Nietzsche and Hume: Naturalism and Explanation

For those who think in misinformed stereotypes, Nietzsche and Hume are the chalk and cheese of philosophy. Nietzsche is antiscience, a "postmodernist" and doyen of "Continental" philosophy; Hume, a hard-nosed protological positivist and hero of "analytic" philosophy. These two stereotypes are so misinformed it is difficult to know quite where to begin in dismantling them. But for those who rightly read Nietzsche as a naturalistic philosopher, Hume is a point of comparison for the obvious reason that, thanks to Norman Kemp Smith and Barry Stroud, naturalism is at the heart of Hume's philosophy.¹ How similar then are these thinkers?

There have been a very small number of synoptic and topic-based comparisons of Nietzsche and Hume,² but much, it seems to me, remains to be said; thus, this article is a prospectus for further work. The aim of this essay is to sketch the character of their shared naturalism and address two issues regarding it. One is their skepticism about causation. There is a prima facie problem here. A shared aspect of their naturalism involves attempts to explain, and explain causally, a whole host of phenomena by appeal to more minimal materials. Both, however, appear skeptical about causation itself, putting pressure on their explanatory aspirations. I shall show that there is no genuine tension for either thinker. The second issue I explore is the character of the explanations that they offer of different kinds of phenomena and what the philosophical ramifications might be. I should mention two caveats before we proceed. First, I am not here concerned to trace lines of influence from Hume to Nietzsche. Second, for reasons of space I will have to forego some of the detail necessary for a proper discussion, and a fortiori I shall be unable to defend fully the claims made for each philosopher. My main aim is instead to bring out what is common to their philosophical strategies.

Naturalism, Physiology, and Method

Both Hume and Nietzsche are "naturalists." But since philosophers as diverse as Spinoza, Quine, Aristotle, and John McDowell are "naturalists," this claim, while true, is relatively uninformative. To make some headway, we begin with what Kant said of Locke. Kant said that Locke offered a "physiology of the understanding" that, "in tracing its vulgar origins in common experience," amounts to an "attempt to cast doubt on the pretensions of the supposed Queen." Fortunately, says Kant, this "genealogy" is a "fiction."³ The notion of "fiction" in this context is more interesting than it may seem, but I will not address this issue here. Instead, putting fiction aside, I shall suggest that what Kant describes is the kernel of the naturalism of Hume and Nietzsche.⁴ They offer "physiologies of the understanding" and "genealogies" of concepts that have experiential origins. These explanations, furthermore, sometimes "cast doubt" on the pretensions of what is explained. In what follows I shall try to unpack this claim.

According to Brian Leiter, Hume and Nietzsche are speculative methodological naturalists constructing accounts of human nature "in order to explain various human phenomena."⁵ These general theories appeal to empirically determinable materials and principles that constitute their respective "physiologies." Obviously, their starting points are different. Hume appeals to "impressions," "association," "sympathy," "sentiment," "imagination," and other notions, whereas Nietzsche appeals to "drive," "ressentiment," the "will to power," and "affect." However different in substance their basic materials are, both Hume and Nietzsche conceive such materials to be continuous with the rest of the natural world. In Hume's case, the vocabulary of A Treatise of Human Nature is recognizable from the psychophysiology of the period, which is given a mechanical gloss and is exploited in the explanation of animal behavior.⁶ Thus Ephraim Chambers's massive 1728 reference work Cyclopaedia, or, an Universal Dictionary of Arts and Sciences contains entries on terms familiar to us from Hume such as imagination and association. Association, upon which the Treatise theory is built, was viewed as a mechanical and literally brute mechanism, which, according to thinkers like Hobbes, Descartes, Malebranche, Leibniz, and many others, governs the inferential mechanisms of reasonless animals. Similarly, much of Nietzsche's...