Download PDF PDF Page Citation Cite Share Link Share

Last Updated on May 6, 2015, by eNotes Editorial. Word Count: 2370

Illustration of PDF document

Download Thomas Reid Study Guide

Subscribe Now

Article abstract: Famous for his criticism of “the way of ideas” and its attendant skepticism, Reid defended “common sense” and human freedom.

Early Life

Thomas Reid was born into distinguished families. His father and ancestors for several generations had been clergymen in the Church of Scotland. On his mother’s side, the Gregory family included the inventor of the reflecting telescope, two mathematics professors in Scotland, and a professor of astronomy at Oxford University. Reid’s own career alternated between the vocations of pastor and professor.

Reid was home schooled until he entered Marischal College, Aberdeen, at the age of twelve. By the time he graduated four years later, he had embraced George Berkeley’s immaterialist philosophy. Reid trained for five years for the Christian ministry, then took the position of librarian at Marischal College between 1733 and 1737, which allowed him to continue his study of John Locke’s philosophy and Isaac Newton’s physics.

In 1737, Reid became the pastor at New Machar, a rural parish just outside Aberdeen. Because the congregation had little input into his appointment, Reid’s ministry had a troublesome start. He married his sixteen-year-old cousin, Elizabeth, four years later. She helped smooth the situation in New Machar, and the congregation grew to love their pastor and his wife during their ten years of service together. The Reids had nine children, but eight died in infancy and young adulthood. Only a daughter, Martha Carmichael, survived.

Reid was forty-one years old when he accepted the invitation in 1751 to become a regent professor at King’s College, Aberdeen. A regent professor taught a group of college students all their courses for three years, then presented them for graduation. Reid taught the sciences and mathematics for two years. Only in the third year would he teach ethics and philosophy, the subjects on which he published. In 1758, he helped organize the Aberdeen Philosophical Society, affectionately called the Wise Club by the small group of professors and ministers who gathered twice a month at a local pub. Reid’s first book, An Inquiry into the Human Mind on the Principles of Common Sense, grew from his presentations and discussions in that group.

Life’s Work

Reid was fascinated by the great Scottish philosopher David Hume’s A Treatise of Human Nature (1739-1740). He pored over it as a young pastor and later reviewed the book intensely with his friends in the Aberdeen Philosophical Society.

Hume claimed in A Treatise of Human Nature that people have only two sorts of knowledge and that both are grounded in perceptions of ideas. One either notices necessary relations between ideas (as when noting that “dolphins are mammals”) or knows that things contingently exist because one perceives ideas of them (as when seeing that “there swims Flipper the dolphin”). The young Reid accepted this view. He was genuinely shocked at the skeptical conclusions that Hume carefully deduced from these apparently simple claims. Hume argued that if people perceive only ideas, then they cannot know any reality that is different and beyond those ideas. Ideas are fleeting and entirely separate from one another, not at all like the enduring objects that people believe to exist and to interact one with another. Consequently, from the experience of ideas, people can give no reason to believe that bodies and minds exist, that God exists, or that anything (or anyone) actually causes any event to occur.

Reid accepted the challenge of explaining how people can know such realities through experience. In An Inquiry into the Human Mind on the Principles of Common Sense, he questioned Hume’s key assumption (which Reid variously termed “the ideal theory” or “the way of ideas”) that people perceive ideas. Reid thought this assumption was the root of skepticism in the work of all modern philosophers (whom he judged to be René Descartes, John Locke, and their followers down to his contemporary, David Hume). People mistakenly accept the ideal theory, Reid said, because they confuse sensation and perception. They mistakenly believe that they perceive their sensations. Reid, therefore, kept these processes separate. Sensations are fleeting and separate episodes in consciousness; they just happen to people. Perceptions, on the other hand, involve acts that people do; usually, perceptions are about things that exist continuously outside consciousness. For example, when people type by touch, their sensations are slight momentary pains. They perceive, however, an enduring three-dimensional keyboard at their fingertips. Reid’s point is that people do not perceive the sensations (unless, as when thinking about this example, they concentrate on those brief pains), but they perceive something outside consciousness, the keyboard. They conceive the keyboard and then have perceptual beliefs about the keyboard existing, being on the desk, having a light key touch, and so on. In other words, the object of perception is not ideas, but an enduring, causally engaged reality outside the perceiver.

Hume had declared that conceptions are copied from prior sensations (for example, one can think of cerulean blue because one has had sensations of the blue sky). Reid’s new position was that conceptions usually are nothing like sensations. The conception of an enduring three-dimensional keyboard is nothing like a momentary pain, but upon feeling the latter, the mind thinks of the former. If (as Reid said) there is no similarity between sensations and objects of perception, why, when people have sensations, do they think of a particular object of perception? That is just how the human mind works, Reid argued. Many conceptions and perceptual beliefs are basic and unexplainable. It is a law of human nature that certain sensations are the occasion of certain conceptions and perceptual beliefs, just as it is a law of nature that physical objects attract one another gravitationally. As observers, people can discover these laws, but they cannot explain why the laws work as they do.

Reid’s reputation as a philosopher spread. He accepted the prestigious Chair of Moral Philosophy at the University of Glasgow in 1764 so that he could concentrate on his study of the human mind and agency. He nevertheless lectured busily and did not publish his research for sixteen years. Aware of his diminishing strength in old age, Reid entered semiretirement in 1780. A colleague taught Reid’s assigned classes, giving Reid the opportunity to revise his lectures for two final publications: Essays on the Intellectual Powers of Man and Essays on the Active Powers of Man.

Reid is most famous for his doctrine of common sense. It has been widely misunderstood as an easily refuted view—somewhere in the intellectual neighborhood of “anything that most people believe must be true,” or “people should keep their unexamined prejudices regardless of overwhelming counterevidence.” Reid, however, meant nothing of the sort. He carefully defined his terms in Essays on the Intellectual Powers of Man. By “common,” he meant what people must be like if one is to talk and interact with them; “sense” meant judgment—in both its meanings, as a belief and as a power to form beliefs. By “common sense,” Reid meant the beliefs people must have so that others can live with them and, consequently, the faculties that they need to form such beliefs.

Reid argued that beliefs arise from a network of evidence-giving faculties such as self-consciousness, sense perception, memory, trust of other people’s testimony, something like “seeing” basic logical patterns, reasoning (following arguments), and noticing the presence of causal agents. When these faculties function properly, they provide true basic beliefs such as these: A person has existed for (at least) as long as he or she remembers existing; other people have experiences; physical objects that people perceive really do exist; 2 + 2 = 4; and if “A” and “A then B,” then “B.” Other philosophers wanted proofs that physical objects, other minds, and causes exist. Reid responded that there could be no proofs, because people know nowhere else to start. These are basic beliefs from which other beliefs are proved. As a thought experiment, consider the following: A person asks someone to prove that other people have minds. To whom is this argument made? From what shared beliefs can the argument begin?

Faculties of common sense sometimes malfunction—as when a person is poked in the eye, the memory is clouded by drugs, or reasoning is distorted by a powerful desire to dominate a debate. Can people be absolutely certain that their faculties are functioning properly at any given moment? That is, can people know that they know? Reid answered negatively—people’s knowing is fallible. That is no reason, however, to distrust people’s faculties, because people have no other way to know when they are malfunctioning. People spot a faulty memory by using their faculties: by other remembering, by trusting another person’s testimony, or by reasoning from present evidence.

Reid criticized especially Descartes’s project in Meditationes de prima philosophia (1641; Meditations on First Philosophy, 1680). Descartes had begun by doubting the faculties of sense experience. He later argued that God exists and guarantees that human senses are trustworthy after all (when used as carefully as God intended). Reid objected that if one or several faculties are totally doubted for any reason, then all knowing faculties must be doubted (for that same reason)—including people’s ability to reason about God’s existence. Descartes had dug a pit of skepticism out of which no one could climb.

This objection to Descartes’s method is crucial for understanding Reid’s own position concerning God and knowledge. One cannot prove God’s existence before trusting one’s knowing faculties. Reid did think, however, that theists have a reason ultimately to trust people’s knowing faculties, namely, that these were designed by a loving Creator for the task of obtaining true beliefs. Nontheists do not have this reason, and they well may have other beliefs (for example, that human faculties were an unintended result of physical processes) that undermine trust in these faculties’ truth-getting function.

Reid gave a powerful defense of human free will in Essays on the Active Powers of Man. When people act freely, they determine what they choose, and choice governs what they do. (Not all actions are free, of course; something might determine choice, or people might not act as they choose.) People are morally responsible for these free actions because no other persons or events totally determine those actions.

People are creatures embedded in the causal patterns of the universe, leading to the question of whether freedom of choice is possible. One might question whether every act of choosing has some cause, which might be some prior event beyond one’s choosing or control. Reid agreed that free choices have a cause, but that cause is the human agent, not some prior event. This is compatible with radical human freedom.

In later life, Reid became deaf, but he still enjoyed his favorite activities: one-on-one conversations, walking several miles each day, gardening, and working out mathematical proofs as a hobby. Reid’s wife, Elizabeth, died in 1792, and Reid died four years later after a brief violent illness.


Reid imaginatively appraised seventeenth and eighteenth century philosophy. From Irish philosopher Berkeley, he rescued the insight that people have a notion of mind even though they do not experience minds; thus, they must be able to form conceptions of something other than of sensations. The innateness of these concept-forming abilities is a fertile reworking of Descartes’s theory of innate ideas. To explain the relationship between sensation and perception, Reid borrowed Berkeley’s theory signs. Reid said sensations are signs that signify conceptions and beliefs about objects of perception. Locke’s realism and trust in experience also found their echo in Reid’s optimistic account of knowledge.

Philosophers in the United States early in the nineteenth century were looking for an adequate response to the skepticism and atheism implicit in modern philosophy. Many of them believed Reid supplied that answer. Charles Sanders Peirce, the founder of pragmatism, continued to develop Reid’s theory of signs. By the twentieth century, however, skepticism and atheism were preferred views among intellectuals. Reid’s reputation suffered as a thinker who had struggled futilely against the drift of modern thought. His theory of knowledge went out of fashion as, once again, many philosophers claimed to find certainty in the evidence of immediate consciousness or sense experience.

By the late twentieth century, the intellectual drift was going another way. Many believed that modern thought was a grand mistake, and they heralded the coming of a “postmodern” age. Moderns, they said, longed for certainty in knowledge, mistakenly believed they had found it, and then used their opinions to dominate and rule out all others. The postmodern thinkers instead endorsed human fallibility and preached tolerance. Reid had anticipated these critiques of modern philosophy, yet where postmodern thought itself led toward moral skepticism and a distrust of theism, Reid would not have followed. It is not surprising that a number of distinguished American philosophers, including Roderick Chisholm, Keith Lehrer, Nicholas Wolterstorff, William P. Alston, and Alvin Plantinga, became proponents of Reid’s alternative way of avoiding the skepticism and hubris of modern philosophy.

Additional Reading

Beanblossom, Ronald E., and Keith Lehrer, eds. Thomas Reid’s Inquiry and Essays. Indianapolis, Ind.: Hackett, 1983. This inexpensive paperback contains generous selections from Reid’s published writings.

Dalgarno, Melvin, and Eric Matthews, eds. The Philosophy of Thomas Reid. Boston: Kluwer Academic, 1989. The essays in this anthology are representative of the current interest in Reid’s philosophy.

Diamond, Peter J. Common Sense and Improvement: Thomas Reid as Social Theorist. New York: Peter Lang, 1998. A keen study of Reid’s thoughts on social theory.

Fraser, Alexander C. Thomas Reid. Bristol: Thoemmes Press, 1993. An informative and thorough biography of Thomas Reid.

Gallie, Roger D. Thomas Reid: Ethics, Aesthetics, and the Anatomy of the Self. Boston: Klumer Academic, 1998. An important evaluation of Reid’s moral philosophy and his aesthetics aimed at the advanced undergraduate to graduate level.

Lehrer, Keith. Thomas Reid. New York: Routledge, 1989. An excellent introduction to Reid’s thought.

Rowe, William L. Thomas Reid on Freedom and Morality. Ithaca, N.Y.: Cornell University Press, 1991. In this fine study of Reid’s Essays on the Active Powers of Man, Rowe develops a defense of Reid’s theory of human freedom.