David Hume: Skepticism, Pessimism, Enlightenment

“The identity that we ascribe to things is only a fictitious one, established by the mind, not a peculiar nature belonging to what we’re talking about.”—David Hume

David Hume (1711–1776), whose life spanned much of the “long eighteenth century” (although he missed both the American and French Revolutions), is a giant of the Age of Enlightenment. And that is irrespective of whether you view him as a destructive skeptic of all Enlightenment principles or a man demanding of his age the logical consistency that it boasted. If there is a single mnemonic tag for Hume, it is “skeptic.” He disputed all ideas and ideologies not rooted in direct experience. In that sense, he is the conscience of the Age of Enlightenment and its advocacy—with many lamentable concessions and compromises to appease theology—of rooting all knowledge in immediate experience.  

A man of the Scottish Enlightenment, he wrote beautifully, published both history and philosophy, was so skeptical that he was viewed as atheistic, and is the chief link (via the work of Immanuel Kant) between the Scottish/English/French Enlightenment and the final phase of the Enlightenment in Germany. His impact on the German Enlightenment is captured in a famous quotation in philosophy, when Immanuel Kant (1724–1804) wrote that reading Hume had woken him from his “dogmatic slumbers.” And the apostle of utilitarianism, Jeremy Bentham (1748–1832), wrote similarly that Hume “caused the scales to fall” from his eyes. Darwin asserted that the ideas and methods of Hume were vital to reaching his theory of evolution. Not until Darwin published his theory of evolution did the “argument from design,” the essence of the “natural theology” of the eighteenth century (and the target of one of Hume’s most famous works of philosophy), give up the ghost.

In other words, Hume, more than any other Enlightenment philosopher, except possibly John Locke, influenced philosophers to come. It is crucial to pause here. Hume’s influence through Kant and the German idealist tradition has shaped philosophy to this day—most recently via the postmodernist movement and what in the United States today we call extreme “political correctness.”

But John Locke and others of the Enlightenment’s “new philosophers” represent a very different philosophical influence that informed the Declaration of Independence and the U.S. Constitution and its Bill of Rights. That influence shaped the reality of the American nineteenth century, in which the U.S. economy became the world’s largest. This was the real-world result of Enlightenment philosophy, broadly and generally. Reason, the separation of church and state, individualism, science and innovation, the ideas of Adam Smith, the revolution in legal and penal theory of Cesare Beccaria: all shaped the new American republic and its example for the world.

David Hume’s thought shaped and directed the later Enlightenment’s radically skeptical epistemological development, advancing more slowly than Locke’s impact on America, and with the practical effects of his thought delayed by decades and centuries. Effects we are now experiencing in America. 

Hume was born in Edinburgh in the Scottish lowlands; he was of “good family,” though not wealthy. As an infant, he lost his father but reportedly had a devoted mother. Reading between the lines, it seems the precocious David became “a handful,” and when his older brother headed off for the University of Edinburgh, David, then only ten, went with him. There, the boy plunged into Latin and Greek; he read history and literature and ancient and modern philosophy and delved into mathematics and natural philosophy (i.e., science). Understand that the official goal of all this education was to inculcate the principles of a life of virtue as defined by Scottish Calvinism. Prayers and sermons were part of every day. 

The ideal career for a young man in Scotland at this period was a ministry in the established Church of Scotland (the original direction also chosen for Adam Smith). Hume’s family perceptively thought that the better choice for David was law. Hume pronounced law “nauseous” and announced he would be a “scholar and philosopher.” And that is what he became—and changed the history of thought.

Hume had a theoretical ferocity in his philosophical speculation, as we shall see, and, at the same time, a most sensible approach to living life. With the meager inheritance of a second son, he went to live in France, living cheaply in a little village in Anjou and devouring the works of French and other continental thinkers like Malebranche, Dubos, and Bayle. By now, he had rejected his religion and had become an antagonist of organized religion. That never changed for Hume. And his initial statement of it in A Treatise of Human Nature (which he began when he was only twenty-three) prevented him for the rest of his life from getting any appointment to the faculty of a university. It is the price that David Hume paid for what he viewed as logical consistency: drawing the conclusions (for example, about certainty or religion) implied but not drawn by earlier thinkers.

Not that he refused to be “practical.” Returning to England with his manuscript for the Treatise, ready to prepare it for the press, he made many compromises (“castrated” his manuscript, he said) and published it anonymously. It availed him not. He claimed that the book fell “dead born from the press,” but it attracted enough attention to leave him with a lifelong reputation as an atheist. His applications for university chairs at Edinburgh and Glasgow were rejected. Arguably the most influential philosopher of his time, he never held an academic post.

Hume supported himself as a tutor, a diplomatic secretary traveling in Austria and Italy, and then as a librarian to the University of Edinburgh Faculty of Advocates. He wrote his famous History of England, tracing the origin of its liberties. He was a close friend of Adam Smith, also in Edinburgh, and, like Smith, wrote essays advocating free trade. In 1748, the peak of the Enlightenment, Hume turned out book after book: first, An Enquiry Concerning Human Understanding; in 1751, he published An Enquiry Concerning the Principles of Morals. More essays and the Political Discourses appeared in 1752, and Hume’s correspondence reveals that a draft of the Dialogues Concerning Natural Religion was also under way at this time (out of his practical prudence, Hume arranged for it to be published after his death).

His appointment as librarian at the Edinburgh Faculty of Advocates gave him an opportunity to write his History of England. It won him financial independence and remained a bestseller into the nineteenth century.  He had more independence, but his reputation as an atheist continually dogged him; his friends and his publisher responded by persuading him, as noted above, to suppress his controversial writings on religion—at least until he died.

Now, he traveled to France as private secretary to the British ambassador, and for three years in Paris he was the rage of the salons and came to know, and be known among, European intellectuals. Reportedly, he loved good food and wine and the company of women. 

Back in Edinburgh by 1769, he built a house and passed his last years dining and conversing with friends, revising his books to prepare new editions. He prepared for publication his Dialogues Concerning Natural Religion. It is perhaps the singular “go to” source, today, of refutations of arguments for the existence of God. Published in his lifetime, it likely would have destroyed Hume; published after his death, it has gone far to destroy attempts to argue for God’s existence in the name of reason.

His end came soon after, in 1776, from intestinal cancer. Many had expected, hoped, and predicted that David Hume, the “great infidel,” would repent on his deathbed and call for the last rites of the church. All reports from his friends are that he approached death with the peaceful cheer that he had brought to life.

Even to summarize Hume’s arguments would require many pages. He idolized Isaac Newton (not unusual, then) and adopted his methods. But Hume’s subject was human nature, by which he meant the mind, its connection to reality (if any), its operating parts (impressions, ideas, associations, beliefs), and what constituted knowledge. 

Always returning to Newton, Hume insisted that our only knowledge is from experience. We know nothing else. And he thought the whole history of philosophy had been captive to speculation—the thickets of metaphysics. As a result, philosophy for centuries had wrangled over the same metaphysical questions—and gotten nowhere. He asked (and answered his own question): “If we take in our hand any volume; of divinity or school metaphysics, for instance; let us ask, Does it contain any abstract reasoning concerning quantity or number? No. Does it contain any experimental reasoning concerning matters of fact and existence? No. Commit it then to the flames: for it can contain nothing but sophistry and illusion.”

To enormously compress things, here, Hume examined the faculties and functions of the mind, always asking what we know by experience, and concluded we can know nothing about reality. Like virtually all the Enlightenment’s “new philosophers,” Hume talked in terms of “ideas”—the actual contents of our minds. Locke had discussed how these were our means of knowing “reality.” George Berkeley said we know only ideas, not if they represent reality, but we know that they are consistent and dependable because of God. Hume said Berkeley is right. We know only our “impressions” and “ideas,” but we cannot bring God into the equation. That is metaphysics. Not science. And without science, we never will reach valid conclusions.

Thus, David Hume pronounced the ultimate verdict of Enlightenment epistemology, capping the Locke-Berkeley-Hume logical progression. No theory of reality is possible. We can know nothing beyond our immediate experience, which is of impressions and ideas. We cannot know what Immanuel Kant—inheritor of the British and Scottish Enlightenment impasse—called the “Ding an sich”—the “thing in itself.”

In epistemology (the theory of knowledge), then, Hume represented the logical conclusion of Enlightenment thought. Holding his predecessors, from Descartes to Leibniz, to Locke, to Berkeley, to the standard of the knowledge and certainty of Newton, Hume declared that the human mind knows only its sensations and perceptions and spins those into associations, into ideas. Hume set in motion a train of thought that is now known as modern philosophical skepticism. We can assert nothing about reality, the thing in itself. When we talk, it is of our subjective experience. 

A crucial aspect of Hume’s epistemology must await another blogpost about his “nominalist” theory of concepts. Heir to a great philosophical sea change in the late Middle Ages, which sought to replace the ancient Greek theory of real “universals” with the theory that our concepts or abstractions are merely words or names (hence “nominalism”) for arbitrary groupings of particulars, Hume became the Enlightenment’s chief opponent of the theory of causality.

Our experience is only of particulars, concretes; we have seen billiard balls striking each other and moving, but never seen “causality.” Our experience therefore tells us that when we have observed a billiard ball that is struck by another, the first billiard ball rolls. That is all we know, not that one ball “caused” the other to roll—that is mere “speculation,” “metaphysics.” Without causality, of course, science becomes a quite different endeavor—a reporting of how some actions appear to follow from other actions, but with no attempt to explain how or why. That is one of the conclusions that alarmed Kant. 

As a brief aside, some critics of Humean epistemology respond: You are asserting that because we have a means of perceiving reality (seeing light waves with our eyes and interpreting their information with our brains), our perceptions are invalidated. Aren’t you arguing that the only valid perception would have to be achieved by no means because the means invalidate perception? An example of a powerful rebuttal of Hume’s viewpoint is by David Kelley, Ph.D., in The Evidence of the Senses.

Much contemporary philosophy rests on Humean skepticism and what later philosophers, especially Kant, did with it. But that is half or less of Hume’s legacy. He viewed himself primarily as a moralist and seemed to consider his work in that realm his most important contribution. The term “moral,” then, signified not “ethics” but any study of human nature. The outcome, Dialogues Concerning Natural Religion, a book he dared not publish during his lifetime, became the funeral dirge of the eighteenth century’s brimming optimism.