In the conclusion of my last essay, I noted that David Hume’s approach to ethics falls, generally speaking, in the tradition of “moral sense” theory. This approach is difficult to explain briefly, but I shall attempt to summarize some of its essential features, especially as found in the writings of the Scotch-Irish philosopher Francis Hutcheson (1694-1746) —a teacher of Adam Smith at the University of Glasgow, a seminal figure in the Scottish Enlightenment, and an important classical liberal who developed a theory of natural rights that was arguably the most sophisticated of its day.

Before proceeding I should explain why I am including a discussion of moral sense theory in this series on ethics, especially since this approach, though extremely influential during the eighteenth and nineteenth centuries (especially in Scotland and America), has found few defenders in modern philosophy. Although some modern theories of “moral intuitionism” may overlap to some extent with moral sense theories, the doctrine that we directly perceive virtue and vice through an internal moral sense has pretty much gone by the wayside. Nevertheless, regardless of our opinion of the technical features of moral sense theory, philosophers in this tradition remain valuable to read because of their stress on, and detailed analyses of, moral psychology. Moral sense philosophers repeatedly emphasized the indispensable role of introspection in understanding moral phenomena; and they beckoned readers to look within themselves to verify claims about a “moral sense.” What is the origin of our moral feelings and judgments? Exactly what is occurring inside us when we evaluate a person or an action as moral or immoral, good or evil? What feelings accompany such evaluations, and do those feelings precede or follow from our moral evaluations? What are the respective roles of reason and feelings when we pass moral judgments?

In their efforts to answer these and similar questions, moral sense philosophers had obviously engaged in a systematic process of introspection; and the better among them, such as Francis Hutcheson, were highly skilled in this endeavor. Hence, for me, the primary benefit of reading moral sense philosophers over the years is that they have improved my own introspective skills. When reading a particular argument, I frequently put down the book and reflect for a few minutes to see if my own internal experiences correspond with those of the writer. This method is virtually mandatory when reading moral sense philosophers, given the heavy emphasis they placed on moral feelings (or “sentiments”), if one wishes to gauge the extent to which one agrees with them. And even if one disagrees with a specific position, the questions raised by moral sense philosophers are at once interesting and difficult, so our attempt to answer their questions to our own satisfaction will often prove valuable for its own sake. Undirected introspection typically accomplishes little if anything of worth, since we tend to wander from one topic to the next. The writings of moral sense philosophers can provide a much-needed focus as we explore our inner life, and this process can dramatically improve our introspective skills.

I realize that the preceding observation may strike some readers as highly unusual, perhaps even as bizarre. In recommending that we read moral sense philosophers because of their introspective skills, have I not crossed the line from philosophy to psychology? Yes, exactly. But for many years I have urged people to study the ideas of some famous philosophers for their psychological value, regardless of how much we may disagree with the technical features of a particular philosophy.  The “great” philosophers were typically accomplished psychologists. For example, although I do not hold the philosophical theories of either Schopenhauer or Nietzsche in high regard, the same is not true of their psychological insights, which are frequently sagacious and highly suggestive.

Unfortunately, the psychological value of philosophical writings diminished considerably in the twentieth century, as philosophy increasingly became a highly specialized discipline with “experts” known as philosophy professors, and as psychology branched off to become its own specialized discipline. Nowadays most professional philosophers would be reluctant to cross the boundaries of their discipline by delving into moral psychology, feeling that they are not suitably qualified in that field, lacking as they do any academic credentials in psychology. Philosophers from an earlier age had no such reservations. They understood that psychology (in the informal sense of this label) depends a great deal on introspection, and that diplomas are no assurance of competence in this endeavor.

What of the common complaint that introspection is an unreliable method of gaining knowledge? This problem didn’t deter earlier moral philosophers in the least. Introspection, they believed, is essential to our understanding of moral phenomena. The fact that introspection is difficult and will sometimes lead to different people reaching incompatible conclusions—the same problems, they pointed out, also attend our experiences and analyses of the external world—simply means that we should hone our introspective skills as much as possible, not abandon introspection altogether.   

Now, let’s begin our discussion of moral sense theory by returning to David Hume’s famous passage about “is” and “ought,” found in his early book, A Treatise of Human Nature (1739). In my last essay I took issue with the conventional interpretation (known as “Hume’s Law”) of this passage. My interpretation was also advanced by Stephen Buckle in Natural Law and the Theory of Property: Grotius to Hume (Clarendon Press, 1991, pp. 282-83)—a book that I regard as one of the finest treatments of the modern natural-law tradition ever written. Buckle wrote the following about David Hume’s Is-Ought passage (quoted in my last essay):

…Hume is not there attempting to draw a distinction between facts and values, nor between facts and interpretations; nor is he claiming that there is an unbridgeable gap between ‘is’ statements and ‘ought’ statements. And, since these various misinterpretations have all at some time gone under the name, neither is he asserting ‘Hume’s Law’. The point of the passage is, more simply, that an adequate explanation of morality must include an account of why it moves people to action, and that the common moral theories, by ignoring the moral sense, fail this test. The gap between ‘ought’ statements and ‘is’ statements is a gap between obligations (and therefore actions) on the one hand, and facts and values on the other. The essential passivity, the instrumentality, of reason, guarantees the failure of the rationalist theories. Reason is a tool we use in order to achieve our ends. Our use of this tool depends on our purposes and so cannot explain them. The central point here could also be put by the insistence that an adequate moral philosophy much include a moral psychology, a psychology of moral action.

According to Buckle, “Hume’s ‘is-ought’ passage is undeservedly famous,” because his basic point had been made by previous moral sense ethicists: “Hume’s ‘is-ought’ passage is no more than a neat encapsulation of a commonsense of moral sense moral philosophy.” For example, we find essentially the same point in two books by Francis Hutcheson. Quoting Buckle once again (p. 283):

…Hutcheson charges the rationalists with being unable to explain some important words in the moral vocabulary: principally, ‘ought’, ‘must’, and ‘should.’ Hume follows suit….[Hume’s] account adds only a memorable final paragraph, a paragraph which brought him fame by coming to the attention of philosophers who read him for their own purposes, and misunderstood him accordingly. Hutcheson, spared the later fame, was also spared this fate.

The influence of Hutcheson on eighteenth-century moral philosophers (especially in Scotland and America) was profound. And Hutcheson, in turn, was influenced by the third Earl of Shaftesbury, who may be called the founder of moral sense theory. As I explained in my essay on Shaftesbury, he stressed the role of sentiments in our moral evaluations and conduct, while maintaining that reason plays a subsidiary role. Equally significant was Shaftesbury’s comparison between our moral sense and our aesthetic sense. As I wrote in my earlier essay:

Shaftesbury illustrated this point by comparing our prerational [moral] evaluations to our aesthetic sensibilities. We respond spontaneously to a beautiful object, even if we have no theory of beauty and have formed no explicit criteria to distinguish the beautiful from the ugly. In thus maintaining that our basic moral reactions are akin to our aesthetic responses, Shaftesbury established a perspective whose influence on eighteenth-century thought can scarcely be overestimated. In many subsequent philosophers we find the same comparison of the moral and aesthetic realms.

Shaftesbury’s ideas about a moral sense were sketchy and unsystematic. It fell to Francis Hutcheson to develop and defend moral sense theory in detail. The linkage between the moral and aesthetic realms is evident in the very title of Hutcheson’s early book, An Inquiry into the Original of Our Ideas of Beauty and Virtue (1725, 4^th ed. 1729). In the first part of this book Hutcheson argued (p. 10) that “there is some sense of beauty natural to Men; that we find as great an Agreement in their Relishes of Forms, as in their external Senses, which all agree to be natural; and that Pleasure or Pain, Delight or Aversion, are naturally join’d to their Perceptions.” Then, having established that there exists in humans a natural sense of beauty, Hutcheson went on to argue that it should be “no difficult matter to apprehend another superior Sense, natural also to Men, determining them to be pleased with Actions, Characters, Affections. This is the moral Sense, which makes the subject of the second Treatise.”

We find the same perspective in David Hume, who frequently referred to “moral beauty.” In An Enquiry Concerning the Principles of Morals (published in 1751, eleven years after Book III of the Treatise of Human Nature), Hume wrote:

The social virtues must, therefore, be allowed to have a natural beauty and amiableness, which, at first, antecedent to all precept or education, recommends them to the esteem of uninstructed mankind, and engages their affections. (Enquiries Concerning Human Understanding and Concerning the Principles of Morals, ed. L.A. Selby-Bigge, 3^rd ed., rev. P.H. Nidditch, Clarendon Press, 1994. p. 214.)

Why did Francis Hutcheson refer specifically to a moral sense, an internal sense analogous to our external physical senses? In An Essay on the Nature and Conduct of the Passions and Affections, with Illustrations of the Moral Sense (1728; 3^rd ed., 1742), Hutcheson wrote (p. 17): “If we may call every Determination of our Minds to receive Ideas independently of our Will, and to have Perceptions of Pleasure and Pain, A SENSE, we shall find many Senses besides those commonly explained.” Thus in speaking of a “moral sense,” Hutcheson meant at least two things: First, we have no choice in how we perceive virtue and vice in human beings. Just as we cannot will to perceive a red rose as black, so we cannot will to perceive a bad person as good, or will to view a vice as a virtue. Second, our perception of virtue in other people generates within us pleasant feelings, whereas a perception of vice generates unpleasant feelings. We experience these feelings automatically upon our perceptions of virtue and vice, without an intervening act of will. The internal moral sense, like the external physical senses, is “passive”; it simply receives and registers the relevant perceptions without changing them.

Thus does a moral sense meet the minimal requirements for what Hutcheson meant by a “sense.” But there is a third element of the internal moral sense that differentiates it from our external senses of sight, sound, and so forth. Our moral perceptions are accompanied by approbation and disapprobation—positive and negative attitudes that are not always present when we perceive physical objects and attributes by means of our external senses. The moral sense is that “by which we perceive Virtue or Vice in our selves, or others.” And, as before, our pro and con attitudes follow automatically from our perception of virtue and vice; these are not reactions that we can will into existence or that we have the power to change.

Although Hume rejected some parts of Hutcheson’s theory, the following passage illustrates his adherence to a fundamental aspect of the moral sense school:  

All morality depends upon our sentiments; and when any action, or quality of the mind, pleases us after a certain manner, we say it is virtuous; and when the neglect, or non-performance of it, displeases us after a like manner, we say that we lie under an obligation to perform it. A change of the obligation supposes a change of the sentiment; and a creation of a new obligation supposes some new sentiment to arise. But ‘tis certain we can naturally no more change our own sentiments, than the motions of the heavens…. (A Treatise of Human Nature, 1739, ed. L.A. Selby-Bigge, 1888, reprinted by Oxford at the Clarendon Press, 1964, p. 517).

Here we see Hume doing what he supposedly claimed cannot be done, according to the conventional defenders of the Is-Ought passage—namely, deriving moral obligations from facts of human nature (our sentiments). This is certainly food for thought.

How credible are the major doctrines of the moral sense school of ethics? I shall take up this issue in my next essay.