Readers who have engaged with the highly original, iconoclastic, sceptical doctrines of Book I of the Treatise may be surprised, when they come to Book III, to encounter doctrines that markedly resemble those advanced by a number of Hume’s contemporaries. Hume was a member of the school of moral philosophy usually referred to as the “moral sentiment” school. The best known example of the work of this school is the 1759 book entitled The Theory of Moral Sentiments by Hume’s younger contemporary and great friend, Adam Smith, but there were a number of Scottish and English philosophers of the same period who held quite similar views.
The Book is divided into three quite unequal Parts. Part I, which is only 21 pages long, defends the view that moral distinctions are derived not from reason, but from an innate moral sense, or sentiment. We praise actions and approve of traits of character not on the basis of a rational argument but because we are naturally so constituted as to feel a sentiment of approbation when we observe actions or character traits of a certain sort. Hume does not argue that we ought to so approve; he simply observes that we do so, and undertakes by a wide canvas of our sentiments of approbation and disapprobation to discover the principles that seem to guide these sentiments. To summarize very briefly the result of an extended discussion, he concludes that we tend to feel a sentiment of approbation for actions or traits of character that are “useful or agreeable to ourselves or others.” This formula, which he repeats many times, has led some commentators to conclude that Hume is a utilitarian, but I think that is a mistake. Hume does not say that we ought to approve of what is useful or agreeable to ourselves or others. He simply observes that we do, and if someone [such as Kant, for example] were to argue that we ought not to base our moral approbation on these considerations, Hume would, I think, reply that in fact we do, and short of changing human nature, there is nothing we can do about altering our natural tendencies.
It is Part II that dominates Book III, running, as it does, for almost one hundred pages. Its title is ”Of justice and injustice,” and it contains the substance of Hume’s political philosophy. [Hume, by the way, was rather conservative politically, in the context of the British politics of his day, but that fact does not figure prominently in the arguments of the Treatise.]
Hume begins be arguing that justice is, in his terminology, an artificial, not a natural, virtue. His discussion is, at least to modern ears, somewhat strange sounding, but what is going on is easy enough to discern. In the new political philosophy of the 17th and 18th centuries – the political philosophy of Hobbes, of Locke, of Rousseau, of Kant, and of many lesser lights – one of the great points of disagreement was whether the rights and duties associated with property are natural, and hence bind us in a state of nature, prior to the establishment of a Commonwealth, or are artificial, and arise out of some pre-existing social contract. Locke and Kant are clearly committed to the view that the obligations of property bind us even in a state of nature [although, as I may explain in a subsequent tutorial, Kant is wrong about his own position], whereas Hobbes and Rousseau hold that property rights and associated duties depend for their moral bindingness on an original social contract. In this debate, Hume sides [if I may speak anachronistically, considering the dates of these various writers] with Hobbes and Rousseau, although not, as we shall see, on the basis of an original contract, which he considers a fiction.
Hume begins by observing that human beings, unlike lions or sheep, have natural abilities that are ill-suited to the satisfaction of their natural wants and desires. [There was a good deal of this sort of charming armchair speculative ethology in those days, not very reliable as a scientific guide to animal behavior but in its way rather suggestive about the human condition.] We are not particularly swift or strong, nor are we fitted out with formidable claws and a serviceable fur coat.
“’Tis by society alone,” Hume remarks, “[man] is able to supply his defects, and raise himself up to an equality with his fellow-creatures, and even to acquire a superiority above them.” He goes on, anticipating the arguments that Adam Smith would make such good use of thirty-six years later in his great work, An Inquiry into the Nature and Causes of the Wealth of Nations: “When every individual person labours a-part, and only for himself, his force is too small to execute any considerable work; his labour being employ’d in supplying all his different necessities, he never attains a perfection in any particular art; and as his force and success are not at all times equal, the least failure in either of these particulars must be attended with inevitable ruin and misery. Society provides a remedy for these three inconveniences. By the conjunction of forces, our power is augmented: By the partition of employments [ed. what Smith would call the “division of labour”] our ability encreases: And by mutual succour we are less expos’d to fortune and accidents. ‘Tis by this additional force, ability, and security, that society becomes advantageous.”
This view of the reasons for the appearance of the ideas of justice in society, elements of which can already be found in Hobbes’ Leviathan, eventually shows up, somewhat modified, in Rawls’ notion of “the circumstances of justice.” The idea is this: if each human being were fully capable of looking after his or her basic needs without any sort of cooperation, voluntary or forced; or if the natural powers and abilities of human beings were so dramatically different from one another that no self-interested basis for collaboration existed [but only brute domination]; or finally if human beings, rather like ants, naturally and unthinkingly acted in concert [my apologies to any E. O. Wilson fans], then conceptions of justice and equity and government would never arise.
The remedy for these deficiencies in the natural human condition, Hume, says, “is not deriv’d from nature, but from artifice.” In some way, human beings must enter into a “convention” or agreement to join their forces for the satisfaction of the self-interest of each. We might expect at this point that Hume would go straight to a theory of the Social Contract, echoing the arguments of Locke and Hobbes, with both of whom we was thoroughly familiar. But Hume considers stories about social contracts fictions. Indeed, at this point he makes a very interesting philosophical move, one whose full significance can be seen only after we have carefully studied and properly understood Kant’s moral and political philosophy, as well as that of Rousseau. This convention, Hume says, cannot be in the form of a promise, because promises themselves are the products, not the preconditions, of society. [He thus rejects completely the position articulated by Locke in the Second Treatise on Civil Government.]
The “convention” actually emerges naturally and gradually over time from a series of human interactions that prove to be mutually beneficial. Hume makes the point with a rather charming analogy: “Two men, who pull the oars of a boat, do it by an agreement or convention, tho’ they have never given promises to each other.”