My hope [is] that we have not labored in vain, and that our experiment will still prove that men can be governed by reason.


We had no occasion to search into musty records, to hunt up royal parchments or to investigate the laws and institutions of a semi-barbarous ancestry. We appealed to those of nature, and found them engraved on our hearts.


On the Fourth of July, 1776, the day the Continental Congress adopted the Declaration of Independence, its author, Thomas Jefferson, took time on four occasions to record the local temperature. Consulting a portable thermometer, Jefferson noted that it was a comfortable 68 degrees at 6 a.m. in Philadelphia on that first Independence Day, rising to 72½ degrees at 9 a.m., 76 degrees at 1 p.m., and falling to 73½ degrees by nine in the evening. Jefferson did this as part of an ongoing research project aimed at tracking the air temperature, wind speed, barometric pressure, and other atmospheric phenomena, including displays of the aurora borealis, in as many locations as possible across the American colonies. He frequently importuned his fellow revolutionaries to collect their own data as well, so that weather maps could be drawn up for the entire eastern seaboard. (His most faithful meteorological correspondent was James Madison, later to succeed Jefferson as president, who promoted the metaphorical use of the word “barometer” to refer to social indices such as public opinion.) The idea was to advance meteorological science, so that farmers’ almanacs could be refined and weather forecasts improved.

All this was characteristic of Jefferson, who throughout his long career—he wrote the Declaration at age thirty-three and would live precisely fifty years longer, dying at Monticello on July 4, 1826—was a steadfast devotee of science and technology. Jefferson’s 1787 Notes on the State of Virginia, replete with references to Newtonian gravitation, was recognized as the best natural history treatise to have been written by an American. His work in agriculture, which he called “a science of the very first order,” culminated in his inventing an improved plow board based on Newton’s calculus of least resistance. To investigate the Virginia earthen barrows that he correctly hypothesized to be Indian burial mounds, Jefferson invented a method of stratigraphic excavation still employed by geologists today. (He also compiled what was at the time the world’s most extensive compendium of American Indian vocabularies.) He read the classical philosophers in the original Greek and Latin but regarded Bacon, Locke, and Newton as superior to them all, commissioning a group portrait of the three and advising the artist, “I would wish to form them into a knot on the same canvas, that they may not be confounded at all with the herd of other great men.” While recognizing science to be the sole source of what he called “sure knowledge,” Jefferson had a scientist’s caution about the errors present in every observation. Timing the solar eclipse of September 17, 1811, through his telescope at Monticello, he noted that while the timed intervals might be internally accurate with regard to one another, he had “no confidence” that his clocks were accurate enough to yield the absolute time of the eclipse. A modern computer analysis shows that Jefferson was right on both points: His overall times, hindered by his difficulty in setting his clocks against transits of the sun across the local meridian, were off by several minutes, but his internal values—such as the interval between the onset of the eclipse and the moment when the moon was directly centered on the sun—were accurate to within 10 percent.

Fascinated by technology, Jefferson traveled with a pocket telescope, fitted his carriage with an odometer that rang a bell to mark each mile, tinkered with a document copier (and complained about the poor quality of its “fetid” copy paper), invented a cipher machine still being used in the twentieth century, and served his dinner guests at Monticello from a set of dumbwaiters modeled on those of the Café Mécanique in Paris. He prescribed a national system of weights and measures, headed up the patent office, and wrote the first scientific paper (his “Report on Desalination of Seawater” of November 1791) to be published under U.S. government auspices.

Jefferson often said that he valued science over statecraft—“Science is my passion, politics my duty”—and his behavior bore him out. Elected vice president in 1797, he tarried at Monticello to study the bones of a prehistoric ground sloth sent him by the frontier scout John Stuart, journeying to his own inauguration only once political opponents began to cite the delay as evidence of haughtiness. He brought the bones along to Philadelphia, presenting them on March 3 to the American Philosophical Society, a scientific body which made him its president, an honor he pronounced to be “the most flattering incident of my life.” On the following day he finally got around to taking the oath of office as vice president of the United States.

While serving in that post he reported to his daughter Martha that he was “abandoning the rich and declining their dinners and parties” in order to consort “entirely with the class of science, of whom there is a valuable society here.” During the bitter presidential contest of 1800, when Jefferson and Aaron Burr remained deadlocked in the House of Representatives through thirty-five ballots over the course of eight anguished days, Jefferson stayed out of the fray, preferring to investigate whether the full moon influences terrestrial climates. (It does not.) As president it was his custom to ride into the countryside on horseback in the mornings, collecting botanical cuttings along the Potomac: A white-flowered herb, Jeffersonia binata, is named in his honor. He worked at his desk with a pet mockingbird perched on his shoulder—the bird would hop up the stairs after him when he went to bed—and conducted animal husbandry experiments that involved keeping a pair of grizzly bears and a flock of Merino sheep on the White House lawn. A veteran who came to the White House seeking a pension complained of being “attacked and severely wounded and bruised by your excellency’s ram.”

“Nature intended me for the tranquil pursuits of science, by rendering them my supreme delight,” Jefferson wrote shortly after leaving office, “but the enormities of the times in which I have lived, have forced me to take part in resisting them, and to commit myself on the boisterous ocean of political passions.” He said that what he valued most in public service was the opportunity to advance learning and liberty. His self-composed epitaph describes him as “Author of the Declaration of American Independence, Founder of the University of Virginia, and Author of the Virginia Statute on Religious Freedom,” but makes no mention of his having been governor of Virginia and president of the United States.

The Declaration of Independence, which Jefferson drafted in Jacob Graff’s rooming house on a portable desk of his own design, is steeped in the language of science and of the Enlightenment philosophers inspired by science. The reference in its first sentence to “the laws of nature and of nature’s God” echoes Descartes’ “laws of motion” and Newton’s “laws of nature.” Its second sentence asserts as “self-evident” certain “truths,” among them that all men are created equal and are endowed with inherent and inalienable rights such as life, liberty, and the pursuit of happiness. The term “self-evident” apparently was inserted by Benjamin Franklin, to whom Jefferson had submitted his draft for review—Jefferson had written “sacred and undeniable”—and its effect was to shift the argument toward a grounding in science and mathematics. Franklin and Jefferson would have first encountered the term “self-evident” in the axioms of Euclid’s geometry, which in those days was usually taught from a popular textbook prepared by Isaac Newton’s teacher Isaac Barrow.* It showed up as well in lectures on oratory composed by the English chemist Joseph Priestley, who was a friend of both Jefferson and Franklin, and in the first alphabetical encyclopedia published in English—John Harris’s Lexicon Technicum, a copy of which Jefferson had in his library—where science is described as being founded on “self-evident principles.” John Locke composed an essay on self-evident axioms in mathematics and mathematical science. “In all sorts of Reasoning,” he wrote, “every single Argument should be managed as a Mathematical Demonstration.” Jefferson echoed Locke so strikingly in the Declaration that he eventually felt obliged to maintain that he had not been imitating Locke and had indeed “turned to neither book nor pamphlet while writing it.”

The Declaration is structured as a syllogism. Its major premise asserts as axiomatic that people may “alter or abolish” a government that denies them human rights. Its minor premise is that King George has been guilty of just such conduct: “To prove this let facts be submitted to a candid world.” Its conclusion is that the colonies are thereby justified in severing their ties with England. As an example of clear reasoning this would have pleased Jefferson’s teacher William Small, a Scottish mathematician who taught rhetoric, logic, and natural philosophy at the College of William and Mary. Jefferson remembered Small as “a man profound in most of the useful branches of science, with a happy talent of communication…& an enlarged & liberal mind,” adding, “From his conversation I got my first views of the expansion of science & of the system of things in which we are placed.” Along with a devotion to science and liberty, Small brought with him from Scotland a cleanly composed logic book written by his teacher William Duncan, a self-taught journalist, classicist, and science professor so admired by his students at Marischal College, Aberdeen, that they chipped in to equip his physics laboratory. Drawing on the thoughts of “the great Mr. Locke,” Duncan taught that science is the soundest method of discovery, and that arguments ought therefore to begin with perception and proceed through reasoned judgment to demonstration. (These “demonstrations” might take the form of either scientific experimentation or mathematical reasoning.) The first example of a syllogism in Duncan’s Logic is not the old, “All men are mortal; Socrates is a man;…” but the assertion of a “self-evident” link between reason and human rights:

Every creature possessed of reason and liberty is accountable for his actions.

Man is a creature possessed of reason and liberty.

Therefore, man is accountable for his actions.

The lasting appeal of the Declaration of Independence arose in part from Jefferson’s having firmly grounded it in mathematics, science, and logic. As the Princeton University rhetoric professor Wilbur Samuel Howell observes, the ideas set forth in the Declaration “were given added persuasive power by their adherence to the best contemporary standards of mathematical and scientific demonstration and what the best contemporary thinkers expected of proof before it could claim to convince the reason.” Abraham Lincoln believed the Declaration to be “applicable to all men and all times,” adding, “I have never had a feeling politically that did not spring from the sentiments embodied in the Declaration of Independence.”

Granted, Jefferson was an extraordinary individual; the dark waters of his intellect run so deep that his biographers, like Isaac Newton’s, have complained after years of labor that their scholarly bathyspheres never did touch bottom. Jefferson’s library was sufficiently commodious—he read not only Greek and Latin (“a sublime luxury”) but Old English, French, Italian, and a smattering of German—that when the Library of Congress was put to the torch by British troops in 1814, he was able to reestablish it by shipping six thousand of his own books to the Capitol. His papers and correspondence, publication of which has been going on for decades in an edition expected to run to some sixty volumes, reflect a penetrating interest in everything from astronomy, biology, horticulture, history, philosophy, and law to the military applications of submarines armed with torpedoes. A close reader of the Bible, Jefferson agreed with Thomas Paine that biblical tales of the supernatural had the effect of “degrading the Almighty into the character of a showman, playing tricks to amuse and make the people stare and wonder” accordingly he produced what is known today as the “Jefferson Bible,” a New Testament stripped of mysticism and miracles. When a student asked for advice on how best to pursue his studies, Jefferson replied that a knowledge of “astronomy, botany, chemistry, natural philosophy, natural history [and] anatomy…is necessary for our character as well as comfort” and that trigonometry “is most valuable to every man [as] there is scarcely a day in which he will not resort to it for some of the purposes of common life,” whereas higher mathematics, such as “spherical trigonometry, algebraical operations beyond the 2d dimension, and fluxions”—Newton’s term for differential calculus—are “a delicious luxury indeed” but not essential to a liberal education. Discerning a mathematical problem in the Constitution’s approach to apportioning congressional districts on the basis of population, Jefferson devised a way to solve it: Known to mathematicians today as the “method of d’Hondt,” it anticipated by many years its independent discovery by the Belgian mathematician and attorney Victor d’Hondt in 1878. President John F. Kennedy was not exaggerating when he toasted a gathering of forty-nine Nobel laureates by describing them as comprising “the most extraordinary collection of talent, of human knowledge, that has ever been gathered together at the White House, with the possible exception of when Thomas Jefferson dined alone.”

Jefferson was not alone among the founders in his devotion to science. George Washington was no scientist—his formal education ended at about age fifteen, and by his early twenties he was fighting in the French and Indian War—but he had a sturdily empirical habit of learning from experience and a lifelong scientific curiosity that shone out from the depths of his monumentally composed personality. Having learned mathematics as a surveyor, Washington conducted agricultural experiments at Mount Vernon, designed and tested a new variety of plow, dispatched rare birds for study at Philadelphia’s new natural history museum, and offered to send soldiers to help excavate a mastodon discovered near Newburgh, New York, in 1801. Washington couldn’t even order a sleigh without inquiring whether, “upon philosophical, mechanical, or practical principles, is it best to have the sliders (excepting always the curve in front) a little circular, or quite straight? The longer the bearing the greater the friction; the shorter, the weight is confined to a smaller space of the sliders, and consequently the compressure greater….” Ever the objective observer, Washington is said to have been taking his own pulse at the moment when he died. John Adams, America’s second president, studied physics at Harvard under the astronomer John Winthrop, helped found the American Academy of Arts and Sciences—in Boston, where, he said, “I knew there was as much love of science, and as many gentlemen capable of pursuing it [as may be found in] any other city of its size”—and lamented in a letter to Jefferson that he should have spent more time in scientific pursuits: “Oh that I had devoted to Newton and his fellows that time which I fear has been wasted on Plato and Aristotle [and] twenty others upon subjects which mankind is determined never to understand, and those who do understand them are resolved never to practice.” Dr. Benjamin Rush of Pennsylvania, an influential founder who served as treasurer in the Adams administration, was a chemistry professor and epidemiologist who wrote the first American textbook on psychiatry and pioneered the treatment of alcoholism as a disease. Roger Sherman, a signer for Connecticut described by Jefferson as “a man who never said a foolish thing in his life,” was a sufficiently capable astronomer to have done the celestial calculations for a colonial almanac. And Benjamin Franklin, who soothed Jefferson’s temper while the delegates deleted his denunciations of slavery from his draft of the Declaration, was America’s foremost scientist.

In drafting the Constitution, the founders again had frequent recourse to scientific language, logic, and metaphor. John Adams consulted Newton’s laws of motion for ideas on how to structure the Constitution. James Madison, its principal author, declared, “Liberty is to faction what air is to fire…but it could not be less folly to abolish liberty, which is essential to political life, because it nourishes faction, than it would be to wish the annihilation of air.” The founders also drew on the thinking of scientifically inclined English thinkers like the seventeenth-century political philosopher James Harrington and the eighteenth-century colonial governor Thomas Pownall. Harrington had studied democratic precepts during an extended stay in the Venetian Republic; his utopian book Oceana compared the “political anatomy” of a bicameral legislature with the circulation of blood through the human heart discovered by William Harvey: “The Parliament is the heart, which, consisting of two ventricles, the one greater and replenished with a grosser matter, the other less and full of a purer, sucks in and spouts forth the vital blood of Oceana.” Pownall, a close friend of Benjamin Franklin’s, envisioned a future political science “that might become Principia to the knowledge of politick operations.” A free-trade internationalist, Pownall argued that it was in England’s economic interest to grant freedom to its American colonies, since “North-America is become a new primary planet in the system of the world,” and will “shift the common center of gravity of the whole system of the European world.”

The founders viewed science as an engine that could make posterity healthier and wealthier, to be sure, but also freer; and since freedom is both good in itself and a promoter of betterment, they anticipated that humanity might be improved as the light of science and liberty spread across a benighted world. As Jefferson put it, “The progress of science offers to increase the comforts, enlarge the understanding, and improve the morality of mankind.” These were not just pipe dreams but hardheaded political calculations that have in many ways been borne out in the shaping of the modern world. What, exactly, did they have in mind?

The practical potential of scientific research—the process of applying science to technology and, in turn, using the new technology to improve scientific tools—was by the eighteenth century clear enough to those who cared to read its handwriting on the wall. Jethro Tull’s seed drill, invented in 1701, sharply reduced the cost of food. Improved iron and steel was being produced, owing to the innovations of Abraham Darby (coke smelting, from 1709) and Benjamin Huntsman (crucible steelmaking, from 1740). Steam-driven pumps drew water out of mine shafts, enabling coal miners to dig to unprecedented depths, while John Kay’s “flying shuttle” for faster weaving brought boom times to the textile industry. The decrepit state of European and American internal transportation was beginning to yield to innovations such as England’s growing network of canals (hastened by the Canal Act of 1759) and Pierre Trosanquet’s road-building efforts in France. It required no great discernment to anticipate the value of improved technology to international economic competition. The feedback loop of the modern world—in which nations that nourish scientific research reap material rewards that increase their wealth and power, leading to further scientific and technological progress and even greater wealth and power—had begun to stir into action.

Technological innovation put cash in the pockets of persons excluded from such traditional sources of prosperity as inherited land and titles, creating a social mobility that undermined old political structures and strictures. Applied science amplified and accelerated the pace of technological progress, offering not only a source of labor-saving devices in the home—a better loom or plow, a more helpful farmer’s almanac—but a way to make money and move up in the world. Alexis de Tocqueville viewed this dynamic as central to the American character: “Once works of the intelligence became sources of power and wealth, people were obliged to look upon every scientific advance, every new discovery and idea, as a germ of power placed within the people’s grasp.” For those who disdained materialistic motives—arguing that knowledge should be pursued as an end in itself, rather than as a gateway to power and wealth—Tocqueville had two rebuttals. First, it’s not all that clear that pure science is somehow superior to applied science, Tocqueville suspecting that the intellectuals’ habit of esteeming the abstract over the concrete was anachronistic. “Permanent inequality of conditions encourages men to limit themselves to the proud and sterile search for abstract truths,” he wrote, “whereas the democratic social state and institutions encourage them to look to science only for its immediate and useful applications.” Second, pure science benefits from the growth of applied science regardless of whether that growth is impelled by a desire for power rather than knowledge: