over external authority, their adherents included some of the greatest minds of the age, including Isaac Newton.
Newton provides an example of how the idea of “science” had not yet fully emerged as something separate from religion in early Enlightenment thinking. In fact, during the seventeenth century, the word “scientist” was not commonly used to describe experimenters at all; they were called “natural philosophers,” an extension of the Puritan idea of the study of the Book of Nature. Science had also not fully emerged as a separate concept, but was sometimes thought of as a method or style of study in the arts, rather than a discretely defined set of disciplines. This was true even into Thomas Jefferson’s day. Jefferson himself usually used the word to mean what today we call the hard sciences, but sometimes he used it to refer simply to the rigorous study of other fields, such as the “sciences” of language, mathematics, and philosophy.
By 1663, a time when Puritans were a decided minority in England, 62 percent of the natural philosophers of the famed Royal Society of London were Puritans, including Newton, who had studied Ibn al-Haytham’s work on light and refraction, and who wrote far more on religion and alchemy than he did on science. Newton believed in the inerrancy of scripture, biblical prophecy, and that the apocalypse would come in 2060. He was “not the first of the age of reason. He was the last of the magicians,” said economist John Maynard Keynes, who purchased a collection of Newton’s papers in 1936 and was astounded to find more than one million words on alchemy and four million on theology, dwarfing his scientific work. Newton went on to create calculus and to publish Philosophiae Naturalis Principia Mathematica, or Mathematical Principles of Natural Philosophy (today, Mathematical Principles of Science), upon which modern physics was founded.
Eighty-nine years later, Principia was one of the main sources Thomas Jefferson drew upon for inspiration as he sat in the two second-story rooms he had rented from Jacob Graff in Philadelphia, writing the Declaration of Independence.
The Scientist-Politician
Racked by the threat of war and with its political power resting on uncertain ground, in June 1776 the Continental Congress appointed Jefferson, along with Benjamin Franklin, John Adams, Roger Sherman, and Robert Livingston to secretly draft the document. The committee delegated the writing of the first draft to Jefferson.
Like Bacon, who had died of pneumonia after conducting an experiment on preserving meat with snow, Jefferson was both an accomplished attorney and a passionate scientist. On July 4, 1776, the day the Continental Congress eventually adopted the Declaration of Independence, Jefferson took the time to record the local temperature on four separate occasions as part of a broader research project he was conducting. His measurements typically also included barometric pressure and wind speed. His goal was to improve meteorological science to refine farmer’s almanacs and improve weather forecasting throughout the colonies, both of which were of personal importance to Jefferson as a farmer.
Jefferson also had knowledge of physics, mechanics, anatomy, architecture, botany, archeology, paleontology, and civil engineering. He was an avid astronomer. He carried a small telescope with him wherever he went and recorded the eclipse of 1778 with great precision, although he was frustrated by the cloudy conditions. As president, he commissioned the Lewis and Clark expedition. He sold it to Congress as an economic initiative, but he sent his presidential secretary, Meriwether Lewis, for training with the top scientists of the day and instructed him to conduct it as a scientific expedition.
Jefferson’s love of science is well known among students of science policy. “Science is my passion, politics my duty,” he said. In writing to a friend just prior to the end of his term as president of the United States, he said,
Never did a prisoner, released from his chains, feel such relief as I shall on shaking off the shackles of power. Nature intended me for the tranquil pursuits of science, by rendering them my supreme delight, but the enormity of the times in which I have lived, has forced me to take part in resisting them, and to commit myself to the boisterous ocean of political passions.
Jefferson was also very familiar with Coke, whose Institutes he had studied as a law student. This heady mix of science, law, and politics, and the idea of circumscribing the power of the monarch, would lead Jefferson to carve out a founding document for the United States that was based not on religion or God, but on knowledge and reason. Whereas religious authority and proximity to God could be endlessly argued between different faiths or countries, Jefferson reasoned that a country based on the more narrowly defined rule of men—a democracy—was removed from this, freeing both religion and the government. This being the Enlightenment, Jefferson needed to convince the world’s nations that American independence should be respected as rational and correct, and that they should not intercede in the revolution, so he had to build the most inspiring and unassailable Enlightenment argument possible. As his friend and advisor Benjamin Franklin later noted dryly after signing the declaration Jefferson would craft, “We must all hang together or most assuredly we will all hang separately.” Their very lives would depend on the quality of Jefferson’s argument.
How Do We Know Things?
Holed up in his rented rooms, faced with this awesome responsibility, the thirty-three-year-old took up his quill pen. He considered Francis Bacon, Isaac Newton, and John Locke, whom he had studied at the College of William and Mary, to be the three most important thinkers of all time. He called them “my trinity of the three greatest men the world had ever produced.” Writing on a portable “lap desk” of his own design, he labored to create a document that reflected the clear, axiomatic logic of John Locke, who instructed that “in all sorts of reasoning, every single Argument should be managed as a mathematical demonstration; where the connexion of ideas must be followed till the mind is brought to the source on which it bottoms.” Bottoming his argument out on an irrefutable foundation was what Jefferson needed to do to avoid hanging.
Like Newton and Bacon, Locke was an Englishman and a Protestant, and he is credited with creating the philosophy of empiricism, on which much of modern science is based. He divided human thought into two categories: knowledge and belief. Locke was aware of the many divisions within Christianity, with each faith arguing that it was the one true religion. This was true not only of the great divide between Protestantism and Catholicism, but also of lesser divides between German Lutheranism and English Protestantism, as well as between the Church of England and the dissenters: the Puritans, and within them the sects of Presbyterians, separatist Congregationalists (from whose congregations came the American Pilgrims), and Baptists. Each could not be the one true religion, so some method of ascertaining truth or falsehood had to be developed, or the conflicting claims were likely to go on forever. This led him to ask some fundamental questions: How do we know something to be true? What is the basis of knowledge?
Locke’s An Essay Concerning Human Understanding, published in 1689, just two years after Newton’s Principia, strove to answer that question, by laying out what can be known empirically, how it is that we know it, and the inherent limits of knowledge. He began, building on Bacon and Ibn al-Haytham, whom he, too, had studied, with observation of the natural world. He then divided knowledge into three types: intuitive, demonstrative, and sensitive.
Intuitive knowledge is “self-evident” to anyone looking at it, and it carries the least doubt of the three types of knowledge. Three is more than two, black is not white, and the presence or absence of a thing are examples of intuitive knowledge.
Demonstrative knowledge, the second type of knowledge, is slightly less certain than intuitive knowledge. Agreement or disagreement is not immediately clear, but instead depends on the use of reason to demonstrate “by necessary consequences, as incontestable as those in mathematics,” that something is so. Each step in a reasoning process—which, as St. Germain had described, was the process of discovering the natural law of things—must in and of itself be intuitively evident. For example:
I can show you using these two apples in my left hands and these two apples in my right hand that two plus two equals four.
or:
A feather falls more slowly in air than a penny does. When we remove the air with a vacuum pump, the feather and the penny fall at the same rate. Therefore,