The Reading Room

John Locke and the New Course of Enlightenment Reason: Empiricism

The world hardly needs another brief introduction to the giant of English philosophy, John Locke. He could be called the author of the Western mind. And has been called the quintessential man of the Enlightenment, the “father of true liberalism,” and the pioneer of empiricism in science. George Washington described him more succinctly as “the greatest man who . . . ever lived.”
His contributions to philosophy were vast and varied but underlying them is a momentous break with the past—although not one attributable to Locke alone. The men who set philosophy’s new direction as Europe emerged from the Middle Ages and Scholasticism came to be called “rationalists.” Reasoning meant identifying first premises (e.g., “I think, therefore I am”) and deducing from them, by logic, an entire philosophical structure. Réné Descartes, Benedict Spinoza, and Wilhelm Leibniz were the towering figures in the rationalist school—at the core of Western philosophy’s story.
It is perhaps no accident that John Locke viewed himself not primarily as a philosopher, mathematician, or theologian but as a physician and medical investigator. The natural sciences do not and cannot proceed by logical deduction from accepted premises. He warned: “No man's knowledge here can go beyond his experience.”
Isaac Newton, a physicist, and Locke, a physician-scientist, approached knowledge as observers—as empiricists—and decisively influenced the emergence of empiricism in contrast with rationalism. The scientific revolution, of course, already had introduced and succeeded with the methods of observation and experimentation. But Locke turned Western philosophy in the direction of empiricism—changing the world forever. If Locke’s philosophy were to be inscribed on a banner, it might be: “Nothing is in the intellect that was not first in the senses.” 
His Two Treatises on Government (1689) expounds arguments for natural law and what it tells us about morality and human rights, the state of nature and the social contract, the legitimate organization of society and government, and the nature and justification of property—among much else. Every principle and argument is part of the intellectual capital of Western culture (and beyond), beginning with Locke’s inspiration of the new American republic’s constitution and government.
His Essay concerning Human Understanding (1689), equally ambitious in its scope, has been no less influential in its domain than the Treatises. Locke constructs a theory, based upon observation of man’s capacity for understanding and knowledge and how they are achieved. His refutation of the existence of innate ideas; his concept of “ideas” and how the mind creates and uses them; his concept of primary and secondary qualities known by the human senses; his theory of personal identity; his discussion of the role of language; and his definition of the nature, standards, and extent of human knowledge: all changed the course of philosophy and set its directions for the future. 
An example: “The acts of the mind, wherein it exerts its power over simple ideas, are chiefly these three: 1. Combining several simple ideas into one compound one, and thus all complex ideas are made. 2. The second is bringing two ideas, whether simple or complex, together, and setting them by one another so as to take a view of them at once, without uniting them into one, by which it gets all its ideas of relations. 3. The third is separating them from all other ideas that accompany them in their real existence: this is called abstraction, and thus all its general ideas are made.” 
These are empirical conclusions derived entirely from observation—specifically from introspection. From the laboratory of Locke’s own mind. He is reaching conclusions in epistemology as he did in medicine, by observing reality.
Note, first, that Locke (1632-1704) had finished his work and died just two decades into the period historians define as the Enlightenment. Isaac Newton and John Toland, the Irish deist, also fall into this pre-Enlightenment category. Newton and Locke set the terms of the Enlightenment in science, natural law, politics, the theory of knowledge, religion, and much else. 
Born in Somerset (southwest England, bordering the Bristol Channel) to a prosperous professional family, Locke grew up in England’s most tumultuous political times. His family sympathized with Puritanism but stayed with the established Anglican Church of England. John was only ten when the English Civil War[s] began between Charles I and Parliament, whose forces came under the dictation of Oliver Cromwell. Locke’s father, a lawyer and ardent Puritan, served with Cromwell’s parliamentary forces as a captain of horse.
At fourteen, Locke enrolled in the prestigious Westminster School, now taken over by the Cromwell forces. In 1649, he was among the boys at school denied attendance at the execution of Charles I, just half a mile away. Locke remained a political man all his life, both in government affairs and his philosophy, credited with inspiring the American Revolution of 1776 and the French Revolution of 1789.
Locke entered the University of Oxford’s largest college, Christ Church, in 1652. It had been a base of Charles I during the war but now was dominated by Cromwellians. Just as did Adam Smith, attending Balliol College a century later, Locke found Oxford dull and uninspiring. It remained, at that time, a medieval university, teaching the philosophy of Aristotle, with little attention to the new ideas about the knowledge of thinkers like Francis Bacon and Réné Descartes. And, like Adam Smith, Locke spent his time in the library studying on his own the new empiricism of scientific investigation.
Locke got his bachelor’s degree in 1656, and a master’s degree two years later, and became a fellow of Christ Church. There he met great advocates of Enlightenment science, but, above all, the one who had the most influence was the scientist (then called a “philosopher and theologian”) Robert Boyle, who became his research collaborator. This collaboration channeled Locke into medicine, which became his career, practiced even as he wrote on philosophy.
In 1660, the restoration of the English monarchy shook Locke’s life again. His Oxford scientific collaborators departed for London, where they founded the Royal Society, and, at Oxford, freedom from Puritan control unleashed among undergraduates every excess, including religious “enthusiasm.” It left Locke with a lifelong caution about abrupt social change. It was but another lesson in social and political upheaval. Locke came to intellectual grips with the issue in his first substantial work, Two Tracts on Government, which he finished in 1660 but which did not get published for a full three centuries (in 1967). It cannot be considered, therefore, part of his influence on the Enlightenment.
We know now that this first systematic formulation of Locke’s ideas defended conservatism in the name of political stability—not surprising, given his experiences since boyhood. For instance, he rationalized government legislation on religion (within the boundaries of Christian beliefs) to counter the anarchy arising from sectarian conflict. But when he published Two Treatises on Government decades later (1689) he had moved 180 degrees into opposition to his earlier position.
Now, a pattern emerges. Locke became a senior censor (a kind of academic administrator) in Christ Church, supervising and disciplining undergraduates and giving lectures. From his lectures came Essays on the Law of Nature, written in 1663—but, again, not published until 1954. Although Locke did not change the views he formulated there, it seems likely that he was writing as a way of thinking [personal aside: what other way is there?], but not prepared to serve possibly half-baked ideas to the public. This reflects a rare maturity and restraint for a man Locke’s age.
In that essay, Locke formulated his views on a “law of nature”—a natural moral law from which we can judge the rightness or wrongness of human choices and actions. He likewise formulated, here, the “empiricist principle” that all knowledge (including a moral code) is derived from experience. More than any other philosopher, John Locke is credited with banishing the doctrine of innate (in-born) ideas from philosophy. 
Although that essay was withheld from publication, the ideas expressed by Locke—natural law with its implication for political theory (e.g., natural rights) and empiricism with its implications for epistemology—are at the core of Locke’s mature philosophy. 
At Christ Church, Locke came to the attention of a powerful political figure of the time, Lord Anthony Ashley Cooper, who became first Earl of Shaftesbury. Locke became a member of Shaftesbury's household in Exeter as his personal secretary and physician. The direction of causality, here, is uncertain. Shaftesbury's convictions were for a constitutional monarchy, a Protestant succession, civil liberty, religious tolerance, supremacy of Parliament, and national economic growth. Did Locke arrive already sharing those views, or did he adopt them from Shaftesbury? The choices are not mutually exclusive. In any case, a profound mutuality developed between the men.
Shaftesbury was a political force in England, a leader of the Whigs. Locke seems to have drafted position statements and speeches for him. And, as a physician, Locke conceived and carried out a remarkably successful new operation on Shaftesbury to permanently relieve the pressure and pain of a tumor. His education complete, his position as physician and political collaborator with the Earl of Shaftesbury secure, Locke turned to writing and publishing the books on epistemology, morality, and politics that together changed the course of ideas and of history for centuries to come.