terrible institution, with the support of some of America’s most prominent early scientists.  As Herschthal summarizes, “By offering a wide range of scientific arguments against slavery, and relying on scientific networks to circulate their work and strengthen their ties to the movement, [Enlightenment-era scientists] began to make antislavery appear not just moral, but rational -- a movement backed by science.”