David Hume and Friedrich Nietzsche are both moral psychologists in this sense. My aim here is twofold: to describe their basic answers to moral-psychological questions, and to explore the extent to which Nietzsche can be said to be distinct from Hume. This is a troubling question for anyone interested in Nietzsche as an original thinker, for both surface and depth readings reveal that his moral psychology has a strikingly Humean character. It is also a potentially troubling issue for "neo-Humeans", who constitute the numerical majority in analytic ethical philosophy. For if Nietzsche is close to Hume, then Hume is also close to Nietzsche, and Humeans may not be able to avoid confronting distinctly Nietzschean doubts about morality and social conduct.
1. Metaphilosophical Motivation
Both Hume and Nietzsche1 advocate a kind of naturalism. This is a weak naturalism, for it does not seek to give science authority over philosophical inquiry, nor does it commit itself to a specific ontological or metaphysical picture. Rather, it seeks to (a) place the human mind firmly in the realm of nature, as subject to the same mechanisms that drive all other natural events, and (b) investigate the world in a way that is roughly congruent with our best current conception(s) of nature:
Human minds are not strangers in nature, but inextricably parts of it. (Hume, T 1.2.1)
To translate man back into nature, to become master over the many vain and overly enthusiastic interpretations that have been scrawled over homo natural to see to it that man stands today... deaf to the siren-songs of old metaphysical bird-catchers who have been piping at him all too long: "you are more, you are higher, you are of a different origin!" (Nietzsche, BGE 230)
Furthermore, the motivation for this general position is common to both thinkers. Hume and Nietzsche saw old rationalist/dualist philosophies as both absurd and harmful: such systems were committed to extravagant and contradictory metaphysical claims which hinder philosophical progress. Furthermore, they alienated humanity from its position in nature—an effect Hume referred to as "anxiety"—and underpinned religious or "monkish" practises which greatly accentuated this alienation. Both Nietzsche and Hume believe quite strongly that coming to see ourselves as we really are will banish these bugbears from human life.
To this end, both thinkers ask us to engage in honest, realistic psychology. "Psychology is once more the path to the fundamental problems," writes Nietzsche (BGE 23), and Hume agrees:
the only expedient, from which we can hope for success in our philosophical researches, is to leave the tedious lingering method, which we have hitherto followed, and instead of taking now and then a castle or village on the frontier, to march up directly to the capital or center of these sciences, to human nature itself." (T Intro)
Hume and Nietzsche militate against the notion of a unified self, both at-a-time and, a fortiori, over time.
Hume's quest for a Newtonian "science of the mind" lead him to classify all mental events as either impressions (sensory) or ideas (copies of sensory impressions, distinguished from the former by diminished vivacity or force). The self, or ego, as he says, is just "a kind of theatre, where several perceptions successively make their appearance; pass, re-pass, glide away, and mingle in an infinite variety of postures and situations. There is properly no simplicity in it at one time, nor identity in different; whatever natural propension we may have to imagine that simplicity and identity." (Treatise 4.6)
Similarly, here is an infamous pair of passages from Nietzsche:
Just as the popular mind separates the lightning from its flash and takes the latter for an action, for the operation of a subject called lightning, so popular morality also separates strength from expressions of strength, as if there were a neutral substratum behind the strong man, which was free to express strength or not to do so. But there is no such substratum; there is no "being" behind doing... "the doer" is merely a fiction added to the deed—the deed is everything... But the way is open for new acceptations and refinements of the soul-hypothesis; and such conceptions as “soul as social structure of the instincts and passions” (GM 13, BGE 12)
For Nietzsche, the experience of willing lies in a certain kind of pleasure, a feeling of self-mastery and increase of power that comes with all success. This experience leads us to mistakenly posit a simple, unitary cause, the ego. (BGE 19)
The similarities here are manifest: our minds do not have any intrinsic unity to which the term "self" can properly refer, rather, they are collections or "bundles" of events (drives) which may align with or struggle against one another in a myriad of ways. Both thinkers use political models to describe what a person really is. Hume tells us we should "more properly compare the soul to a republic or commonwealth, in which the several members [impressions and ideas] are united by ties of government and subordination, and give rise to persons, who propagate the same republic in the incessant change of its parts" (T 261)
3. Action and The Will
Nietzsche and Hume attack the old platonic conception of a "free will" in lock-step with one another. This picture, roughly, involves a rational intellect which sits above the appetites and ultimately chooses which appetites will express themselves in action. This will is usually not considered to be part of the natural/empirical order, and it is this consequence which irks both Hume and Nietzsche, who offer two seamlessly interchangeable refutations:
"A quantum of force is equivalent to a quantum of drive, will, effect—more, it is nothing other than precisely this very driving, willing, effecting..." (GM 13)
"the distinction, which we often make betwixt power and the exercise of it, is without foundation... the terms of efficacy, agency, power, force, energy, necessity, connexion, and productive quality, are all nearly synonymous” (T 1.3.14)
Since we are nothing above and beyond events, there is nothing for this "free will" to be: it is a causa sui, "a sort of rape and perversion of logic... the extravagant pride of man has managed to entangle itself profoundly and frightfully with just this nonsense" (BGE 21).
When they discover an erroneous or empty concept such as "Free will" or "the self", Nietzsche and Hume engage in a sort of error-theorizing which is structurally the same. Peter Kail (2006) has called this a "projective explanation", whereby belief in those concepts is "explained by appeal to independently intelligible features of psychology", rather than by reference to the way the world really is1.
For example, Nietzsche believes that our erroneous concepts of selfhood and especially of "free will" serve a moral purpose: they are the creation of individuals (slave-moralists) for whom the concepts have aided the fulfillment of their drives. For Hume, our errors are more cognitive. In the case of our belief in free will, we mistake the operation of a calm but nonetheless strong psychological passion for the operation of a platonic rational will. In the case of selfhood, we project a unity on ourselves in the same way that we assume that objects in the world are unified and stable (when sensation tells us otherwise):
In order to justify to ourselves this absurdity, we often feign some new and unintelligible principle, that connects the objects together and prevents their interruption or variation. Thus we feign the continu’d existence of the perceptions of the senses, to remove the interruption; and run into the notion of a soul, and self, and substance, to disguise the variation. (T 220.127.116.11; SBN 254)
4. Freedom and Action
So, of what use is the notion of "freedom"? If compatibilism is the doctrine that our ordinary, pretheoretical, Platonic concept of rational freedom can survive under a view of humans as mechanisms, then neither Nietzsche nor Hume counts as a compatibilist. Rather, both endorse revised concepts of freedom, and thus of action itself. Hume and Nietzsche hold that while all choices are caused in some sense, we may nonetheless move towards what is today called a capability-conception of freedom. Here is Hume:
By liberty, then, we can only mean a power of acting or not acting, according to the determinations of the will; this is, if we choose to remain at rest, we may; if we choose to move, we also may. Now this hypothetical liberty is universally allowed to belong to every one who is not a prisoner and in chains. Here, then, is no subject of dispute. (EHU 8.1)
We may thus draw a contrast between two agents who both have a strong desire to lift a very heavy rock. One is strong enough to do so, the other is not, and thus in this particular instance, the strong one is free while the weaker one is not. Here is Nietzsche, again strikingly similar:
How is freedom measured in individuals and peoples? According to the resistance which must be overcome, according to the exertion required to remain on top. The highest type of free men should be sought where the highest resistance is constantly overcome... the free man is a warrior (Twilight, aph 38)
5. Consequences: Freedom, Human Nature and Morality
While Nietzsche follows Hume in viewing freedom as capability, he follows this thought to its seemingly logical conclusion and asserts a typology of persons. His "free spirits"3 are those who can discharge their wills and who seek always to overcome both society and even self. It is clear enough that such clearly contingent abilities will not be apportioned evenly throughout a population, and since freedom is so inherently desirable, it must be constantly fought for by and thereby earned by the strongest members of a population.
Hume's basically liberal political theory is meant to ensure that, through the internalization of moral virtues, each person can be free to express his or her drives. He bases this theory on an optimistic view of the content of natural human drives: we are naturally prone to feeling and acting on sympathy. Furthermore, as many neo-Humeans (see Bernard Williams, "Internal and External Reasons") are fond of repeating, education can inculcate virtuous dispositions in others so that we may all naturally gravitate towards mutual freedom of action.
So, while both thinkers deflate the role of reason in Human life and assert the primacy of affective drives, the content of those drives becomes the key point of contention between them. This, however, does not mitigate the extraordinary structural similarity between the moral psychology of Hume and Nietzsche. This point should thus be recognized by Nietzsche scholars: that a great number of his psychological ideas, both negative and positive, were anticipated by Hume in something very near to their precise form. Furthermore his method of offering "projective explanations" probably originated in its robust form via the same Scottish philosopher Nietzsche unwisely derided as "an abasement, a depreciation of the idea of a “philosopher”. (BGE 252)
Hume's optimism about human nature, however, is a shadow that looms over neo-Humean moral philosophy. This is because of Hume's somewhat naive lack of attention to both history and to present reality. It was precisely this myopia that Nietzsche caustically describes as characteristic of most philosophers. For it seems that humanity is capable of great natural sympathy and of unfathomable natural cruelty, and if reason cannot ultimately adjudicate between such drives, the moral quality of our world may be in constant jeapordy. It is significant that Harry Frankfurt, a paradigmatic neo-Humean ethicist, has written that:
So far as reason goes, the conflict between us may be irreducible. There may be no way to deal with it, in the end, other than to separate or to slug it out... this is a fact of life.(Frankfurt 2004, italics added)
The "facts of life" uncovered by our minimalist-naturalism have lead us to distinctly anti-moral conclusions. Here, the voice of Nietzsche whipsers in the neo-Humean's ear: why all the fuss about morality, then? Why the concern to vindicate some utilitarian or contractarian version of egalitarian moral theory when your foundational psychological theory has lead you straight to the doorstep of violence, inegalitarianism and power-relations?
I do not believe that Humeans cannot respond here (indeed, many have). Nor do I believe that Nietzsche's vision of a better society is one of great suffering, violence or oppression. I do believe, however, that a recognition of the powerful similarities between the two thinkers should provoke new and interesting questions for those in their respective philosophical camps.
1 Nearly any substantial reading of Nietzsche is controversial, and I am aware that the 'naturalist' reading is opposed by such diverse thinkers as Richard Rorty, Alex Nehemas and Gilles Deleuze. However, there is more than enough textual support in Nietzsche for both pro- and anti-naturalist readings, so my account may be usefully viewed as a Nietzschean moral psychology rather than an excavation of what Nietzsche himself thought. In my opinion, such an excavation is not possible with the texts we now possess.
2 Alasdair MacIntyre calls the offering of such an explanation "the activity of unmasking... that most characteristically modern of activities." (After Virtue 71-72) MacIntyre's work stands as an unmatched critique of Hume's role in the creation of our modern "emotivist" culture, with its associated fact/value dichotomy. This is the culture which has ceased to believe that its evaluations refer to anything other than the contingent drives of its members: in Nietzsche's terms, a culture which has killed God.
3 The German term here is frei Geist. This is important because the term "spirit" has religious overtones in our language. But geist is not translatable into a single term, it also strongly connotes mind and, crucially, motivation.