Common Sense Realism

1. Scope and evidence

The core biographical and doctrinal claims on this card are Established and rest on primary texts (Reid's three books and his correspondence) and authoritative reference works (Stanford Encyclopedia of Philosophy, Internet Encyclopedia of Philosophy, Routledge Encyclopedia of Philosophy). The characterisation of Reid's argument against the "way of ideas" as a reductio is the standard scholarly reading (Lehrer, Wolterstorff) and is Established, though the details of Reid's positive epistemology remain a live scholarly discussion. The single most important point requiring precision — flagged here per the site's "accuracy over patriotism" standard — is that Reid's "common sense" is a technical term for a body of first principles, not the colloquial sense of practical wisdom or majority opinion; treating the two as equivalent is a persistent and unfair misreading. The Stanford Encyclopedia of Philosophy notes that stressing the universality of beliefs "has opened Reid up to tiresome criticism that began in his lifetime and continues to the present of the following sort: Reid's appeals to common sense are little more than affirmations of majority opinion or appeals to the masses, but these are fallacious, so his inferences from such principles are defeated" — a criticism the SEP itself says rests on a misunderstanding. The claim that Reid and Hume were mutually respectful correspondents is Established from their surviving letters. Some downstream influence claims (e.g. Reid's precise weight in American political rhetoric, or whether Moore consciously drew on Reid) are Shared/Traditional and are flagged where they arise.

2. Reid's life and the Aberdeen Philosophical Society

Thomas Reid was born on 26 April 1710 in the manse of Strachan, a small parish in Kincardineshire on Deeside, the son of a Church of Scotland minister; through his mother he was connected to the mathematical Gregory family. He entered Marischal College, Aberdeen, and graduated MA in 1726, afterwards serving as college librarian. In 1737 he was presented to the living of New Machar, north of Aberdeen, where he served as Presbyterian minister until 1751. It was during these pastoral years that he read Hume's Treatise of Human Nature (1739), the book he would later credit with rousing him from his philosophical complacency.

In 1751 Reid was elected Regent at King's College, Aberdeen — a post in which he taught the full curriculum across mathematics, the sciences and philosophy. In 1758 he was a leading founder of the Aberdeen Philosophical Society, affectionately nicknamed the "Wise Club," a group of professors and ministers who met twice a month. This society was the intellectual crucible of Reid's mature philosophy: its members — who included the rhetorician George Campbell, the aesthetician Alexander Gerard, the physician John Gregory and, from 1761, the poet-philosopher James Beattie — subjected Hume's writings to sustained discussion, and the papers Reid read to the club grew directly into the Inquiry. In 1764, the year the Inquiry appeared, Reid was appointed to the Chair of Moral Philosophy at Glasgow, succeeding Adam Smith (whose own concepts are treated elsewhere in this series). He held the chair until his death in 1796, resigning active teaching around 1780 to concentrate on the two great Essays.

3. The key works

Reid's philosophy is contained in three books. An Inquiry into the Human Mind on the Principles of Common Sense (1764) was written explicitly as a considered response to Hume; methodologically pioneering in its use of observational data, it works through each of the five senses in turn to show how we gain knowledge of the world. Essays on the Intellectual Powers of Man (1785) extends the system to memory, conception, judgment, reasoning and taste, and contains (in Essay VI) his fullest treatment of "first principles." Essays on the Active Powers of Man (1788) addresses ethics, agency and his libertarian, agent-causal theory of free will. All three, with his correspondence and manuscripts, are now published in the scholarly Edinburgh Edition of Thomas Reid.

Reid was candid that he had not always been a critic of the received view. In the Dedication to the Inquiry he records his intellectual reversal in a famous passage: "I acknowledge, my Lord, that I never thought of calling in question the principles commonly received with regard to the human understanding, until the Treatise of Human Nature was published in the year 1739. The ingenious author of that treatise, upon the principles of Locke — who was no sceptic — hath built a system of scepticism, which leaves no ground to believe any one thing rather than the contrary. His reasoning appeared to me to be just; there was therefore a necessity to call in question the principles upon which it was founded, or to admit the conclusion." He had earlier been persuaded by Berkeley's immaterialism; Hume's Treatise convinced him that the whole shared framework must be wrong.

4. The rejection of the "Way of Ideas"

Reid's central and most original move is his attack on what he called the "theory of ideas" or the "way of ideas" — the representational model of the mind he found running through Descartes, Malebranche, Locke, Berkeley and Hume. On this model, the mind never directly perceives external objects; it perceives only its own internal ideas, impressions or images, which stand between us and the world like a screen or "veil of perception." Reid argued that once this premise is granted, scepticism becomes unavoidable: if all we are ever directly aware of are ideas in our own minds, there is no way to establish that anything corresponds to them — hence Berkeley's idealism and Hume's scepticism about the external world, causation, and personal identity.

Crucially, Reid agreed with Hume that the theory of ideas, followed consistently, leads to Humean scepticism. He simply turned this into a reductio ad absurdum: because the sceptical conclusion is unacceptable — indeed, one that no one can actually live by — the shared premise must be false. As one scholarly summary puts it, "Reid agreed with Hume that, if the immediate objects of perception are ideas in the mind, no certain knowledge of an external world is possible. He turned this conditional into a reductio: the conclusion is unacceptable, so the premise must be wrong. The way of ideas is therefore false." Reid additionally objected that "ideas" as posited entities have no observational evidence in their favour and violate Newton's first rule of philosophising (admit no more causes than are true and sufficient). In their place he defended direct (or natural) realism: in perception the mind is put into immediate cognitive contact with external objects themselves, not with mental proxies. He carefully distinguished sensation (the felt inner state) from perception (the cognitive grasp of the object), locating direct contact with the world at the level of perception. He applied the same reductio strategy against Hume's bundle theory of the self and his analysis of causation.

5. The positive doctrine: first principles of common sense

Reid's positive doctrine is that all reasoning must ultimately rest on a set of first principles — propositions he variously calls "first principles, principles of common sense, common notions, or self-evident truths" (Essays on the Intellectual Powers 6.4). These cannot themselves be proved, because any proof would already have to assume them; but they are not therefore arbitrary. They are, in Reid's view, universal natural convictions "unconditionally given to all men by the Author of Nature," built into the human constitution, believed as soon as they are understood, and — decisively — impossible for even the sceptic to abandon in practice. Reid's examples include that the objects we distinctly perceive really exist and are what we perceive them to be; that the thoughts I am conscious of belong to a self that persists through time; that memory is generally trustworthy; that other minds (other thinking beings) exist; that natural faculties by which we distinguish truth from error are not fallacious; and that whatever begins to exist has a cause.

The SEP stresses a point often missed: Reid's appeal to universality is not a crude appeal to majority opinion but functions as "an empirically justified generalization about species-typical features of human cognition." Reid does not think first principles merely describe what people happen to believe; he thinks they provide evidence for particular beliefs (Principle 5, that what we distinctly perceive really exists, licenses the self-evident belief that I perceive, say, a table before me). His method is thus a fallibilist foundationalism: knowledge rests on self-evident starting points, but these are defended less by positive proof than by showing that the sceptic's alternatives are no better supported — a burden-of-proof strategy.

Here is the subtle and important relationship to Hume. Hume himself had conceded (in his "sceptical solution," treated on Card #6) that custom and natural belief carry us through life even though reason cannot justify them. Reid takes essentially the same naturalistic observation — that we cannot help believing in the external world, causes, and the self — but draws the opposite philosophical conclusion. Where Hume treats these irresistible beliefs as merely psychologically inevitable habit that reason cannot vindicate, Reid argues they are rational precisely because they are the deliverances of our natural constitution, and are therefore properly held as basic. In this sense Reid can fairly be described as taking Hume's own naturalism and insisting that it be recognised as genuine rational grounding rather than a bare psychological fact — which is exactly why his response is philosophically serious rather than a mere refusal to play the sceptic's game.

6. The critical distinction: technical vs colloquial "common sense"

This is the point the card most needs to get right. When Reid says "common sense," he is not appealing to the folksy, everyday notion of practical wisdom, native shrewdness, or what "everybody knows." In his usage the phrase is a technical term for the specific body of first principles described above — the universal, non-provable, self-evident convictions that are constitutive of rational human cognition. It follows an established philosophical lineage: the Latin sensus communis, reaching back through Aristotle and the Stoic Cicero (from whom Reid took the term) and revived by Shaftesbury's Sensus Communis (1710).

The reason this matters is that the colloquial reading has caused Reid to be unfairly dismissed. Because he sometimes wrote in defence of "the opinions of the vulgar," and because his contemporary James Beattie popularised a cruder, more rhetorical version of "common sense" in his best-selling Essay on the Nature and Immutability of Truth (1770), Reid acquired a reputation as a philosopher who simply banged the table for ordinary opinion against clever sceptics. The Stanford Encyclopedia of Philosophy is explicit that this "tiresome criticism... began in his lifetime and continues to the present," and that it rests on a misunderstanding: Reid's first principles are psychological generalisations about universal belief-formation, offered as evidence, not fallacious appeals to the masses. Serious Reid scholarship (Lehrer, Wolterstorff, the Cambridge Companion to Reid) treats his position as a rigorous, technically defined epistemology of the foundations of knowledge — closer to what a modern epistemologist means by "properly basic beliefs" than to anything in a self-help sense of "common sense."

7. Reid's relationship with Hume, examined fairly

The popular image of Reid as Hume's implacable refuter is misleading. The two Scots were contemporaries who conducted an infrequent but courteous and mutually respectful correspondence. Reid admired Hume's philosophical acuity and read him more attentively than almost anyone else of the period. Before publishing the Inquiry, Reid deliberately sent the manuscript to Hume for comment, routed through their mutual friend the Edinburgh minister and rhetorician Hugh Blair. Hume, having read portions of it, replied on 25 February 1763 in a generous and characteristically measured letter: "By Dr. Blair's means I have been favoured with the perusal of your performance, which I have read with great pleasure and attention. It is certainly very rare that a piece so deeply philosophical is wrote with so much spirit, and affords so much entertainment to the reader, though I must still regret the disadvantages under which I read it, as I never had the whole performance at once before me." In a separate covering note to Blair, Hume remarked that the work was written "in a lively entertaining manner" but complained of "some Defect in Method" and that Reid's doctrine seemed to imply innate ideas.

Reid's own reply, written in March 1763, is strikingly generous to his opponent: he thanks Hume warmly and declares, "I shall always avow myself your disciple in metaphysics. I have learned more from your writings in this kind than from all others put together." He describes the Aberdeen circle affectionately trying Hume "at the bar, accused and defended with great zeal, but without bitterness." The accurate picture, then, is of two philosophers in fundamental disagreement conducting themselves with real intellectual friendship — not a hero-and-villain story. Reid thought Hume's conclusions disastrous, but he respected Hume's reasoning enough to treat it as the crucial test case that exposed the rot in the whole "ideal system."

8. The Scottish School of Common Sense and its spread

Reid founded what became a recognised philosophical movement, the Scottish School of Common Sense (also "Scottish Common Sense Realism"), whose other early figures included James Beattie, James Oswald, George Campbell and later William Hamilton. Its most important immediate successor was Dugald Stewart (1753–1828), who had attended Reid's Glasgow lectures in 1771, held the Edinburgh Chair of Moral Philosophy from 1785, and through brilliant teaching and widely reprinted books (notably the Elements of the Philosophy of the Human Mind) became the school's great populariser. Stewart adopted a somewhat more moderate realism but transmitted Reid's core method — starting from the "fundamental laws of belief" of ordinary experience — to an international audience.

The movement became a genuine intellectual export. In France, Reid was introduced by Pierre Paul Royer-Collard and became, through his pupil Victor Cousin and through Théodore Jouffroy (who translated Reid's and Stewart's works), a dominant force in nineteenth-century French academic philosophy; according to Encyclopædia Britannica, "from 1816 to 1870 the Scottish doctrine was adopted as the official philosophy of France." In America, the school's influence was even more institutionally decisive. John Witherspoon, the Scottish minister who became president of the College of New Jersey (Princeton) in 1768 and the only clergyman to sign the Declaration of Independence, brought Scottish common-sense moral philosophy to Princeton (Reid's later Essays and Stewart's Elements, published from 1785 and 1792, were taught after him rather than by him); Common Sense realism then became, in the phrase historians use, the "orthodox philosophy" of American colleges for roughly half a century, taught from named chairs — Samuel Stanhope Smith at Princeton, Noah Porter at Yale and Francis Bowen at Harvard — and later revived at Princeton by James McCosh. Its imprint on American moral education, and arguably on the "self-evident truths" idiom of the founding era, was substantial (the latter a Shared/Traditional claim rather than a settled one).

9. How common sense reached American colleges

The literary historian Andrew Hook, in Scotland and America: A Study of Cultural Relations, 1750–1835 (1975), gives the most detailed account of how the common sense school entered American teaching. Some Scottish philosophy was read in America before John Witherspoon arrived in 1768: Jonathan Edwards had read Kames and Hume by 1755, one of Hutcheson's works was a textbook at the Philadelphia Academy in 1756, and a gift of books to Rhode Island College (later Brown) in 1771 included "Reid on the Mind", the Inquiry. Witherspoon then gave the ideas an institutional home. Samuel Miller's Brief Retrospect of the Eighteenth Century (1803) called him the first in America to teach the substance of the philosophy of mind that Reid developed, and a Princeton student of the 1790s, Frederick Beasley, recalled that Reid and the Scottish metaphysicians held "undisputed sway" there. (Established.)

After the Revolution American printers, freed from British copyright, reprinted the Scots. Reid's Essays on the Intellectual and Active Powers appeared at Philadelphia in 1792 and 1818, and his Works at Charlestown, Massachusetts, in 1813–15 and 1818 and at New York in 1822. The first volume of Stewart's Elements was printed at Philadelphia in 1793, a year after its British publication, and a North American Review article of 1824 counted eight American editions, some 7,500 copies. By about 1800 the moral philosophy course at William and Mary used Duncan, Reid and Stewart; Harvard, Yale and Brown set Stewart by the 1810s and 1820s; and examination papers at the new University of Virginia around 1828 expected students to discuss Brown, Blair, Stewart and Adam Smith. (Established.)

The historian Herbert Schneider (1946) dated the Scottish "invasion" of American philosophy teaching to about 1820. Hook argues that by 1820 the change was already complete, having begun just after the Revolution. He offers two reasons for its success: as a reply to Hume's scepticism the school suited the religiously orthodox men who ran most colleges, and its account of self-evident principles fitted the natural-law language of American politics, as in the work of the Scottish-born signer James Wilson. These are Hook's interpretations (Shared). Later historians, among them Douglas Sloan (1971) and Henry May (1976), accept the scale of the Scottish influence while setting it beside English and continental sources; the stronger claim of Garry Wills (1978) that Scottish philosophy shaped Jefferson's Declaration was sharply challenged by Ronald Hamowy and remains disputed.

10. Reid's modern revival and contemporary relevance

Through the later nineteenth and much of the twentieth century Reid was eclipsed — his reputation collapsing under the prestige of Kant and Hegel, and Hume coming to be read as the towering figure of the British Enlightenment. (Kant himself had set the dismissive tone in the Prolegomena, complaining that Reid appealed "to the common sense of mankind" as a "convenient means of putting on a bold face without any proper insight into the question," an appeal that let "the emptiest babbler" attack "a thinker of Hume's calibre" — a verdict aimed largely at the cruder, Beattie-flavoured version of the school.) Since the 1970s and 1980s, however, Reid has undergone what scholars describe as a stunning revival, accelerating into the twenty-first century. Key figures include Keith Lehrer, whose Thomas Reid (1989) gave a full overview of his philosophy, and Nicholas Wolterstorff, whose Thomas Reid and the Story of Epistemology (2001) produced the first systematic account of his epistemology and argued for its contemporary relevance. Reid is now firmly re-established in the canon; the Cambridge Companion to Reid (2004) and the ongoing Edinburgh Edition mark his rehabilitation.

Two contemporary connections stand out. First, G.E. Moore's celebrated "A Defence of Common Sense" (1925) defends a list of "truisms" — that the earth existed before my birth, that other people with minds exist, and so on — against scepticism and idealism, using a strategy strikingly parallel to Reid's; scholarship treats Reid as an antecedent (some argue Moore likely encountered Reid's work during his years in Edinburgh after 1904, though the influence is best described as a strong parallel rather than a fully documented debt). Second, and more directly, Reid is an acknowledged source for reformed epistemology, the school associated with Alvin Plantinga, William Alston and Wolterstorff, which holds that certain beliefs (including belief in God) can be "properly basic" — rationally held without inferential evidence, much as Reid held perceptual and memory beliefs to be. Plantinga and Wolterstorff explicitly draw on Reid's account of non-inferential, properly basic belief; contemporary theories of perception (direct realism) and of testimony also cite Reid as a forerunner.