2. Hume’s Response to Skepticism in THN 1.4.7

Having explored a variety of deep and troubling skeptical arguments in Book 1 Part 4, Hume leaves himself with a lot to do at the closing of Book 1. Two of his most important aims in this section are to avoid extreme skepticism, and to reject metaphysical excesses in the form of religious superstition. I argue that Hume’s treatment of these issues in the Treatise is less regulative than one might have hoped for.

Before we dive into THN 1.4.7, it is worth noting that Hume does seem to offer some epistemological advice earlier in Book 1 Part 4. However, such advice seems to be suspended in the light of the skeptical considerations that arise in THN 1.4.7. For instance, in THN 1.4.4.1, Hume distinguishes the justified “permanent, irresistible, and universal” principles of the imagination from the unjustified “changeable, weak, and irregular” ones; he also seemingly recommends “carelessness and in-attention” as a panacea to skepticism about the external world (THN 1.4.2.57). Astute readers of the Treatise will note the tension between these two recommendations, and indeed both seem to go out the window in light of the “dangerous dilemma” that Hume confronts in THN 1.4.7.6. The two horns of the dangerous dilemma are as follows: do we rely on “every trivial suggestion of the fancy” (THN 1.4.7.6), or reject them in favor of “the understanding, that is, to the general and more established properties of the imagination” (THN 1.4.7.7)? The former leads to credulity, but the latter leads to skepticism, as it is only in light of trivial propensities of the imagination—such as the inability of the mind to follow overly abstruse reasoning, and carelessness and inattention—that we can avoid skepticism with regard to reason (THN 1.4.1) and skepticism with regard to the external world (THN 1.4.2), respectively. Skepticism with regard to reason is circumvented by the inability of the mind to follow overly abstruse reasoning: “the action of the mind becomes forced and unnatural, and the ideas faint and obscure” when we attempt such reasoning (THN 1.4.1.10). In addition, as we have seen, skeptical worries about the external world are dismissed through “carelessness and attention” (THN 1.4.2.57).

Thus, both the recommendations in THN 1.4.4.1 and THN 1.4.2.57 must be reevaluated in light of the dangerous dilemma; we must look into THN 1.4.7, to find Hume’s considered recommendations on the topic of skepticism.Footnote ⁵ As I will argue, what Hume has to say in this section is less action-guiding than its counterpart in the Enquiry.

Having confronted the dangerous dilemma, Hume does not so much offer a general takedown of skepticism as he does a personal tour of his mental state. He notes that “reason is incapable of dispelling these [sceptical] clouds”; rather, he relies on nature to “relax this bent of mind” by dining, playing backgammon, and making merry with friends (THN 1.4.7.9). This engenders a rejection of “reasoning and philosophy” in favor of “the pleasures of life” (THN 1.4.7.10). In this splenetic and indolent mood, he offers what, following Don Garrett, has become known as the Title Principle:Footnote ⁶

Hume then feels the passions of curiosity and intellectual ambition arise within him.Footnote ⁷ These twin passions bring him back to philosophy (THN 1.4.7.12).

This discussion is hardly regulative. For one, in electing to take up an intimate first-personal viewpoint (one incongruous with the rest of the Treatise), Hume’s message takes a decidedly nonprescriptive tone. For another, in taking his return to intellectual pursuits to be guided by his own sentiments (rather than any more objective rationale), Hume has little to say to those who fail to share these sentiments. As Donald Ainslie argues, Hume’s discussion in THN 1.4.7 seems to primarily concern the question of whether we should philosophize.Footnote ⁸ In addition, while Hume’s inclinations lead him to philosophy, he certainly does not prescribe the same for everyone.Footnote ⁹ Indeed, Hume points to the “honest gentlemen” of England, saying “of such of these I pretend not to make philosophers, nor do I expect them either to be associates in these researches or auditors of these discoveries” (THN 1.4.7.14). Thus, Ainslie points out that for Hume, philosophy is entirely optional.Footnote ¹⁰

It might be objected that Hume’s first-personal description of his grapple with skepticism is meant to carry universal relevance. For instance, Charles Goldhaber argues that in THN 1.4.7, Hume deliberately uses humoral language to show his readers how they should temper their excesses and maintain a healthy doxastic state.Footnote ¹¹ According to such a reading, Hume offers his own (supposed) experiences as a lesson or template for his readers.

This reading is certainly a possibility, although its plausibility is harmed by the fact that Hume does not seem particularly invested in whether his readers follow his lead or not. At the close of the section, he has only the following to say to his readers:

If you feel like philosophizing, as the curious and intellectually ambitious Hume does, then go ahead—otherwise, follow your inclinations. There is a hope that the reader might have their “application and good humour” return, of course, but this vague hope is about as far as it goes.

It might be objected that this is not so much a dismissal of certain thinkers, as it is an action-guiding advice to cease philosophizing if one lacks the appropriate easy disposition, and instead to rest until one’s good humor returns.Footnote ¹² However, this reading assumes that one will, at some point, be capable of a disposition suitable for philosophy. However, as we have seen from his cursory treatment of the honest gentlemen of England, not everyone possesses this capacity: Hume explicitly recommends for such common thinkers to abstain from philosophy altogether. Of course, one might object that the honest gentlemen of England and their ilk are not Hume’s target audience. This is certainly true, but it underscores the intellectual elitism of the Treatise. At best, we can say that THN 1.4.7 is action-guiding only for the wise, but not the general public who do not already possess a proclivity or capacity for philosophy.

In short, Hume offers no concrete advice for the nonphilosophically inclined: he says nothing as to how they might be more disposed toward intellectual pursuits, nor how they might be wiser in their daily reasoning even if they elect against engaging in philosophical inquiries. “Wait until you feel like it, if you ever do” is hardly a basis for any sort of regulative epistemology.

One might think that the Title Principle, in prescribing when we are licensed to assent to our beliefs, might offer more guidance in this respect. In response, however, the idiosyncratic nature of the Title Principle is revealed by Hume describing it as one of his “sentiments of my spleen and indolence” (THN 1.4.7.11); this principle is idiosyncratic not only to Hume, but indeed to Hume only within a particular short-lived mood.

Moreover, even if one takes the Title Principle to offer a genuinely normative principle as to what we should believe,Footnote ¹³ it is still unclear that it is particularly regulative. The worry is that, as beliefs are simply lively ideas, the exhortation to believe lively reasoning that mixes with our propensities is somewhat trivial. Meeker argues that the propensity language is merely an elaboration of the liveliness language, concluding: “Once the structure of TP is grasped, it is difficult to see how any actual belief would be judged as unjustified.”Footnote ¹⁴ Ainslie draws a similar conclusion: “Garrett’s Title Principle gives us only what we do believe, not what we should believe.”Footnote ¹⁵

One might object that this response is too strong—in particular, it has been argued that the term “propensity” in the Title Principle, rather than being a mere redundancy of the liveliness language, refers instead to the passions.Footnote ¹⁶ While this might avoid blatant triviality, it still does not amount to a particularly regulative principle. Virtually, all of our beliefs mix with some passion or the other: religious superstition, motivated reasoning, and credulous belief in miracles, all are intimately bound with our passions. The only reasoning that would be obviously ruled out is the abstruse skeptical conclusions described in “Of scepticism with regard to reason” (THN 1.4.1), which would presumably count as the “false and extravagant” philosophy that is little more than the “cold and general speculation” (THN 1.4.7.13). However, for one, such reasoning is inherently unstable in the first place (THN 1.4.1.10), and for another, such reasoning is unlikely to darken the minds of even many among the most rigorous philosophers in the first place, let alone more prosaic thinkers.

The Title Principle does become action-guiding on an even stronger reading. Notably, Garrett has argued in a later work that the Title Principle applies only to “reason, as developed by its own self-reflection.”Footnote ¹⁷ In short, it is only reasoning that abides by the reason’s reflective standards that is endorsed when it is lively, ruling out flawed and unphilosophical reasoning. However, as I have pointed out, this reading seems unsupported by the texts as they stand.Footnote ¹⁸ For one, such a reading fails to endorse unreflective (but prima facie justified) immediate everyday beliefs, which Hume would presumably want to ratify. For another, Hume never explicitly qualifies the Title Principle in the way Garrett claims. In this, it is worth remarking that Hume notably refrains from appealing to the Title Principle in ruling out superstition in THN 1.4.7.13; this makes sense on the weaker reading of the Title Principle as unable to rule out superstition, but is difficult to reconcile with Garrett’s stronger reading.

Hume’s dismissal of extreme skepticism in favor of philosophy, then, is far from regulative. Nor does it seem that Hume ever intended otherwise, if his deliberate adoption of a first-personal viewpoint is anything to go by. What of Hume’s other aim of reining in metaphysical excesses in the form of religious superstition?

Hume famously recommends philosophy over superstition on the basis that it is the “safest and most agreeable” (THN 1.4.7.13), which tells us why we should adopt philosophy, but not so much as how we can do so.Footnote ¹⁹ For the purposes of this article, I wish to once again draw attention to his discussion of the honest gentlemen of England:

Hume here is undoubtedly poking fun at what he takes to be the unreflective masses of England, but the jibes occur in service of a serious point, which is a criticism of the flighty excesses of the philosophers of his day. In the passage above, Hume can only “wish” that the “founders of systems” would come to possess this “gross earthy mixture” embodied by the honest gentlemen of England that would rein in their overly metaphysical impulses. He continues by noting that without this quality, “a warm imagination” enters into philosophy, “specious and agreeable” hypotheses are embraced, and there can be no “steady principles” that “suit with common practice and experience” (THN 1.4.7.14).

Again, this is not particularly regulative. Rather than teach philosophers how to temper their metaphysical excesses, Hume resigns himself to merely lamenting their lack of some vaguely described quality of earthiness. On the whole, THN 1.4.7 offers an epistemology that is not particularly regulative along both dimensions. First, it is intellectually elitist, speaking only to a highbrow audience; second, the epistemic guidance that it does offer is less action-guiding than we might have hoped for.

3. Hume’s Response to Skepticism in EHU 12

The first and most obvious difference between EHU 12 and THN 1.4.7 is that the later work disposes with the first-personal description of his mental states. Instead, Hume offers a sober treatment of skepticism grounded in methodology. I argue that this literary shift corresponds to a deeper one: the discussion in EHU 12 is regulative in a way that THN 1.4.7 is not.

At a general level of description, EHU 12 shares the same aims as THN 1.4.7. Chief among these aims are to dismiss extreme skepticism, and to rein in metaphysical and religious excesses. We begin with Hume’s dismissal of skepticism in EHU 12.

Pivotal to Hume’s rejection of skepticism in EHU 12 is his dismissal of excessive antecedent skepticism in EHU 12.3. Briefly, excessive antecedent skepticism is the methodology of adopting a “universal doubt, not only of all our former opinions and principles, but also of our faculties”; crucially, this doubt occurs “antecedent to all study and philosophy” (EHU 12.3). Such skepticism seeks “some original principle, which cannot possibly be fallacious or deceitful” to guarantee the veracity of our faculties. However, such a methodology is doomed, as such “Cartesian doubt… would be entirely incurable” (EHU 12.3). Suspecting our beliefs and faculties even prior to any intellectual endeavors would condemn any intellectual project whatsoever to failure—we can only “advance” beyond any “original principle” by “the use of those very faculties” that we have already condemned to doubt (ibid.).

As some commentators have noted, Hume’s rejection of excessive antecedent skepticism represents an accordance of prima facie justification to our faculties.Footnote ²⁰ Indeed, Millican argues that EHU 12.3 indicates an acknowledgment of the failure of the argument of THN 1.4.1; this rejection of skepticism with regard to reason, which led to so much skeptical grief in THN 1.4.7, goes a very long way indeed to clearing out the threat of excessive skepticism.Footnote ²¹

Here, it is fruitful to contrast Hume’s rejection of skepticism in the Enquiry with the one we found in the Treatise. In the earlier work, Hume’s dismissal of skepticism took a first-personal form, as he charted his course from despair, to spleen and indolence, and finally to curiosity and ambition, leading to his return to philosophy. For those who did not share Hume’s disposition or sentiments, the exact moral is left somewhat unclear. All of this is absent from the Enquiry. Footnote ²² In its place, Hume offers concrete methodological advice for all: our belief systems must begin by according some default trust in our faculties. Recognize this, and the threat of excessive skepticism is severely blunted.

Let us turn now to Hume’s second aim of reining in our metaphysical excesses. While he rejects excessive antecedent skepticism, he thinks that a moderate version of antecedent skepticism will make us better reasoners by “preserving a proper impartiality in our judgments, and weaning our minds from… prejudices” (EHU 12.4). The methodology of moderate antecedent skepticism entreaties us to “begin with clear and self-evident principles,” “advance by timorous and sure steps,” “review frequently our conclusions,” and “examine accurately all their consequences” (ibid.). In doing so, we not only free ourselves from prejudice, but also guard against metaphysical excesses. Progress will be “slow and short,” but there will be progress nonetheless; these are “the only methods, by which we can ever hope to reach truth” (ibid.). Again, Hume’s recommendation to adopt this careful approach to our inquiries is a good, sensible, and actionable advice.

Hume’s counsel for avoiding metaphysical excess does not end there. Having endorsed the moderate form of antecedent skepticism, he goes on to investigate what he calls consequent skepticism—that is, skepticism that doubts the veracity of our faculties after we have found them to be fallacious via empirical investigation (EHU 12.5). He goes on to dismiss an excessive form of consequent skepticism that he calls Pyrrhonian skepticism. Finally, he recommends his own favored mitigated or academical skepticism, which is a moderate form of consequent skepticism. This mitigated skepticism takes two forms. The first recommends a methodology of general doxastic diffidence: “there is a degree of doubt, and caution, and modesty, which, in all kinds of scrutiny and decision, ought for ever to accompany a just reasoner” (EHU 12.24). The second recommends a methodology of limiting “our enquiries to such subjects as are best adapted to the narrow capacity of human understanding” (EHU 12.25).

Importantly, Hume notes that “a small tincture of Pyrrhonism” allows us to become more receptive to both forms of mitigated skepticism (EHU 12.24). The first kind of mitigated skepticism “may, in part, be the result of this Pyrrhonism, or excessive scepticism, when its undistinguished doubts are, in some measure, corrected by common sense and reflection” (ibid.). Hume notes that most people are “naturally apt to be affirmative and dogmatical”; however, becoming “sensible of the strange infirmities of human understanding” inspires “more modesty and reserve” (ibid.).Footnote ²³ Meanwhile, the second form of mitigated skepticism is also “the natural result of the Pyrrhonian doubts and scruples” (EHU 12.25). Our imagination is “naturally sublime” and seeks what is “remote and extraordinary,” but by being “once thoroughly convinced of the force of the Pyrrhonian doubt,” we will cease to be “tempted to go beyond common life” (ibid.).

Let us contrast this with the discussion of the honest gentlemen in the Treatise. As noted earlier, Hume does little more than “wish” for philosophers to enjoy a vaguely described “gross earthy mixture” (THN 1.4.7.14). Not much help here for those wanting to be better reasoners. The converse is true of the Enquiry. For one, here he clearly articulates not one, but two methodologies for tempering our metaphysical excesses via his two forms of mitigated skepticism. Nor does he stop there, going on to teach us exactly how to make ourselves more receptive toward these methodologies in the first place by recommending that we initially dip a toe into excessive skepticism (cautiously, mind!).

Indeed, Hume goes even further than this: he spells out exactly which domains of inquiry to maintain and which to excise. He recommends inquiries concerning “quantity and number” (EHU 12.27)—that is, mathematics—and matters “of fact and existence” (EHU 12.28), such as history, geography, astronomy, politics, natural philosophy, physics, and chemistry (EHU 12.30–31). In addition, he famously concludes the Enquiry by exhorting us to commit to the flames any inquiries that do not fall under these two heads, such as “divinity or school metaphysics” (EHU 12.34). Even for those who are unable or unwilling to follow Hume’s directions for discerning appropriate from inappropriate domains of inquiry, he takes the trouble to explicitly map out the epistemological space on their behalf.

One might worry that some of the action-guiding prescriptions that are found in EHU 12 stem from elements that are common to both the Treatise and the Enquiry, and so do not represent a point of difference between the two works. In particular, Hume’s rejection of areas of inquiry that go beyond Hume’s Fork such as “divinity or school metaphysics” (EHU 12.34) above might be seen to follow implicitly from Hume’s theory of relations (THN 1.3.1), or more generally from his content empiricism in THN 1.1.1.Footnote ²⁴ Recently, Millican has argued that Hume’s Fork in the Enquiry represents a significant departure from the theory of relations in the Treatise,Footnote ²⁵ but let us set this aside for the moment. Let us say that it is true that some of Hume’s prescriptions in EHU 12 might follow from various doctrines in the Treatise. However, the fact that the Enquiry, unlike the Treatise, draws out these implications as guidance for its readers is evidence that it is the more regulative work. Consider a recipe that just listed the ingredients for a chocolate cake, as opposed to one that gives you stepwise instruction; the latter is surely more action-guiding than the former.

4. The Easy and Abstruse Philosophy

As mentioned earlier, this article focuses on the comparison between Hume’s responses to skepticism in THN 1.4.7 and EHU 12. At least in this respect, it is safe to say the epistemology of the later work is more action-guiding that that of the former. There are other portions of the Treatise that present as somewhat more epistemologically action-guiding than THN 1.4.7, and it is worth making some brief remarks about them here. This provides a starting point for future work on this issue, and also facilitates the emergence of a broader narrative about the aims and scopes of the Treatise and Enquiry.

One ostensibly regulative aspect of Hume’s epistemology is the rules by which to judge of causes and effects offered in THN 1.3.15, which Hume describes as “all the Logic I think proper to employ in my reasoning” (THN 1.3.15.11). As foreshadowed by a footnote in THN 1.3.13.11, these causal rules stem from the philosophical second influence of general rules, which serve as a corrective to the unphilosophical first influence of general rules (THN 1.3.13.12).Footnote ²⁶

However, the action-guidingness of these rules should not be overstated. Hume himself recognizes the considerable limitations of these rules, remarking that they “are very easy in their invention, but extremely difficult in their application” (THN 1.3.15.11). He further remarks that the correct application of these rules requires “utmost constancy” and “utmost sagacity” in natural philosophy; our straits are even more dire in moral philosophy, where “there is a much greater complication of circumstances” (ibid.). In short, these rules are perhaps helpful if one is already sagacious, but for those of us who are not already wise, they seem to be of limited help in attaining wisdom. Indeed, Hume seems to take a decidedly fatalistic attitude toward the two influences of general rules more broadly, remarking that whether one abides by the unphilosophical first influence or the philosophical second influence is merely a matter of a person’s natural “disposition and character”:

If one is wise, then one will be guided by the second influence of general rules and thus act wisely; for the vulgar, hard luck!

Another portion of the Treatise that seems to indicate a regulative epistemology is Hume’s promise in the Introduction to improve the sciences. But again, on closer inspection, there is less regulation than there initially appears. Hume takes a rarefied stance in the Introduction, noting that his philosophy is “very deep and abstruse,” and indeed stating that it would be a “strong presumption against” his philosophy were it “easy and obvious” (THN Intro 3). As we have seen at the close of Book 1, Hume has little to say to those unable to follow him in his researches in Books 2 and 3 (THN 1.4.7.14). Again, Hume’s philosophy is at best regulative for the wise, but much less so for those who most need wisdom.

It is worth contrasting this attitude in the Treatise with a portion of the Enquiry that explicitly delves into deep and abstruse philosophy. Part II of Section 5 enters into a more technical discussion of belief in Hume’s psychological framework. However, here, Hume is very careful to isolate and signpost what he takes to be one of the more difficult sections of this work: he notes that “to readers of a different taste,” the “remaining part of this section is not calculated for them,” and can “be neglected” without issue (EHU 5.9). Those of us who teach will recognize this as a good pedagogy. Hume does not refrain from entering into more difficult materials, where appropriate, so as not to diminish the learning experience of more advanced readers, but where he does so, he cordons off the discussion such as not to unduly impair the learning experience of those readers unable to follow it. Moreover, he makes sure to emphasize the optional nature of this section, noting that “at this point, it would be very allowable for us to stop our philosophical researches” (ibid.).

Meanwhile, the Treatise makes no such effort. For one, as we have seen, it prides itself on the difficulty of the entirety of the work (THN Intro 3) rather than carving out a separate space for more challenging discussion. Now, as discussed earlier, in THN 1.4.7.14, Hume does ostensibly takes to be optional the reader following him in Books 2 and 3, which might seem superficially similar to his taking Section 5 Part II to be optional. However, there is a crucial difference between these two discussions, because while a reader of the Enquiry may have a fulfilling experience of the work despite skipping Section 5 Part II, there is no way for readers unable to follow Books 2 and 3 to have any meaningful sort of experience of the Treatise as a whole. (Extending the pedagogical analogy, this would be akin to telling students unable to follow the material to leave the classroom…!)

Even so, one might question if Hume’s prescriptions in EHU 12, like Hume’s rules in THN 1.3.15, also require a great deal of wisdom to employ.Footnote ²⁷ For instance, how “timorous and sure” should we be in our inquiries (EHU 12.4)? How much accurate examination of our conclusions are necessary before we can trust them (EHU 12.4)? What is the right degree of doubt with which we should operate (EHU 12.24)? The correct answers to these questions require experience and sagacity to discern. If this is the case, are Hume’s prescriptions in EHU 12 genuinely more action-guiding than those found in the Treatise?Footnote ²⁸

There is no denying that Hume’s prescriptions, whether in the Treatise or Enquiry, will be better employed by the wise than the foolish—indeed, this is just what it means to be wise. Nevertheless, Hume’s prescriptions in EHU 12 are still very much helpful to those who lack wisdom. Key is the empirical fact that, as a general rule, people tend to be overconfident in their own reasonings and opinions:

In this, a blanket exhortation to be more careful and modest in one’s reasoning and beliefs is generically useful. Any degree of vigilance in our reasoning (EHU 12.4), scrutiny in our conclusions (EHU 12.4), and diffidence in our beliefs (EHU 12.24) is, on the whole, going to improve one’s reasoning. Even the foolish person will almost always become a more responsible thinker by being more careful with their reasoning, reviewing their conclusions, and reducing their levels of certainty to some extent. An objector might worry that the foolish person may perhaps go too far with this advice; however, given our natural propensities, such an outcome is unlikely; even if one does go too far in this regard, it is implausible that they would go far enough that they would be epistemically worse off than they were in their original overconfident state. Doubtless, a wise person will employ Hume’s advice even more adroitly, but that is hardly remarkable.

This is perhaps worth contrasting with the rather dry rules by which to judge of causes and effects in THN 1.3.15. How much is, say, a rutabaga farmer really going to take away from these rules?Footnote ²⁹ However, tell the rutabaga farmer to be more careful in their reasoning, to think twice before jumping to conclusions, and to be less confident in their conclusions—such advice does seem like it might well improve their thinking. While some of the prescriptions in EHU 12 might need wisdom to be optimally employed, they are nevertheless going to be helpful for a broad audience. On the other hand, as we have seen, the Treatise is not even addressed to the foolish, but only to the wise.

I conclude with the following question: why might Hume’s epistemology be more regulative in the Enquiry than the Treatise? I offer a hypothesis below.

In the Enquiry, Hume distinguishes between the easy and abstruse philosophy. The easy philosophy treats its subjects as “active” beings, while the abstruse philosophy treats its subject as “reasonable” beings (EHU 1.2). In particular, the easy philosophy aims primarily at improving the conduct of its practitioners: it “moulds the heart and affections” and “reforms… conduct,” bringing its audience “nearer to that model of perfection which it describes” (EHU 1.3).Footnote ³⁰ On the other hand, the abstruse philosophy lacks this regulative capacity as is “founded on a turn of mind, which cannot enter into business and action,” and its principles cannot easily “retain any influence over our conduct and behaviour” (ibid.).

It should not be uncontroversial to classify the Treatise as a form of abstruse philosophy. It certainly regards “human nature as a subject of speculation,” and seeks “to find those principles, which regulate our understanding, excite our sentiments, and make it approve or blame any particular objection, action, or behaviour” (EHU 1.2). On the other hand, Hume, in the first Enquiry, characterizes his project as a union of the easy and the abstruse philosophy, thus hoping to reconcile “profound enquiry with clearness, and truth with novelty” (EHU 1.17). The aims of understanding human nature remain in the Enquiry, but Hume seeks to accomplish more in this later work; he also seeks to effect change in his readers.

Unlike most other forms of easy philosophy, however, Hume’s aims are not moral in nature, but epistemological, in keeping with its status as a partly abstruse philosophy exploring the fundamental psychological architecture of the mind. He aims to drive out “superstition,” showing that “human understanding… is by no means fitted for such remote and abstruse subjects” (EHU 1.12). In addition, he explicitly repeats this aim when characterizing his project as the union of the easy and abstruse philosophies:

This, I venture, explains why Hume’s epistemology is more regulative in the Enquiry than it is in the Treatise: the Enquiry, as a product of both easy and abstruse philosophies, aims to effect epistemological improvement in its readers; not just the readers who are already wise, but also those who lack wisdom but desire it.Footnote ³¹

It might be objected that EHU 1.17 only laments the unattainability of an ideal that unites the best of the easy and abstruse philosophies.Footnote ³² In response, that Hume genuinely conceives of his project as such a union can be substantiated by his 1739 letter to Hutcheson, whereby he sets out his ambition of making “a new Tryal, if it be possible to make the Moralist & Metaphysician agree a little better” (HL i.33).Footnote ³³ This new trial of uniting the anatomist and the painter is surely the Enquiries, which, of all the works in Hume’s corpus, best fits this description.

In short, Hume no longer aims at an exclusive readership in the Enquiry. In characterizing his philosophy in the Enquiry as partly easy, he situates himself alongside the likes of Cicero, philosophizing to the masses. In this, it is worth remembering that Hume’s initial title for the first Enquiry was the Philosophical Essays concerning Human Understanding. A Treatise is aimed at philosophers; however, the essay format, which Hume employs to great effect in his Essays Moral, Political, and Literary, is aimed at the public.

The picture that emerges from the preceding discussion is as follows. The Treatise is intended for the intellectual elite. In it, Hume shows disregard for the honest gentlemen of England (THN 1.4.7.14), he asks only those readers who share his disposition to follow him in his researches (ibid.), his rules by which to judge of causes and effects are at best only useful for those already wise (THN 1.3.15.11), and the Introduction makes clear that the Treatise is aimed at an audience who can follow deep and abstruse reasoning (THN Intro 3). On the other hand, the Enquiry speaks to a broader audience, being a union of the easy and abstruse philosophies, to the extent that Hume makes it a point to explicitly set out in clear and simple steps how to become better reasoners in EHU 12. Hume does not shy away from difficult philosophy in the Enquiry, but when he does so in Part II of Section 5, he explicitly quarantines this discussion to minimize disruption to more casual readers.

In this, it is worth noting that Hume’s earlier work seems decidedly more pessimistic than his later work regarding the possibility of intellectual improvement. In Book 3 of the Treatise, Hume claims that natural abilities—such as a quick apprehension, a clear head, a copious invention, a profound genius, and a sure judgment (THN 3.3.4.6)—are beyond our capability to change or influence: he contrasts our moral virtues from natural abilities, because the latter, unlike the former, are “almost invariable by any art or industry” (THN 3.3.4.4). Meanwhile, although Hume likewise discusses natural abilities (here referred to as “talents” or “intellectual endowments”) at length in the fourth Appendix to the second Enquiry, similarly making the point that they are not meaningfully differentiable from moral virtues, Hume here quietly drops the claim that they are invariable. Indeed, in an endnote to EHU 9.5, Hume enumerates a number of factors that explain differences in reasoning abilities. Some of these factors are innate, but many reflect a recognition on Hume’s part that cognitive improvement is a genuine possibility. For instance, “greater experience” of analogies, as well as “books and conversation” make one a better reasoner—and so Hume’s readers can effect intellectual improvement by engaging in reading and discussion. Other qualities of good reasoners are “great attention, accuracy, and subtilty,” as well as an avoidance of “haste or a narrowness of mind.” These two features are ones that Hume’s readers can easily implement: taking more time and attention with our inferences is something anyone can do. Given this more sanguine outlook regarding the possibility of intellectual improvement, perhaps it is not a coincidence that his later work demonstrates far more emphasis on regulative epistemology, aiming at a less rarefied audience.

Indeed, it is worth remarking that Hume’s conception of the very nature of philosophy changes between these two works. In the Treatise, philosophy refers to those speculations beyond “the sphere of common life” (THN 1.4.7.13), but in the Enquiry, Hume notes that “philosophical decisions are nothing but the reflections of common life, methodized and corrected” (EHU 12.25). The latter conception of philosophy is one intended for the masses; after all, it is through philosophy that they might become wiser.Footnote ³⁴ (Hume, 1751/Reference Hume and Beauchamp1998; Reference Hume and Greig1932; 1739–1740/Reference Hume, Norton and Norton2007a; 1748/Reference Hume and Millican2007b).