Smith criticizes Hume’s claim that reason cannot motivate actions, and explains how moral sense philosophers dealt with the problem of differing moral standards.

George H. Smith was formerly Senior Research Fellow for the Institute for Humane Studies, a lecturer on American History for Cato Summer Seminars, and Executive Editor of Knowledge Products. Smith’s fourth and most recent book, The System of Liberty, was published by Cambridge University Press in 2013.

In my last essay I sketched some features of moral sense theory, especially as found in the writings of Francis Hutcheson, a classical liberal who was an important figure in the early years of the Scottish Enlightenment. According to this approach, our basic reactions to moral behavior, such as when we approve of good actions and disapprove of bad actions, flow from our natural sentiments, not from our reason. Humans have an innate moral sense, one analogous to our physical senses, that enables us to perceive moral qualities and that causes us to respond to them automatically with either approbation or disapprobation.

In attempting to explain the essentials of moral sense theory, I may have bitten off more than I can chew. Although it is correct to call moral sense theory an important school of thought, especially during the eighteenth and nineteenth centuries, the differences between individual proponents of this perspective are considerable and would require, at minimum, an entire book to cover. It would be a complicated task, for example, to explain how David Hume agreed with previous moral sense philosophers (such as Hutcheson) in some significant respects, while differing from them in other significant respects—so I will focus in the first part of this essay on problems with Hume’s contention that “reason alone can never be a motive to any action of the will.”

Since morals, therefore, have an influence on the actions and affections, it follows, that they cannot be deriv’d from reason; and that because reason alone, as we have already prov’d, can never have any such influence. Morals excite passions, and produce or prevent actions. Reason of itself is utterly impotent in this particular. The rules of morality, therefore, are not the conclusions of our reason.

The key word here is “alone.” Reason alone, Hume repeatedly insisted, cannot motivate actions. Only a passion, or feeling, can cause us to act. Reason is inert in these matters, but it does serve two functions. First, if I desire an end which reason reveals to be nonexistent or impossible to achieve, then I may cancel my previous plan to pursue that goal. Second, if I desire an end that can be attained in a variety of ways, then I can use my reason to decide which means will be most efficient in getting what I want.

Let us grant the obvious point that desires are necessary to generate actions. We will not act to attain x unless we first desire x. Even so, how Hume could argue that reason is completely “inert,” “passive,” or “utterly impotent” in this area is a mystery to me, since the claim is so obviously false. Even the two functions that Hume attributed to reason belie his claim. If I desire x but my reason tells me that x is nonexistent or impossible to achieve, then reason, at the very least, can veto an action because of its futility. True, it may be said that I must want, or desire, to veto the action, x, that I otherwise would have taken, but where did this new want or desire originate, if not in my understanding? If I had not reasoned that my desire to pursue x would be futile, then my subsequent desire not to pursue x would never have come about.

Hume’s inconsistency is even more apparent in the second role that he assigned to reason. If I desire x and know this to be a goal that may be attained by several different means, then Hume conceded that reason may evaluate the relative efficiency of those means and choose the best one. Again, it may be said that I will not act on my decision without a desire that motivates my action—but, again, where did that desire originate, if not in my previous reasoning? If that reasoning had not occurred, I would have had no desire to choose one means over any other.

Of course, Humeans might reply that I would never have engaged in this reasoning in the first place without a preceding desire to determine the most efficient means to attain x, but this infuses desires with cognitive elements that Hume seemed to disallow. We cannot desire x without some cognitive belief about x. That is to say, unless we first know (or think we know) something about x, then to say that we desire to attain x will have no meaning for us. A pure desire with no conception of what will satisfy that desire would be nothing more than a vague feeling of uneasiness and frustration. In this case, we would not be motivated to satisfy the desire because we would have no idea of what to do. Only if we think about our vague desire will we be able to pin it down more precisely and perhaps figure out how to satisfy it. Of course, this sort of mental analysis will be motivated by our feeling of frustration and our desire to get rid of that frustration, but the frustration per se will not motivate any particular action until it is analyzed by reason.

If we agree with Hume that reason alone will not cause us to act, it may be said, with equal justification, that feelings alone will not cause us to act. This is so because, as I just explained, a vague feeling of dissatisfaction will give no indication of what to do. Only if we reason about a feeling of dissatisfaction will we be able to determine the action that stands the best chance of relieving our dissatisfaction.

Consider this scenario. I make a large purchase at a grocery store and pay with two $100 bills. When I receive the change, which should be a little over $20, I stuff the change and the receipt in my pocket without looking at them. Then, later that day, I discover that I got a little over $40 in change; the clerk overpaid me by $20.

As I reflect on what I should do, I remind myself that I don’t own a car, so getting back to the grocery store is a bit of a hassle. Moreover, as the store, not I, made the mistake, it is questionable how much responsibility I have to go out of my way to correct their mistake. But then I remind myself that the clerk may be held personally responsible by the store for the error and so may have to make up the deficit in the register from her own pocket. This possibility becomes the deciding factor for me. I decide to return the money.

This example is fairly typical of the kind of moral decisions that we make on a regular basis. It is far from clear‐​cut, given that it would be inconvenient for me to return money that I got because of another person’s carelessness. If I knew for certain that the store rather than the clerk would make up the loss, then I might have decided not to return the money at all, especially since it was not a significant amount. In any case, the moral reasoning involved and the conclusions different people might reach are not my main concern here. What I wish to focus on is the relationship between my reasoning about the situation and the action I decided to take. It seems clear that my reasoning ultimately motivated my action. If a Humean again insists that this is false, that it was my desire to return the money that motivated my action, I would reply as I did before. Although my desire was the proximate cause of my action, the desire itself was generated by my reason. That desire would never have existed at all except for the thought process that preceded it.

Consider this passage from A Treatise of Human Nature:

[R]eason, in a strict and philosophical sense, can have an influence on our conduct only after two ways: Either when it excites a passion by informing us of the existence of something which is a proper object of it; or when it discovers the connexion of cause and effects, so as to afford us means of exerting any passion.

Here Hume explicitly conceded that reason can excite a passion—in other words, that reason can cause a feeling which then motivates us to act. Here we have a causal chain from reasoning to feeling to action, and this normal sequence renders absurd Hume’s repeated assertions that reason is completely unable to motivate actions. Reason and feelings are not separate and insulated compartments of human consciousness. Rather, they are intertwined and continuously interact with one another. Hume, in this as in other matters (such as his celebrated theory of causation, which he ignores in his social and moral writings) is maddeningly inconsistent.

Are Moral Sentiments Universal?

What of the claim, common among moral sense philosophers, that moral judgements are ultimately rooted in our feelings of approbation and disapprobation—that, for instance, we condemn acts of deliberate cruelty not because of any intellectual assessment but because of an innate moral sense? An obvious objection to this theory (one raised many times by critics of moral sense theory) is that moral sentiments, which supposedly are part of human nature, vary dramatically among cultures, as we see with the vicious behavior of those radical Islamists who delight in burning, drowning, or torturing infidels. To their credit, Hutcheson and other defenders of a moral sense discussed this problem at length. They conceded that different moral standards are found in different cultures, but this merely means that what constitutes deliberate cruelty in one culture may not be regarded in the same way in other cultures. But once an action is identified as unnecessarily cruel in any culture, our innate moral sense kicks in and the feeling of moral disapprobation invariably follows.

Hume made a similar point when he observed that our moral feelings of approbation or disapprobation follow on the heels of our factual assessment of a situation. How we understand a situation will determine how we feel about it. When John Calvin insisted that heretics should be put to death, he defended his position as a defense of God’s honor, in effect. Thus, in Calvin’s view, to burn a heretic alive was a just punishment demanded by God, not an act of deliberate cruelty at all. This does not mean that Calvin lacked a natural aversion to what he regarded as unnecessary and deliberate cruelty. Calvin, like every other normal person, had a moral sense that generated a feeling of moral disapprobation of acts that he perceived to be cruel, according to his own understanding of the particular facts of a situation.

The upshot of this type of argument is that our moral sense does not specify which actions are moral and which are immoral per se. It merely generates pro and con feelings after our intellect has reached a conclusion about the context in which the action occurred. According to Hume, reason can tell us the facts, but it cannot generate a moral preference for some facts over others. Such preferences result from our innate moral sentiments, which generate our feelings that some actions are laudable whereas others are condemnable. This was the basis for Hume’s conclusion that the “rules of morality…are not the conclusions of our reason.”