A DOMINANT POSITION IN MORAL PSYCHOLOGY combines two independently plausible views: the Humean theory of motivation and motivational externalism. (1) Motivational externalism is the denial of "internalist" claims that motivational force is somehow "built in" or "internal" to moral judgment. (2) The Humean theory of motivation, inspired by Hume's (1978/1888: 415) claims that reason is motivationally inert and is merely "the slave of the passions, and cannot pretend to any other office than to serve and obey them," holds that, whenever an agent acts, the motivational impetus for her action necessarily has its source in her desires. According to Humean externalism, moral motivation is the product of one's moral desires--the desire to be moral, perhaps (3)--which are distinct from or "external" to her motivationally inert moral judgments. (4)
Humean externalism is an attractive picture. Many philosophers find the arguments in favor of externalism to be highly compelling. These arguments are generally framed around plausible descriptions of human agents that fail to be motivated in appropriate ways, given their moral outlooks. In particular, a number of externalists have drawn on examples of severely depressed or listless agents who lack moral motivation. By demonstrating that there is a gap between the making of a moral judgment and one's being appropriately motivated, these examples are meant to establish that moral judgments are not themselves effective sources of moral motivation. Some further motivational attitude is needed to fill the gap. The Humean theory dovetails nicely with these externalist arguments. Many externalists endorse some form of cognitivism about moral judgments, according to which moral judgment is a species of belief. (5) On the Humean view, it should be no surprise that there is a gap between moral beliefs and motivation. Moreover, according to the Humean, desires can fill this gap in a way that suggests elegant explanations of both widespread moral motivation and motivational failures associated with severe depression. So to the extent that one finds the externalist arguments compelling, one might also be tempted by the Humean version of this view.
This essay argues that examples of severe depression offer no support for Humean externalism. If the argument based on depression is to undermine a philosophically important internalist thesis, it must make use of some unspecified general constraint on motivational states. However, at a reasonable level of abstraction, the assumption needed to complete the externalist argument is also likely to imply that even desires could not be motivational states. Thus, the argument from depression depends on an assumption that is incompatible with the truth of the Humean theory. Furthermore, the natural Humean responses to this anti-Humean argument turn out to be versions of strategies that, if successful, internalists could deploy in defense of their position. These responses are thus unlikely to be available to the Humean externalist. In short, at a reasonable level of abstraction, one of the key motivations for externalism undermines, rather than supports, the Humean theory.
Internalisms and Externalisms
In the opening line of The Language of Morals, R. M. Hare writes: "If we were to ask of a person 'What are his moral principles?' the way in which we could be most sure of a true answer would be studying what he did." Albeit somewhat overstated, Hare's observation is that we regularly express our moral outlooks through our actions. A student who thinks that cheating is wrong might decide not to copy answers from another's exam, though there is little chance of being caught. A philanthropist might reasonably explain her charitable activities by insisting that successful people have a responsibility to give back to their communities. When asked, an omnivore is likely to argue that there is nothing morally wrong with eating meat. That people generally try to live by their moral principles is supposed to be a perfectly mundane fact about our moral lives.
Internalists and externalists both typically accept that moral assessment is linked to motivation in important ways. Their dispute is over the precise nature of that connection. Though usually qualified, the paradigmatic internalist claim is that the presence of some appropriate level of motivation is a necessary condition for sincere moral appraisal. In the words of Gilbert Harman (1977: 33), "To think that you ought to do something is to be motivated to do it. To think that it would be wrong is to be motivated not to do it." (6) Formally, we might present this paradigmatic version of internalism as a strong modal thesis:
Necessarily, if an agent judges that an action, [PHI], is right (good, best, obligatory, etc.) she will be motivated to [PHI]; likewise, if she judges that [PHI]-ing is wrong (bad, inferior, impermissible, etc.) she will be motivated to not-[ PHI]. (7) (Modal Internalism) has the following externalist counterpart:
It is possible for an agent to judge that an action, [PHI], is right (good, best, obligatory, etc.) while not being motivated to [PHI]; likewise it is possible for an agent to judge that [PHI]-ing is wrong (bad, inferior, impermissible, etc.) without being motivated to not-[ PHI]. (8) (Modal Externalism) is one way of characterizing a standard externalist thesis. But externalism is also frequently presented in slightly different terms, as a positive explanatory thesis about the source of moral motivation. According to this alternative characterization, externalism holds that motivation to act morally comes from something outside of or "external" to the agent's moral views. For instance, Thomas Nagel (1970: 7) describes externalism as holding "that the necessary motivation is not supplied by the ethical principles and judgments themselves, and that an additional psychological sanction is required to motivate our compliance." Moral judgments play a role in explaining moral action, but not as the source of motivation. One's moral principles indicate what compliance looks like, but something beyond those principles must generate the motivation to comply. More precisely, this alternative version of externalism endorses the following explanatory thesis:
Whenever an agent engages in some motivated action, [PHI], the complete explanation of her action must appeal to some psychological state, distinct from her moral judgments, that serves as the ultimate source of motivation to [PHI]. Humean externalists endorse this explanatory picture, adding that the "psychological sanction" must be supplied by a distinct passion or desire. According to Humeans, all action is the product of two different kinds of mental states. Motivational states determine our aims or goals, and have "pull" or "oomph" to "push" us toward achieving those aims--these are the sources of motivated action. Informational states, by contrast, simply offer a view about what the world is like--they lack motivational force of their own, but instead tell us how likely it is that possible actions would promote the ends determined by our motivational states. Humeans claim that only desires and other passionate states can play the motivational role; beliefs and other cognitive states play only the informational role. Moreover, on this view, a desire cannot be generated by any rational process (like reasoning) without some preexisting motivational state playing a role in generating it. (9) It follows that the explanation of any rational action needs to appeal to some desire (or desires) as the ultimate source of motivated action. Humeans are thus committed to the following:
Necessarily, whenever an agent engages in some motivated action, [PHI], the complete explanation of her action must cite one or more of her desires as the ultimate source(s) of motivation to [PHI]. We can understand why externalists might be attracted to (EXPLANATORY Humeanism). If some extra "psychological sanction" is needed to motivate compliance with one's moral principles, desire is a likely candidate for such a state. This explanatory view is present in David Brink's (1986: 31) systematic defense of externalist moral realism when he suggests that moral motivation is the product of "deeply seated and widely shared psychological trait[s]," such as sympathy and the desire "to comply (even) with other-regarding moral demands." In a later essay elaborating his externalist position, Brink (1997: 13-14) explicitly endorses the more general Humean explanatory framework:
[T]he motivation of all intentional action, including moral motivation, requires the existence of independent conative state or pro-attitudes. ... I believe that fairness requires me to keep my promise to you, even at a significant personal cost to myself. I want to be fair. So I keep my promise to you, even at some cost to myself. ... But the motivation for my action does involve my more ultimate desire to be fair. ... If I did not have this more ultimate desire or commitment, my moral belief would lead nowhere (or elsewhere). This idea is echoed by Sigrun Svavarsdottir's (1999: 161) view "that moral judgments need to be supplemented by a distinct conative state (desire in the broadest sense of that term) in order to play a motivational role [and] this conative attitude is not necessarily present in those who make moral judgments." (10)
If we understand extemalism in terms of a positive explanatory thesis, like (Explanatory Externalism), we might see the debate between internalists and externalists...