Keith Lehrer begins his intellectual biography of Thomas Reid by asking “How great a philosopher is Reid?” In answer, Lehrer relates the following story concerning his doctoral supervisor Roderick Chisholm:
When Chisholm was a department chairperson at Brown [University] he received a telephone call from a man saying that he was a busy man but had time to read one serious book in philosophy and wanted to do so. He said that he was not interested in entertainment but simply wanted to read a book with a greater amount of truth than any alternative. Chisholm, wishing to reflect on the matter, said the man should call back the next day, and he would give him his advice. The next day Chidholm recommended that the caller study Reid. It was a sound judgement.
The editors of this edition of Reid’s Lectures on Natural Theology not only agree but also see in these lectures a timely contribution to ongoing philosophical discussions.
Reid’s Lectures on Natural Theology as presented in this volume constitute a new edition of manuscript notes originally transcribed in the spring of 1780 by one of his students at the University of Glasgow. We will say more about the manuscript and its editorial history below, but first a few words about Reid and the contents of the Lectures.
Thomas Reid (1710–1796) was born in Scotland, in the village of Strachan (pronounced “Strawn”), not very far to the southwest of Aberdeen. He was born in the “manse,” the residence of the village’s Presbyterian minister, Reid’s father. He was educated at primary and secondary schools in Aberdeen, going on to take a degree in divinity at Marischal College, also located in that city, under the supervision of the philosopher and theologian George Turnbull (1698–1748). Upon coming of age in 1731, he was licensed to preach by the Church of Scotland and in due course he received his own ministry in the village of New Machar, north of Aberdeen.
Reid left the active ministry in 1752 to take up a position as lecturer at King’s College in Aberdeen, where he helped to form the “Wise Club,” a group of professors, ministers, and other prominent citizens, including the theologian George Campbell (1719–1796) and the philosopher James Beattie (1731–1803), both of whom became his lifelong friends. In 1764 Reid was called to occupy the prestigious chair in Moral Philosophy at the University of Glasgow, recently vacated by Adam Smith, a position he held until 1781, when he resigned it in order to concentrate on his writing. A frequent correspondent of the celebrated philosopher David Hume (1711–1776) and the eminent jurist and philosopher Henry Home, Lord Kames (1696–1782), Reid was one of the leading lights of the Scottish Enlightenment. Today, in the eyes of many, he is ranked second in importance among Scottish philosophers only to Hume.
The Lectures on Natural Theology have two natural audiences: (1) those interested mainly in Thomas Reid himself, as a thinker of abiding philosophical interest; and (2) those interested primarily in “natural theology,” that is, rational inquiry into the question of God’s existence and nature.
With respect to the first group, Reid’s work has undergone a stunning revival of interest since the 1970s, after more than a century and half of neglect—a revival which has only accelerated in the first two decades of the twenty-first century. Reid is stereotypically presented as the philosopher of “common sense,” and as someone principally concerned with epistemological issues. It is of course true that he held that our commonsense view of the world—the way things appear to us pretheoretically—ought always to be the ultimate touchstone of our philosophical theorizing. It is also true that he can be considered a forerunner of such influential twentieth-century thinkers as the British analytical philosopher G.E. Moore (1873–1958) and the American comparative psychologist and proponent of “direct realism,” James J. Gibson (1904–1979).
However, it is not true that the commonsense methodology, or even epistemological concerns more generally, exhaust the interest that Reid holds for contemporary philosophy. In fact, one of his greatest attractions for many thinkers today is the breadth of his interests, extending from logic, metaphysics, and “pneumatology” (philosophy of mind) to the philosophy of nature, ethics, and the philosophy of human society. Reid’s background in divinity supplied him with a deep familiarity with the classical (ancient and scholastic) philosophical tradition, which endowed him with an appreciation for the metaphysical aspect of the modern “way of ideas” that was not always apparent in his predecessors Locke and Hume.
It may be argued that the renaissance of interest in Reid goes hand in glove with the renewal of interest in Scholastic philosophy, and in metaphysics generally, that has occurred over the past couple of generations. For Reid possessed a virtually unique combination of philosophical virtues, at least among English-speaking thinkers: a penetrating analytical intelligence informed by a serene and candid philosophical personality grounded in a profound appreciation for the experience of all human beings in everyday life, as well as a wealth of knowledge of the history of philosophy.
For readers primarily interested in Reid as a remarkable and virtually sui generis representative of the Scottish and British philosophical traditions, the Lectures on Natural Theology will represent above all a valuable addition to the corpus of Reid’s writings. For nowhere else does he expound his views on God and religion in such full and often fascinating detail.
Regarding our second prospective group of readers—those interested primarily in the subject matter of the Lectures, namely natural theology—a few words on this vast subject will have to suffice. In the Lectures, Reid discusses several classical problems relating to the existence of God, of which three in particular are especially worthy of mention here: the cosmological argument; the teleological argument (the argument from design); and the problem of evil. Let us look at each of these briefly.
The cosmological argument appears in two main forms: (i) an argument from motion; and (ii) an argument from the finite temporal existence of the world. The first argument states that everything that moves must be set in motion by something else; everything in the world is or has been in motion; therefore, the world as a whole must have been set in motion by something outside the world.
The second argument—often referred to as the “kalām cosmological argument” due to its original development by early, Arabic-speaking theologians known as “mutakallimūn”—argues roughly as follows: The world is not eternal, but rather began to exist; everything that begins to exist is brought into existence by something else that already exists; therefore, the world as a whole was brought into existence by something eternal existing outside the world. Cosmological-type arguments had been discussed regularly down through the ages, right up until Reid’s time. On this topic, Reid is largely following expositions advanced by earlier English theologian-philosophers he admired, especially the Demonstration of the Being and Attributes of God (1705) by the eminent Anglican minister and friend of Isaac Newton, Samuel Clarke (1675–1729), and the Analogy of Religion, Natural and Revealed (1736) by the Anglican bishop and theologian, Joseph Butler (1692–1752).
The second of the three main topics of the Lectures mentioned above, and the one to which Reid pays the most lavish attention, is the teleological argument, better known nowadays as the “argument from design.” In its essentials, this argument simply states that complex composite objects (such as organisms) whose myriad parts are organized in such a way as to support the well-functioning of the whole (defined as its preservation-in-existence) do not appear to be explicable in terms of either natural law or chance (or their combination). Such natural composites would appear to require the same sort of explanation as manmade composites (like cars or computers)—namely, they seem to require that we posit a mind (or minds) that designed them intentionally to mutually support each other so as to achieve a specific purpose.
The Lectures offer numerous examples of such teleological phenomena, but perhaps the most intuitively compelling is the case of a meaningful text. Here Reid cites the Roman orator Cicero’s (106–43 BC) late work De Natura Deorum [On the Nature of the Gods] (45 BC), in which the author asks whether a “hog grubbing the earth” can form letters making a “complete sentence.” Reid claims it is intuitively obvious that such an object cannot be produced by either blind necessity or dumb luck. In our day this is usually cast as the proverbial roomful of monkeys banging away at typewriters to produce Hamlet’s soliloquy. By parity of reasoning, the argument goes, no well-functioning organism can be produced by either natural law or random chance (or their combination).
This argument was first mooted by Plato (c. 428–c. 348 BC) in the Timaeus. There, the Demiurge is invoked to explain the existence of order in nature, especially animals and human beings. After Cicero, the Church Fathers and the medieval Scholastics also returned to this argument with regularity. For instance, Gregory of Nazianzus (c. 329–c. 390 AD), in the second of his five Theological Orations (c. 380 AD), compares the world to a lute and its designer, God, to a lutemaker, as well as a luteplayer.
Closer to Reid’s own time, a similar discussion may be found in the Metaphysicae Synopsis,Oontologiam et Pneumatologiam Complectens [Synopsis of Metaphysics, Encompassing Ontology and Pneumatology] (1742), by the Ulster-born, University of Glasgow–based professor of moral philosophy, Francis Hutcheson (1694–1746). Following discussions of these and similar works, the bulk of the Lectures takes the form of the detailed description of innumerable marvels of the natural world, then recently revealed. The whole discussion is organized according to the mineral, plant, and animal “kingdoms,” with much attention to the structure of the human body.
One of the most interesting aspects of the Lectures for the modern reader is the way it reminds us just how much scientific information—in numerous fields of from astronomy, physics, and chemistry to natural history, including anatomy and physiology—was already available to the educated European public by the final decades of the eighteenth century. Moreover, the Lectures are also delightful for the way they encourage a sense of wonder in the young minds to which they are everywhere obviously directed.
Reid’s discussion of teleology in the Lectures remains philosophically significant not just for its contribution to the philosophy of religion but also for its take on the perennial problem of induction in epistemology. Reid delivered the Lectures in the year following Hume’s posthumous publication of The Dialogues Concerning Natural Religion (Hume died in 1776 and his Dialogues were published in 1779). And though a friend of Hume’s, Reid was not about to let Hume’s epistemological critique of the design argument stand. Hume had argued, in his Dialogues, that there was no way for induction to justify God’s hand in designing nature since we could have no experience of God’s activity in nature. As a hard-nosed empiricist, Hume therefore relegated the design argument to the dustbin.
Citing Hume by name, Reid countered in Lecture 79 that induction was irrelevant to the design argument, contending instead that we reliably infer design by identifying “the marks of intelligence and wisdom in effects.” Reid was thus urging that our minds are hard-wired to see design in marks or patterns that could only be ascribed to “a wise and intelligent cause.” In our own day, Alvin Plantinga has taken this view much further than Reid with the idea of proper function, in which our minds, when properly functioning in the right environment, perform various cognitive acts accurately, discerning the truth of the matter. Reid’s Lectures therefore provide a historically significant counterweight to Hume’s thoroughgoing empiricism, which to this day inspires epistemologists and philosophers of science.
The last of the three main topics of the Lectures mentioned above is the problem of evil. This is the puzzle regarding how the concept of an all-knowing, all-powerful, and perfectly benevolent deity may be reconciled with the evident existence of evil in the world. It, too, is a problem of great antiquity, originating in its classical form in the various writings of St. Augustine (354–430 AD), and avidly discussed, once again, by the mutakallimūn, as well as by numerous ancient, patristic, Scholastic, Reformation, and early-modern authors.
The problem of evil figures prominently in a number of works of Reid’s immediate predecessors, notably in De la Recherche de la Vérité [On the Search for Truth] (1675) by the French Oratorian priest, philosopher, and interlocutor of René Descartes, Nicolas Malebranche (1639–1715); in De Origine Mali [On the Origin of Evil] (1702; English translation, 1731) by the Anglican Archbishop of Dublin and theologian, William King (1650–1729); and even in the Essay on Man (1734), a didactic poem in heroic couplets by the renowned English poet, Alexander Pope (1688–1744).
Above all, the problem of evil is central to the Essais de Théodicée sur la Bonté de Dieu, la Liberté de l’Homme, et l’Origine du Mal [Essays in Theodicy on the Goodness of God, the Liberty of Man, and the Origin of Evil] (1710) (Theodicy, for short) by the great German mathematician, philosopher, historian, and all-around polymath, Gottfried Wilhelm Leibniz (1646–1716). Leibniz, who is frequently cited by Reid in the Lectures, argued, not just that the existence of God is compatible with evil, but that the created world we human beings inhabit is “the best of all possible worlds.” This did not mean that the world contains no evil; rather, it meant that any other world that God might have created in its stead would necessarily have been worse than this one, as it must have contained either more evil than this one, or less moral goodness, or both.
How is that?
Leibniz’s argument is complex, but it rests on two principal premises: (1) a world with free, morally responsible agents is better than a world without them; and (2) even God cannot violate the laws of logic. Now, it seems to follow from the first premise as a matter of logical necessity that if freedom exists in a world, then the abuse of freedom in the form of evil must be at least a possibility in that world, in which case it is more likely than not that it will become an actuality—that is, that evil will indeed occur.
If God grants freedom to humans, then God must have had no choice but to grant them the freedom to do evil, at least if there was to be moral goodness in the world at all. In other words, God allows evil to exist because it is a logical condition for the existence of moral goodness, and a world of morally good agents is a much better one that a world with nothing but mechanical puppets moving according to the same principles as the planets in their orbits or the balls on a billiard table. If that is so, then any deviation from the fundamental principles of the world as we know it that would reduce evil would reduce moral goodness as well, leaving the world as a whole worse off than it is. And if that is so, then we must indeed inhabit the best of all possible worlds—with the emphasis on the word “possible.”
This approach to “theodicy” (a word that Leibniz invented) was often referred to in the seventeenth century as the “rule of the best,” or as the philosophy of “optimism” (optimus being the Latin word for “best”). It is of some interest that Reid uses a different term. He calls Leibniz’s theodicy the “Beltistan theory” (from beltistos, the Greek word for “best”), a term that is very rare, but which does occur in a few other sources, notably in the Lectures on Divinity (c. 1768) by the Presbyterian minister and early Princeton College president, the Scottish-born John Witherspoon (1723–1794).
So much for the substance of the Lectures. Finally, though, we would be remiss if we did not mention yet another reason why the text we are publishing below ought to intrigue perceptive readers at the beginning of the third decade of the twenty-first century. That is, in recent years the teleological vision of the living world that Reid’s lectures so meticulously document, after suffering a century and a half of intellectual eclipse at the hands of Darwinian reductionism, has once again begun to win a scientific hearing for itself.
In a sense, of course, teleological thinking in biology never really went away. It has been there all along, if only in the form of a subterranean current nourishing biological understanding at a preconscious level for all these decades. What is the evidence for this claim? Biology lectures, biology textbooks—in a word—biologists themselves. It is impossible to listen to any biologist talk for more than a few minutes, or to open any biological textbook to practically any page, without encountering teleological or quasi-teleological (normative, evaluative, intentional, semantic) words and phrases in abundance.
The entire discipline of biology is steeped in teleological concepts and terminology. Take, for example, the following contrasting pairs: “functional/dysfunctional,” “healthy/diseased,” “beneficial/deleterious,” or simply “good-for/bad-for.” Biologists could not understand or communicate to each other the first thing about their subject if they did not think and speak in such terms. Not to mention that conceptual twilight zone which biologists entered some decades ago, where one hears constant reference being made to such utterly baffling notions (from a materialist perspective) as “information,” “meaning,” “codes,” “texts,” “messages,” “editing,” and “proofreading,” all spoken with an ontological poker face.
But, wait. Didn’t Darwin’s theory of natural selection put paid to all of that? Didn’t it teach us not to take such ways of speaking seriously, but to regard them as simply a convenient but ultimately expendable legacy effect of an older theistic worldview like Thomas Reid’s?
Not really. Or rather, that was the official view given out for public consumption. But the reality was that self-aware biologists always understood the disconnect between their official ideology and their everyday practice. They just adopted the practice of their physicist colleagues who, in quantum mechanics, were also saddled with an incomprehensible theory: “Shut up and calculate!” You didn’t need to explain the lingering presence of teleology everywhere in biology in order to do population biology; you just needed to do the math.
It should have been apparent all along—at least to those philosophers professionally engaged with the life sciences, if not to biologists themselves—that the official story put out for public consumption could not possibly be true. This, for two main reasons. First, the problem of combinatorial explosion. The more that was learned about the mind-boggling complexity of the cell, the less credible the idea that random variation was the source of evolutionary innovation. Whatever the Bayesian prior of standard neo-Darwinian selection theory may have been 70 years ago, since the advent of molecular biology it has plummeted spectacularly. We now know there is not enough time since the Big Bang for nature to have constructed so much as a single viable protein by means of a random walk, even if biased by selection, through the immensity of the phase space of all possible proteins, viable and non-viable. If evolution occurred, as it seems that it did, it certainly did not occur purely through a process of random variation and selection.
Over the past few decades, these things have come to be widely accepted within the mainstream biology community. This is not the place to recount in detail how this came to happen. But, certainly, due honor must be accorded to the thinkers of the “intelligent design (ID)” movement, who laid out the absurdity of the official Darwinian story with logical precision and in exquisite empirical detail. Many of those individuals who engaged in this collective exposé of the state of Emperor of Biology’s wardrobe paid the price for their remarkable stout-heartedness, being vilified and demonized, and having their academic careers derailed. Yet they have the satisfaction of knowing that their sacrifices were not in vain. For, thanks in no small part to the efforts of the ID movement, critics of the mainstream Darwinian view with no such affiliation have for some time now been springing up like mushrooms.
For anyone interested in the ID movement and the revolt against the official story it inspired, the Lectures will be of great interest. Indeed, Thomas Reid was nothing if not an intelligent-design advocate, even if the term “intelligent design” had yet to be coined. Reid’s advocacy of intelligent design centered on the patterns in nature (“the marks of intelligence and wisdom in effects”) that he saw as impossible for our minds to understand except as the product of another mind, which for him in this case was the mind of God. Evolution was not in the air in Reid’s day, so Reid was not an evolutionist. Yet nothing in his philosophy precludes that the design he saw in nature might nonetheless have gotten there through an evolutionary process. That said, Reid’s philosophy is as implacably opposed to Darwin’s anti-teleology as it is to Hume’s radical empiricism.
 Keith Lehrer, Thomas Reid (New York: Routledge, 1989), p. 1.
 A few landmarks include the Monist special issue dedicated to “The Philosophy of Thomas Reid” (vol. 61, no. 2) in April, 1978; Hackett’s 1983 publication of a low-cost anthology of extracts from Reid’s main works: An Inquiry into the Human Mind on the Principles of Common Sense (1764), Essays on the Intellectual Powers of Man (1785), and Essays on the Active Powers of Man (1788); the launching of the journal Reid Studies by the University of Aberdeen in 1986; and the publication of Keith Lehrer’s Thomas Reid in Routledge’s “Arguments of the Philosophers” series in 1989 (cited in the opening of this introduction). More recently, the Thomas Reid volume in the “Cambridge Companions to Philosophy” series (edited by Terence Cuneo and René van Woudenberg, 2004) and, above all, the publication of the uniform “Edinburgh Edition of Thomas Reid” in ten volumes (General Editor: Knud Haakonssen, 1995–2020) testify to the present flourishing condition of Reid studies.
 The term kalām means rational discourse about religion; mutakallimūn (s. mutakallim) are those who practice kalām. It is interesting that the term kalām is derived from the Arabic root, k-l-m, meaning “to speak”; thus, etymologically, the word means something like “debate” or “disputation.” Compare the Greek verb λέγω [legō], also meaning “to speak,” and the nominal forms derived from it, such as λόγοϛ [logos] (“word,” “speech,” “reason”) and διαλεκτική [dialektikē] (“debate”). This resemblance is no accident, as the historical roots of kalām most likely lie in the forms of “dialectic” practiced within seventh- and eighth-century AD, Syriac-speaking, Christian communities in the Near East, who had taken them over from their Greek-speaking co-religionists. See Alexander Treiger, “Origins of Kalām,” in Sabine Schmidtke, ed., The Oxford Handbook of Islamic Theology (Oxford University Press, 2016); pp. 27–43.
 See William Lane Craig, The Kalām Cosmological Argument (Macmillan Press, 1979; reprinted by Wipf and Stock Publishers, 2000).
 See William Lane Craig, The Cosmological Argument from Plato to Leibniz (Harper & Row Publishers, 1980; reprinted by Wipf and Stock, 2001).
 Gregory of Nazianzus, “Select Orations,” tr. by Charles G. Browne and James E. Swallow, in A Select Library of the Nicene and Post-Nicene Fathers of the Christian Church, Second Series, ed. by Philip Schaff and Henry Wace (William B. Eerdmans Publishing Co., 1952) [originally published in 1896], Vol. VII, pp. 185–434. The lute/lutemaker metaphor occurs in Oration 28, “The Second Theological Oration,” pp. 288–301, in section VI on p. 290.
 Alvin Plantinga, Warrant and Proper Function (Oxford: Oxford University Press, 1993).
 Eric Linn Ormsby, Theodicy in Islamic Thought (Princeton University Press, 1984).
 John Hick, Evil and the God of Love (Palgrave Macmillan, 2010 [1st ed., 1966]).
 The term occurs at the start of Lecture 84 of Reid’s Lectures on Natural Theology (see especially note 97 of this present edition). The Witherspoon example, which appears in the slightly variant form “Beltistian,” may be found in The Works of John Witherspoon, D.D. (Edinburgh, 1815), in volume VIII on p. 108. We ought perhaps to make clear that while Witherspoon mentions the “Beltistian scheme” in passing, he does not in fact uphold it. In general, he is far less sanguine about rational, or “natural,” religion than is either Hutcheson or Reid.
 Another problem is that organisms are not passive mechanical systems, but are active and adaptable. As a result, whatever the processes of genetic mutation may be, the resulting gene products are actively entrained by the organism into a modified dynamical equilibrium regime, if at all possible. This means that the theory of natural selection presupposes teleology, and so cannot explain it.
 Some of the main landmarks in the ID movement are the following: Phillip E. Johnson, Darwin on Trial (Regnery Publishing Co., 1991); Michael J. Behe, Darwin’s Black Box (Free Press, 1996); William A. Dembski, The Design Inference (Cambridge University Press, 1998); Stephen C. Meyer, Darwin’s Doubt (HarperOne, 2014).
 Some of the key texts in this area are the following: Franklin M. Harold, The Way of the Cell (Oxford University Press, 2001); Mary Jane West-Eberhard, Developmental Plasticity and Evolution (Oxford University Press, 2003); Mae-Wan Ho, The Rainbow and the Worm, 3rd ed. (World Scientific, 2008); Stuart A. Kauffman, A World Beyond Physics (Oxford University Press, 2019); Marc W. Kirschner and John C. Gerhart, The Plausibility of Life (Yale University Press, 2005); Robert B. Laughlin, A Different Universe (Basic Books, 2005); Denis Noble, Dance to the Tune of Life (Cambridge University Press, 2017); Gerald H. Pollack, Cells, Gels, and the Engines of Life (Ebner and Sons, 2001); James A. Shapiro, Evolution: A View from the 21st Century (FT Press, 2011); J. Scott Turner, Purpose and Desire (HarperOne, 2017). See, also, the “Third Way of Evolution” website: https://www.thethirdwayofevolution.com.