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INTRODUCTION - George Turnbull, The Principles of Moral and Christian Philosophy. Vol. 1: The Principles of Moral Philosophy 
The Principles of Moral and Christian Philosophy. Vol. 1: The Principles of Moral Philosophy, ed. and with an Introduction by Alexander Broadie (Indianapolis: Liberty Fund, 2005).
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natural law and enlightenment classics
George Turnbull was born on 11 July 1698, probably in the Scottish town of Alloa in Clackmannanshire where his father was the Church of Scotland parish minister. Turnbull entered Edinburgh University in 1711 and continued his studies there till about 1716, though he did not proceed to graduation until 1721, the year in which he became regent at Marischal College, Aberdeen. The regent’s principal task was to instruct a cohort of students in a three-year cycle of studies that included the mathematical and natural sciences, moral philosophy, and natural theology. On becoming regent he inherited a cohort that was already partly through its cycle and that completed it, under Turnbull’s instruction, in 1723. His next cohort, which he taught from 1723 until 1726, included Thomas Reid. During his period as regent, Turnbull became the first of a long line of Scottish moralists to speak explicitly about the introduction of the experimental method of reasoning into moral subjects.
Turnbull’s teaching had been interrupted by a visit to continental Europe in 1725, when, without the permission of his university, he traveled for a few months in the role of tutor to the Udney family. He was recalled to Marischal and was back at his post by the start of the following year, though in a sense under protest, since he had made it clear in correspondence that, as he put it: “I wish heartily I may be so lucky as to have no more to do with that place.”1 This fragment of autobiography tells us less about the state of Marischal College than about Turnbull’s restless character—it was a restlessness that dominated his life. In 1727 he left his position and received from the college an honorary LLD (doctorate of laws), the first such degree awarded by Marischal.
For the next fifteen years Turnbull held a series of short-term jobs, principally as a private tutor. It was an age when the grand tour was in fashion, marked by educational visits to the great capital cities of Europe, and usually culminating in a stay in Rome. As a private tutor he traveled widely, particularly in the Netherlands, France, Germany, and Italy. For the first five of those fifteen years he was tutor to Andrew Wauchope of Niddry, in which role he took his charge to Edinburgh, Groningen and Utrecht, the Rhineland, and France. But by 1733 he was back in Britain. In that year he matriculated and took his BCL degree (bachelor of civil law) at Exeter College, Oxford, conformed to the Church of England, and evidently cultivated clerical contacts assiduously. During the period 1735–37 he was for part of the time in Italy, again as a private tutor, this time to Thomas Watson, son of Lord Rockingham. Between the years 1727 and 1739 Turnbull had spent far more time outside Scotland than in it, and for a significant part of the period had lived in England. He was a deeply religious man, and in 1739 he was ordained into the Church of England, even though he had been raised in a Scottish Presbyterian family. In 1742 he was appointed rector of the parish of Drumachose in Ireland, an appointment he held until his death in 1748, although he did not spend much time there. His preference for travel reasserted itself; however by then, as we shall see, health considerations may also have played a role. In 1744 he returned to Italy where, among other things, he was involved in the covert gathering of information on exiled Scottish Jacobites.2
Turnbull was a prolific writer, with a particular interest in the themes of morality, religion, and liberal education.3 His earliest publication was a graduation thesis on the need for moral philosophy to be accepted as a science along with all the other empirical sciences, and to be developed with the aid of the same methodology as that employed for the other sciences.4 This theme recurs in his writings and is especially conspicuous in the present work.
The relation between the two volumes of The Principles of Moral and Christian Philosophy (1740), separately entitled Principles of Moral Philosophy and Christian Philosophy, respectively, is problematic because the first volume does not declare itself on the title page to be volume one, whereas the second volume does declare itself to be volume two, but only so declares itself in some copies, not all; and where the title page bearing the composite title The Principles of Moral and Christian Philosophy does appear in volume two that page has been glued in as a separate leaf and is plainly not part of the original printing plan. The reason for this is almost certainly that John Noon, the publisher of volume two,5 thought belatedly that Turnbull’s new work, Christian Philosophy, would have a better chance of commercial success if it were marketed as volume two in relation to the Principles of Moral Philosophy. But even if the composite title represents a marketing ploy, there is nonetheless an impressive unity of purpose to the two volumes taken together; in an obvious sense the second takes up and advances the discussion of the first. And there is little doubt that the two volumes were seen by Turnbull himself as two parts of a unitary work.
Furthermore, the first volume ends with an “advertisement” declaring: “So soon as the Author’s Health permits, will be published, CHRISTIAN PHILOSOPHY: or, The CHRISTIAN DOCTRINE concerning PROVIDENCE, VIRTUE, and a FUTURE STATE, proved to be perfectly agreeable to the PRINCIPLES OF MORAL PHILOSOPHY.” And Christian Philosophy does indeed seek to do exactly what the advertisement declares. It is therefore probable that, whatever the publisher’s motive for inserting the composite title in some copies of volume two, the two volumes were, according to the author’s intention, a single book.
In light of the advertisement it might be speculated (without being strongly urged) that the discrepancy in title pages may be related to Turnbull’s poor health; perhaps at the time of going to press with volume one the publisher was uncertain whether he would ever see the second volume. The nature of his illness is unclear. In a letter to Thomas Birch dated 7 April 1739, Turnbull had said he had a bad cough and that this was a new illness; and again on 4 February 1740 to Birch, he described himself as “seriously ill.” It might be conjectured that he was suffering from bronchitis or tuberculosis, but there is at present insufficient evidence. In the earlier of the two letters he comments that he is revising “a work which has long lain by me called the Moral philosopher . . .” and adds that he plans to revise the work that summer.6 If his publisher was aware of these medical details, as seems probable, he might well have been doubtful of his prospects of getting the second volume and consequently did not call the first “volume one”; only be latedly could he publicly acknowledge the unity of the work by adding the composite title.
In the preface to volume one Turnbull declares that aside from “a few things taken from late writers” the work is the substance of several pneumatological discourses that he had read more than twelve years earlier to students of moral philosophy, and he adds that the lectures were delivered at the time of publication of his two “theses,” that is, the public orations he delivered in 1723 and 1726 on the occasion of the graduation of his first and second cohorts of students.7 It is almost certain, therefore, that the young Thomas Reid heard the lecture-room version of Turnbull’s Principles of Moral Philosophy, and this points to Turnbull’s place in the early stages of the Scottish school of common sense philosophy. But quite aside from the probability that Turnbull had a major influence on Reid, The Principles of Moral and Christian Philosophy is of great interest in itself for the doctrines it develops.
Turnbull indicates what he himself regards as his true intellectual context by mentioning some of those who have influenced him. He singles out John Clarke’s Boyle lectures, Bishop Berkeley (mainly the Treatise Concerning the Principles of Human Knowledge), Lord Shaftesbury’s Characteristicks, Bishop Butler’s Analogy of Religion, Alexander Pope’s An Essay on Man (a work which had just been defended, to Turnbull’s delight, by William Warburton, a theologian of whom Turnbull strongly approved), and Francis Hutcheson—“one whom I think not inferior to any modern writer on morals in accuracy and perspicuity, but rather superior to almost all” (p. 14). While, on the basis of Turnbull’s own words, he is sometimes said to be particularly indebted to Hutcheson, it should be noted that Turnbull’s earliest publication, the graduation oration of 1723, predates Hutcheson’s earliest publication by two years and shows Turnbull already well set on the course he was to pursue for the rest of his writing days. The probability is that Turnbull and Hutcheson, educated in the same philosophical-theological canon and relying otherwise on their own native genius, reached rather similar conclusions without either having a great influence on the other.
Shaftesbury may have been a much greater influence on Turnbull than Hutcheson was. Shaftesbury’s importance is indicated by Turnbull’s early membership in the Rankenian Club (founded 1716 or 1717), an Edinburgh society composed mostly of young men preparing for the church or the law, who were particularly interested in Shaftesbury’s ideas and wished to create a forum to discuss them. Shaftesbury’s writings were also the focus of attention of the circle of thinkers who gathered round Lord Molesworth in Dublin, and it is therefore of interest that Turnbull, though never a member of the circle, maintained a correspondence with Molesworth on the subject of the relation between liberty, education, and the need to raise standards in the universities.
On the highly informative title page of the Principles of Moral Philosophy, Turnbull quotes Sir Isaac Newton’s Opticks book 3: “And if natural philosophy, in all its parts, by pursuing this method, shall at length be perfected, the bounds of moral philosophy will also be enlarged.” In a way this says it all. Turnbull places moral philosophy not outside but within natural philosophy. Natural philosophy is an empirical study of nature pursued by the method of observation and experiment, and for Turnbull, as for Newton, human minds, which are the proper object of the study of moral philosophy, are parts of nature. In that case the moral philosopher should rely on observation and experiment as his principal means of discovering the powers, affections, and operations of the mind. By such means the laws governing the human mind will be laid bare.
Natural philosophy is an investigation into the laws governing the behavior of things in the natural world. The laws are discovered via a search for uniformities in behavior. But Turnbull believes it is possible not only to discover the laws of nature but also to demonstrate their inseparability from a set of values, for the laws play a part in the production of the goodness, beauty, and perfection of the natural world. And the crucial point for Turnbull is that this is true whether we are speaking of the corporeal world or the moral world, that is, the world of spirits, human and otherwise. The principal objective of volume 1 of the Principles, therefore, is the identification of the laws of human nature and the demonstration that they serve the good, both the individual good and the good of the whole moral system. Insofar as the laws of nature, so to say, deliver a world that is good and beautiful, and insofar also as the laws are not themselves beings with intellect and will capable of intentionally delivering such a world, they have to be seen as pointing to a divinity beyond the natural world that they structure, a being who does have intellect and will, and who has a providential care for the world he created. The laws are therefore God’s instruments created to form a world that measures up as well as any world could to his goodness.
From Turnbull’s perspective, indeed, from that of almost every theologian of the Western tradition, the goodness of the world is a very imperfect representation of God’s goodness. But though imperfect, it is the best possible for a created world, and it is for this reason that Turnbull repeatedly refers to the world’s “perfection.” Furthermore, though always aware of the limits of our intellectual powers as we seek insight into the mind of God, Turnbull thinks that progress in this quest is possible because we can make discoveries regarding the natural world and especially regarding the laws of nature as statements of God’s intentions for this world. In this sense Turnbull’s thinking in the Principles is in line with that of his colleague and friend at Marischal College, the mathematician Colin Maclaurin,8 as well as that of a number of other leading contemporary scientists, who believed that recent scientific discoveries, and particularly those of Newton, constituted the best possible evidence for the existence and the attributes of God. Turnbull holds that in this sense natural science spills over into natural theology, or rather natural theology is one of the facets of natural science, just as—so Turnbull indicates at the start of the Principles —natural science spills over into moral philosophy, or rather moral philosophy is one of the facets of natural science. For Turnbull, therefore, the three apparently disparate disciplines constitute a strong unity.
The first law Turnbull identifies is “the law of our power,” by which the existence or nonexistence of certain things depends on our will, and here Turnbull refers to the existence, or otherwise, of things whether in our minds only or in the outer world. For by an act of will we produce physical artifacts and we also have ideas—it is a matter of great importance to Turnbull that thoughts are no less subject to our will than are the movements of our limbs. In this sense we have “dominion,” though limited, in the corporeal world and the spiritual. Such dominion is a kind of liberty. With dominion over my limbs I am at liberty to move them, and when I exercise that dominion my limbs move not of their own accord but by my determination. Now there is a view that liberty and law are incompatible, for law encroaches upon and thereby constrains the scope of liberty. But Turnbull rejects this and argues, to the contrary, that it is only in a world governed by natural laws that beings such as us can be free. His underlying consideration is that a willed act implies both an object at which the agent aims and also an act that is the means by which the object is secured. It is necessary to know enough about how the world works to know what has to be done in order to secure the end willed.
The knowledge in question is scientific since it includes a grasp of the relevant natural laws. Turnbull affirms: “did not fire gently warm and cruelly burn, according to certain fixed laws ascertainable by us, we could not know how to warm ourselves without burning” (p. 58). It is by a like insight into the laws governing the exercise of the mind that we come to acquire much of our knowledge and to contrive our moral improvement. In exercising our liberty, therefore, we use the laws of nature for our own purposes. I know that at a given distance the fire will warm me, not burn me or leave me cold, and I act accordingly. Speaking more generally, the laws of corporeal nature are good insofar as they enable us spiritual beings to realize our aims, all of which embody our values, for if we did not see what we aim at as valuable we would not aim at them.
Formally the same situation obtains with respect to the moral world. For we have dominion over ourselves no less than over things in corporeal nature. We have dominion over our own thinking, for once a thought comes into our head we can determine whether to pursue it or obliterate it, and we can will to start thinking through a given topic. We are therefore just as free in the inner world as in the outer. And in respect of the inner world also, there are laws of nature that we use for our own purposes: “Thus the knowledge of the passions, and their natural bearings and dependencies encrease our power and skill in governing them, by shewing us how they may be strengthned or diminished; directed to proper objects, or taken off from the pursuit of improper ones” (p. 71).
It is with such considerations in mind that Turnbull holds that this “moral anatomy” (i.e., the scientific study of the parts, powers, and affections of the mind) is not only a part, but the most useful part, of “natural philosophy” rightly understood. The goodness of the natural order is spectacularly evident in regard to our perceptual awareness of the world on which we act, and Turnbull comments on the fact that by a very early age we have learned sufficient of the laws concerning the magnitude and distance of objects to be able to judge of such things almost instantaneously. Without a grasp of the relevant laws we would be hopelessly inefficient at getting about in the world. The goodness of these laws is therefore evident.
A final example of a good law among the many that Turnbull spells out is the “law of custom.” The repeated conjunction of two ideas produces a habit of mind by which the subsequent occurrence of either idea draws in its train the other. In short, an “association of ideas” is formed by the mind. This law is as much a law of nature as are any of the laws regarding the corporeal world, and it is no less important for us. Indeed, without it we could not live as human beings, and certainly could not attain the level of culture that we reach; for all education is based on our ability to associate ideas one with another, so that ideas are available for instant recall. Without the law of custom, therefore, “we would plainly continue to be in old age, as great novices to the world as we are in our infancy; as incapable to foresee, and consequently as incapable to direct our conduct” (p. 127).9
Natural laws are operative throughout the natural world both corporeal and spiritual and, as Turnbull seeks to demonstrate in the Principles of Moral Philosophy, all those laws work on behalf of the good, and as such they point to God’s providential care for the world he created. Turnbull’s philosophy, which has fairly been described as a “providential naturalism,”10 is strongly argued, and was no doubt found persuasive by many in the two cohorts of students he taught at Marischal.
[1. ]Quoted in M. A. Stewart, “George Turnbull and educational reform,” in Aberdeen and the Enlightenment, ed. J. J. Carter and Joan M. Pittock (Aberdeen: Aberdeen University Press, 1987), 95–103; see 97. For much of the biographical information in this introduction I have relied on this article by Stewart and also on Paul Wood, “George Turnbull (1698–1748),” Oxford Dictionary of National Biography (Oxford: Oxford University Press, 2004).
[2. ]For information on his time in Italy see Wood, “George Turnbull.”
[3. ]For the last of these three, see Turnbull’s Observations upon Liberal Education, in All Its Branches (1742; reprint, ed. Terrence Moore, Indianapolis: Liberty Fund, 2003); also Turnbull’s A Treatise on Ancient Painting (London, 1740).
[4. ]See De scientiae naturalis cum philosophia morali conjunctione (On the unity of natural science and moral philosophy) (Aberdeen, 1723).
[5. ]He was one of the two publishers of volume 1, the other being Andrew Millar. It is not known whether Noon was the initiating bookseller for the first volume.
[6. ]I am grateful to Paul Wood for this information regarding Turnbull’s correspondence.
[7. ]De conjunctione (Aberdeen, 1723) (see note 4), and De pulcherrima mundi cum materialis tum rationalis constitutione (On the very beautiful constitution of the world both material and rational) (Aberdeen, 1726).
[8. ]Colin Maclaurin, An Account of Sir Isaac Newton’s Philosophical Discoveries (London, 1748), ch. 1.
[9. ]See A. Broadie, “The Association of Ideas: Thomas Reid’s Context,” Reid Studies 5 (2002), 31–53.
[10. ]A phrase first used by David Fate Norton in From Moral Sense to Common Sense: An Essay on the Development of Scottish Common Sense Philosophy, 1700–1765 (Ph.D. diss., University of California, San Diego, 1966), ch. 6.