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Hume on Practical Reason: How Skeptical Is He? by Alumnus Brad Griggs


Brad Griggs

Brad Griggs graduated from The Ohio State University in 2015 with a dual major in philosophy and psychology and minor in cognitive science. Brad began his career at Ohio State as a psychology major, when he began taking philosophy classes to fulfill general education requirements. He quickly felt at home in philosophy classes, and was compelled to add philosophy as a minor and, eventually, a second major.

Brad recounted, “Perhaps my best experiences studying philosophy were those moments during a lecture or reading when something counterintuitive suddenly seemed incredibly plausible -- like when I read Hume's account of causation for the first time.”

Brad’s paper, “Hume on Practical Reason: How Skeptical Is He?,” – reproduced below – won the 2015 Bingham Award for an outstanding undergraduate essay. Originally, he composed the paper for an upper-division course of Hume’s Treatise of Human Nature, taught by Professor Abe Roth.

Abe reflects, “Brad wrote two papers for my upper division course. Both papers were beautifully written and a pleasure to read. The way Brad handled Hume's text and pursued a line of thought reflected a level of sophistication that one would be pleased to see in a graduate seminar.”

Although studying Hume and receiving the Bingham Award were among the highlights of Brad’s philosophy education, he also cited classes with Professors Allan Silverman and Tamar Rudavsky as especially rewarding. Brad led what he describes as a “surprisingly well-received” class discussion on Jean-Paul Sartre's being-for-itself, in a course on phenomenology taught by Rudavsky, and his well-received written work for Silverman was instrumental in convincing him to undertake a philosophy major.

Currently, Brad is working in Columbus while preparing to apply to MA and PhD programs in philosophy. In his free time, he enjoys traveling whenever possible (including, earlier this year, a two-week stay in Japan), making and listening to music and reading comic books.

Hume on Practical Reason: How Skeptical Is He?

One of David Hume’s most notable philosophical discussions is his account of practical reason in, A Treatise of Human Nature. Here, Hume criticizes the traditional depiction of reason opposing passion in the will to action. He notoriously claims that such an opposition can never exist, because one’s ends are determined solely by one’s passions, and reason’s only function is to discover the means that help achieve one’s ends. Most of Hume’s discussion is fairly straightforward. However, there is some ambiguity in his skeptical description of reason’s role in action. Namely, the degree to which Hume is skeptical about practical reason is not entirely clear. Some scholars offer a normative reading that suggests Hume has an instrumentalist approach to practical reason, one that proclaims that one should take the necessary means toward one’s ends. Other interpreters have suggested that there is no normativity at all in Hume’s account of practical reason, that reason only delineates the means one can take in order to achieve one’s ends. In this paper, I will first consider the instrumentalist reading while showing that its supporting evidence is ambiguous and unconvincing. I will then consider the more skeptical reading while showing that its supporting evidence is relatively clear and persuasive. Finally, I will conclude with an endorsement of the skeptical reading of Hume’s account of practical reason.

           As already mentioned, Hume’s discussion of practical reason is nested within his argument for why reason can never oppose the passions in directing the will to action. Both the instrumentalist and the skeptical interpretations of Hume’s account of practical reason primarily rely on statements found in the first part of this argument, which aims to prove that reason alone can never influence the will. Therefore, in order to obtain a solid understanding of both readings, it would be prudent to track this argument until it reaches its contentious issue. Once the issue arises, the majority of the supporting evidence for each interpretation will already be available for consideration, and each case can be evaluated.

           In the interest of showing that reason alone cannot give rise to action, Hume delineates the functions of reason while claiming that none of these capacities involve motivating the will to action. He notes, “The understanding exerts itself after two different ways, as it judges from demonstration or probability; as it regards the abstract relations of our ideas, or those relations of objects, of which experience only gives us information” (T; SBN 413). In other words, reason can only do two things: make judgments (both demonstrable and probable) and discover relations between ideas and objects. Understandably, Hume does not put much effort into showing that neither demonstrative nor probable reasoning can motivate action, because such a claim is hardly controversial. However, he does note that such forms of reasoning only concern the realm of ideas and that the will to action is concerned with the world of objects that exist outside of one’s mind. Therefore, Hume purports, supposing an interaction between the two faculties is nonsensical (T; SBN 413). However, the second brand of reasoning – the one that discovers relations between objects in the world – does deserve a bit more attention.

             When considering reason’s ability to discover relations between objects, Hume sets out to prove that even this rational capacity is incapable of motivating action. Interestingly, this is the part of the discussion that instigates the divide between the instrumental and the purely skeptical interpretations of Hume’s account. Letting his hedonism shine, Hume proclaims, “’Tis from the prospect of pain or pleasure that the aversion or propensity arises towards any object: And these emotions extend themselves to the causes and effects of that object, as they are pointed out to us by reason and experience” (T; SBN 414). That is to say, our ends are determined by passions that correspond to the prospects of pain and pleasure. Reason’s function is to discover the means that will attain those ends by delineating the causal relations associated with those ends. Hume surmises that reason alone can never influence the will to action, because the most reason can do is discover such causal connections. He goes on to famously say, “Reason is, and ought only to be the slave of the passions, and can never pretend to any other office than to serve and obey them” (T; SBN 415). However, even with such strong proclamations regarding reason’s subservience to the passions, it still remains a bit unclear exactly how reason relates to action. In particular, one might wonder whether or not one ought to take the necessary, reason-delineated means toward ones ends (and, if so, whether or not this normative force constitutes some sort of rational influence on action).

           The instrumentalist portrait of Hume suggests that one does, in fact, have a rational obligation to follow the necessary means toward one’s ends. Kieran Setiya characterizes traditional Humean instrumentalism as advocating the claim that “once we have [passion-determined] desires, practical reason dictates that we take the proper means to their satisfaction” (Setiya, 1). The key word in this definition is “dictates.” If reason dictates that we pursue the means to our ends, then it seems that there may, in fact, be some normative force with which reason operates on our will to action. Hume never straightforwardly endorses this view. There are not any direct references to instrumentalism or rational requirements for action of any kind within his text. However, it seems that the instrumentalist line of thought might cohere with at least one of Hume’s passages concerning reason’s ability to discover causal connections.

            Hume’s potential support of instrumentalism is indirect but certainly plausible. He states that when reason discovers the causes and effects related to our ends, “our actions receive a subsequent variation” and that, although the impulse to act is not determined by reason, it is “directed by it” (T; SBN 414). The fact that one’s actions vary according to reason’s delineations and that actions are in some way “directed” by reason seems to imply that there is some executive force associated with reason’s discovery of causal relations. Perhaps reason, in one way or another, tells its agent what means should be pursued. However, Hume is quick to suppress such an interpretation as he concludes the very same paragraph by saying, “’Tis plain, that as reason is nothing but the discovery of this connection, it cannot be by its means that the objects are able to affect us” (T; SBN 414). Hume seems to want to say that although one’s passions can spread to the objects that reason discovers as causally connected to one’s ends, reason does nothing but reveal these objects to its agent, and it cannot draw an agent toward these objects in any way. Hume apparently meant that reason “directs” the will to action in only the mildest sense – that reason merely offers options for how to act given ones ends – and that one can choose to take the means to one’s ends or not take the means to one’s ends without any normative repercussion. Given these considerations, it seems that if the instrumentalist reading of Hume is to hold any weight, it should look elsewhere for support.

            Fortunately for the instrumentalist interpreter, there is a passage appearing later in Hume’s discussion that explicitly addresses the consequences of not taking the appropriate means to one’s ends. In fact, Kieran Setiya identifies this passage as the primary supporting evidence for the instrumentalist reading (Setiya, 2). Hume claims that “a passion can never, in any sense, be call’d unreasonable, but when founded on a false supposition, or when it chuses means insufficient for the design’d end” (T; SBN 416). One might be quick to suppose that if Hume thinks a passion is “unreasonable” when it somehow pursues insufficient means toward its end, then Hume also thinks that one should, by some rational requirement, pursue the appropriate means toward one’s ends. If this is true, then Hume certainly does seem to have an instrumentalist conception of practical reason. However, there does not seem to be any textual evidence to support this supposition. Nowhere in his discussion does Hume say that one should be reasonable or that one should not be unreasonable. He merely states that following insufficient means is, as a matter of fact, unreasonable. Furthermore, Hume also says that “a passion must be accompany’d with some false judgment, in order to its being unreasonable; and even then ‘tis not the passion, properly speaking, which is unreasonable, but the judgment” (T; SBN 416). For Hume, being unreasonable means nothing more than making a false judgment. It does not mean that one failed to meet a rational requirement or that one should have acted differently. Being unreasonable only means that one’s rational powers did not make true judgments. It seems that even the best supporting evidence for the instrumentalist interpretation fails to provide a convincing case for its own accuracy.

            With the most tenable arguments for the instrumentalist reading of Hume dispelled, it is time to shift the focus of this paper to the skeptical interpretation and evaluate its claims. In a sense, the skeptical reading is the negation of the instrumental reading. Its central claim is that there simply is no normativity associated with reason’s delineations of means. Rather than reason providing the means one should take to achieve ends, the skeptical interpretation asserts that reason only provides the means one can take to achieve ends. Christine Korsgaard identifies this skeptical interpretation as specifically being a “motivational skepticism” that expresses “doubt about the scope of reason as a motive” for action (Korsgaard, 1). On this view, reason can never prescribe or in any way motive action; it can only describe ways in which one can act in order to attain one’s ends. The previously supplied arguments against the instrumental reading seem to provide support for this line of thought. However, rather than simply reiterating the preceding counterarguments, it would be more compelling for the present case to look for further, more explicit support of the skeptical interpretation within Hume’s text.

            The endorsements for motivational skepticism are rampant throughout Hume’s discussion of practical reason. Phrases such as “reason alone can never be a motive to any action of the will” (T; SBN 413) seem to unequivocally advocate motivational skepticism. Hume claims that reason itself simply has no resources to motivate actions. Furthermore, Hume characterizes reason as having no affective ability whatsoever. He states, “Reason, for instance, exerts itself without producing any sensible emotion” (T; SBN 417). Not only does Hume deny a motivational ability of reason; he also denies that reason can ever give rise to any emotions (the sort of phenomena that do motivate action). Finally, and perhaps most strikingly, Hume proclaims, “’Tis not contrary to reason for me to chuse my total ruin… or to prefer even my own acknowledg’d lesser good to my greater, and have a more ardent affection for the former than the latter” (T; SBN 416). This quote obviously endorses the view that reason cannot tell agents what ends to have. However, as Korsgaard points out, it also seems to propose a further claim that reason cannot even rank our ends in a way that suggests what ends should be preferred over others (Korsgaard, 7). There is no question as to whether or not Hume’s text supports the skeptical reading. As the examples cited above show, he is indeed explicitly skeptical about reason’s ability to normatively prescribe or in any way motivate action.

            Despite the common attribution of instrumentalism to David Hume’s account of practical reason, there does not seem to be sufficient textual evidence to convincingly support this reading. Rather, it appears that Hume is entirely skeptical about reason’s ability to motivate one’s will to action. The most he allows reason to do is outline the possible means one can take to achieve one’s ends. This delineation is thought to place no requirements on the agent or motivate them to action in any way. Reason only provides a list of possible actions that one may or may not pursue. It should be noted, however, that despite reason’s apparent inability to require agents to take the means to their ends, it is not necessarily the case that such a requirement does not exist at all. Perhaps some other faculty of the mind (or even a source outside the mind) does indeed place such normative demands on one’s will to action. One might wonder if the existence of such a normative authority on action could possibly cohere with Hume’s staunchly empirical philosophy. This is a topic worthy of consideration, but, unfortunately, there is neither the time nor the space to pursue it here. For now, it seems sufficient to be satisfied with a clearer conception of Hume’s account of practical reason. With a better understanding of what thoughts Hume’s text actually expresses, future research into both Hume studies and practical reason in general should proceed more fluently.


Hume, David. A Treatise of Human Nature. Ed. L. A. Selby-Bigge and P. H. Nidditch. Oxford: Clarendon, 1978.

Korsgaard, Christine M. "Skepticism About Practical Reason." The Journal of Philosophy 83.1 (1986): 5-25. Ajjulius.net. 10 Apr. 2007. Web. 16 Dec. 2014.

Setiya, Kieran. "Hume on Practical Reason." Philosophical Perspectives 18.1 (2004): 365-389. Ksetiya.net. 16 June 2006. Web. 15 Dec. 2014.