2. Godless Naturalism

The question of Hume’s religiosity immediately looms with the assertion that his system is godless, since Hume has been variously described as theist, deist, fideist, agnostic, and atheist. This is not the place to discuss my refutation of the first four categorizations and my qualified acceptance of the last, as I have done so elsewhere (Peckel, Reference Peckel2024). Darwin’s religiosity, by contrast, does not require such forensic analysis, as it is elucidated by the man himself in private correspondence. When pressed about his religious beliefs after the publication of On the Origin of Species, Darwin’s replies show frustration with the very question, and his stance is unequivocal: “I am sorry to have to inform you that I do not believe in the Bible as divine revelation, & therefore not in Jesus Christ as the son of God” (Darwin, Reference Darwin1880, Letter 12851). Despite rejecting revelation, the divinity of Christ, and doctrines of the afterlife, he resisted assigning labels to his religious belief or lack thereof, relegating the concern to a matter of private conscience and judgement: “every man must judge for himself between conflicting vague probabilities” (Darwin, Reference Darwin1879b, Letter 12088). The closest he comes to self-labelling involves the term his friend and priest-bashing bulldog, T. H. Huxley, coined: “I think that generally […] but not always, that an agnostic would be the most correct description of my state of mind” (Darwin, Reference Darwin1879a, Letter 12041).

We see that even agnosticism is embraced with reservations by Darwin, for the principal reason that he did not regard attaching a label to his belief necessary. Nor do I. What I label ‘godless naturalism’ is Darwin’s system, based, not on Darwin’s confessions as an unbeliever — though these certainly support that description — but on the structure and content of his thought. His system is godless, like that of Epicurus and Hume, independent of personal confessions of belief. ‘Godless’ and ‘atheistic’ appear synonymous, but they are not equivocal. Hume and Darwin, like Epicurus, do not begin with an antecedent commitment to atheism, as many scientific, evolutionary, or secular thinkers today might do. Indeed, they begin with openness to the possibility of theism or deism, yet end up with fundamental conflict between the constitution of the natural world and God conceived even in minimalist terms. This does not amount to direct denial of the existence of God, but is primarily a denial of the coherence of and need for God in explaining nature and guiding human conduct. God may therefore remain ‘existing’ in some other obscure sense — as the gods do in Epicurus — but is deprived of any meaningful role as a creative, causal, or providential force in the natural order and in our lives within it. In this sense, their systems are godless: Espying through a naturalist lens, they see less and less of the purpose or advantage of God in nature, until nothing of consequence to human understanding or conduct is left.

3. Unintelligent Design

That the intricate design apparent in the world and its creations is a thing to marvel at, and that such a design is present, is never denied by Hume or Darwin. To the contrary, it is expressly acknowledged because it is the effect whose cause needs explaining. An intelligent designer, proposed by Thomas Aquinas and canonized by William Paley in his Natural Theology, prior to Darwin’s Origin and after Hume’s Dialogues, had long been the dominant theological explanandum of that effect. Hume and Darwin skewer that idea in different ways, the first as a sceptical empiricist, the second as a natural scientist. While their mirroring attacks on intelligent design have been a major focus of comparative scholarship, an examination of the convergence of the ideas themselves as part of a unified system is wanting. This owes to the perceived necessity of justifying overlaps in terms of textual-historical exposure amid a dearth of relevant evidence. What follows instead grounds the convergent Hume-Darwin attacks on intelligent design in common premises found also in Epicurean philosophy in antiquity, which re-emerge out of commitments to the naturalist epistemological horizon and yield common inferences that are refined across that intellectual history.

This first node of convergence in the Epicurus-Hume-Darwin triad is visible in the hypothesis raised by Philo — Hume’s arguable mouthpiece in Dialogues — of a self-ordering system of nature that reaps design from chaos by virtue of the immense scope for trial, error, and gradual integration of successes that aeonic periods of time allow for.

Philo’s proposal is an exact rendering of the modified Democritean atomism of Epicurus with its doctrine of atomic “swerve” (see Lucretius, 1977, 2.216–2.293, 2.710–2.729). As Lucretius expresses: “our world was made by nature, when/ atoms, meeting by chance, spontaneously,/ and joined in myriad useless, fruitless ways,/ at last found patterns, which when thrown together/ became at once the origin of great things” (Lucretius, 1977, 2.1058–2.1062). Crucial to these proposals is that forms, while emerging out of random collisions of matter, are not arbitrary productions. If they were, the matter that is said to settle or find patterns would lack a framework for ever settling or finding patterns over time. As Lucretius maintains:

While motile matter is unguided, its realization into patterned forms is not ungoverned. Self-propelling atoms produce stable material forms under the permissible natural conditions and laws, with stability obtaining only after much atomic trial, error, and failed attempts. This explains why uncountable random atomic collisions require vast stretches of time until conditioned patterns of stability in the production of forms — or, in other words, the appearance of design — can emerge.

Like Epicurus, Lucretius, or any naturalist worthy of the name, Philo examines what is “actually the case with the present world,” and finds proof of this self-ordering materialist metaphysics in the “economy of things, by which matter can preserve that perpetual agitation, which seems essential to it, and yet maintain a constancy in the forms which it produces” (Hume, Reference Hume and Gaskin1993a, 8.6, p. 85). With a baseline of binding yet blind natural laws, plus a cosmic (as opposed to biblical) timespan, the cause of design is sufficiently accounted for, in turn rendering the postulation of an agent of purpose-guided creation — and, for Darwin, speciation — an entity beyond necessity. As Philo challenges, with such an immanent materialist metaphysics fully explaining the appearance of design without recourse to “any known voluntary agent,” the latter becomes a “hypothesis attended with no advantages” (Hume, Reference Hume and Gaskin1993a, 8.4, pp. 84–85). As Darwin biographers Desmond and Moore note, an identical thesis of autonomic creation and evolution is adopted by their subject, premised on an atomistic metaphysics in which atoms are self-organizing building blocks that do not require — and, in fact, negate — an intelligent ordering principle (Desmond & Moore, Reference Desmond and Moore1991, pp. 249–251). Darwin’s refinement consists in extending this thesis from material forms in general to species specifically. The emergence of new species is fully explained within the framework of such a materialist metaphysics, such that, echoing Philo’s objection from parsimony, by adducing “the plan of the Creator […] nothing is thus added to our knowledge” (Darwin, 1859/Reference Darwin and Appleman2001a, p. 153). Desmond and Moore provide a fitting description to capture this godless, as opposed to atheistic, thesis: For Darwin, “God was an absentee landlord, and nature self-sufficient” (Desmond & Moore, Reference Desmond and Moore1991, p. 479). While none of these accounts in Darwin, Philo/Hume, or Lucretius/Epicurus deny the existence of an intelligent designer outright, all render the role of such an entity in design superfluous at best and an ill-fitted explanation at worst.

Beyond proposing autonomic materialism and wielding Occam’s Razor to slash intelligent design, Philo unleashes a salvo of sceptical counters to shifting versions of the design argument defended by Cleanthes in Dialogues. These show that, ceteris paribus, there is no greater credibility to that hypothesis than to other possible contenders that deviate far afield of the theologically palatable; among them, a generational and vegetational principle, a finite and fallible God, and a God of mixed moral attributes (Hume, Reference Hume and Gaskin1993a, 7, pp. 78–83, 5.5, p. 68, 11.18–11.20, p. 114). A fourth possibility raises a key argument, which Lucretius foreshadows and Darwin rediscovers, against the very coherence of an (all-)intelligent designer given the surfeit of error in the world, which would have accumulated over aeonic time:

In an evocation that presupposes Philo’s insight, Darwin claims: “We see nothing of these slow changes in progress, until the hand of time has marked the long lapse of ages” (Darwin, 1859/Reference Darwin and Appleman2001a, p. 113). The ancestor of both these reflections is the Epicurean attack on anthropocentric creationist metaphysics, which Lucretius blames on ignorance of nature such as it presents itself to the senses, which ought instead convince us that “gods most certainly never made the world/ for you and me: it stands too full of flaws” (Lucretius, 1977, 2.180–2.181).

Here, as elsewhere, Darwin can be read as giving evidential proof to what Philo and Lucretius gave philosophical voice. He sees natural beings, both living and fossilized, as plain counterevidence to perfection in design, and even to progressive tendencies towards an absolute standard of perfection. The preponderance of palpable blemishes in the creative process and product reveals a system of abundant wastefulness, chance, and imperfections. As put in famous words to fellow scientist and sounding board, Joseph Hooker, while working on Origin: “What a book a Devil’s chaplain might write on the clumsy, wasteful, blundering low & horridly cruel works of nature!” (Darwin, Reference Darwin1856, Letter 169). Philo all but supplies the preface to such a book when he urges: “the whole presents nothing but the idea of a blind nature, impregnated by a great vivifying principle, and pouring forth from her lap, without discernment or parental care, her maimed and abortive children” (Hume, Reference Hume and Gaskin1993a, 11.14, p. 113). In these respects, Darwin was an unequivocal opponent of intelligent design metaphysics and Lamarckian evolution alike: “Nor ought we to marvel if all the contrivances in nature be not, as far as we can judge, absolutely perfect; and if some of them be abhorrent to our ideas of fitness” (Darwin, 1859/Reference Darwin and Appleman2001a, p. 165); against Lamarckian doctrine, “Heaven forfend me from Lamarck nonsense of a ‘tendency to progression’ ‘adaptations from the slow willing of animals’” (Darwin, Reference Darwin1844, Letter 3). (Earlier in his career, he opposed the related Aristotelian conviction in a Scala Naturae topped by humans (after God) by virtue of their intelligence: “It is absurd to talk of one animal being higher-than another. — We consider those, where the [intellectual faculties] […] most developed, as highest. — A bee doubtless would when the instincts were” (Darwin, Reference Darwin1837, B 74).)

Darwin extends his critique of the conviction in perfection or tendencies towards perfection in design to cases of ostensibly perfect adjustments of organic structures to functions: eyes for seeing, wings for flying, etc. The presumption of the design of organs or parts to a preassigned purpose, as watch hands to a watch, puts the cart before the horse: In nature, the parts come first and the function after, if it comes at all. Remarkably, this argument had been raised as far back as antiquity, in the philosophy of Epicurus:

Darwin steps in with the evidence, or the interpretation of the evidence, that proves this Epicurean attack on teleological design. In doing so, he turns the idea of a purposive blueprint on its head with the recognition of functions that are not expressed in the expected harmony with their structures, such as webbed feet that do not function for swimming, showing that such structures are as likely to fulfill other functions than their presumed ones as they are to fulfill no function at all (e.g., vestigial limbs, rudimentary organs, exapted structures, etc.) (Darwin, 1859/Reference Darwin and Appleman2001a, p. 143).

Darwinian biologist Ernst Mayr fittingly describes such facts as illustrating the “opportunism of evolution” (Mayr, Reference Mayr2001, p. 207). That opportunism — as opposed to teleology — of evolution unseats the conviction in an absolute standard of perfection in design, intelligently envisioned and engrafted on natural creations as by a Platonic demiurge. As Darwin stresses, well-fitted designs follow no standard at all, but are strictly relative to the conditions of life in a time and place, such that structures that appear to be finely tuned in one context are “not necessarily the best possible under all possible conditions” (Darwin, 1859/Reference Darwin and Appleman2001a, p. 141). With a principle that shows the perversion of Darwinian science by certain brands of Social so-called Darwinism, he concludes that: “Natural selection will not necessarily produce absolute perfection; nor, as far as we can judge by our limited faculties, can absolute perfection be everywhere found” (Darwin, 1859/Reference Darwin and Appleman2001a, p. 147.) In the last analysis, the Epicurean, Humean, and Darwinian attacks on intelligent design imply a more unsettling demand to unsee the absolute perfection of God as well. For the designer’s standard of perfection is nowhere seen in his design, and his design is meant to bear that standard. If God is permitted to remain existing, then it is only as an imperfect, unintelligent, and inconsequential creator with respect to his creation. And the same, we will see, goes for God’s role over his creatures.

4. Felicity and Utility

While Hume’s and Darwin’s interlocking assaults on intelligent design and in favour of a self-regulating, non-teleological materialist metaphysics stem from differing methodological vectors — one sceptical empiricist, the other empirical-scientific — their naturalized accounts of morals both derive from evolutionary anthropology. As Hume argues, the “foundations of ethics” concern a “question of fact, not of abstract science,” which depends on “the experimental method” to yield results (Hume, Reference Hume and Beauchamp1988, 1.10). He accordingly appeals to comparative anthropological and zoological facts, which reflects the same lens of investigation that defines Darwin’s Descent of Man. From common premises, they infer common conclusions concerning the foundations of ethics, which are refined through the enhanced scientific tools and availability of anthropological evidence of the Darwinian lens.

Larry Arnhart examines these overlaps in Hume and Darwin by identifying continuities with contemporaries like Francis Hutcheson and T. H. Huxley, respectively, and posits ancient rudiments of their naturalist ethics in Aristotle (Arnhart, Reference Arnhart1998). There is some textual-historical evidence for the Hume-Darwin connections, since rough jottings prove that Darwin read Hume’s Enquiry Concerning the Principles of Morals (Darwin, n.d.). The influence may have been amplified by J. S. Mill, even though Arnhart’s only mention of Mill is in an endnote (Arnhart, Reference Arnhart1998, Endnote 10, p. 387). And Hutcheson, himself drawing on ancient philosophy — albeit stoicism — did provide early inspiration for Hume by seeking the foundations of morals in human passions as opposed to ecclesiastic prescript (see Harris, Reference Harris2015, pp. 31–51).

The problem is that Hume breaks decisively with Hutcheson’s neostoicist ethics due to its conception of nature

Hume’s attack on teleological ethics is thus interwoven with his assault on intelligent design metaphysics: In one, he targets the purposive fitness of natural designs according to a rational blueprint, in the other, the purposive fitness of human nature according to a final cause for which it was created and which is attained through virtuous conduct. This comprehensively anti-teleological perspective puts Hume far closer to fellow irreligious naturalists like Baruch Spinoza and Thomas Hobbes than Hutcheson (cf. Harris, Reference Harris2015, p. 53). It also puts Hume at fundamental odds with the Aristotelian predecessor that Arnhart proposes, even if they coincide on certain incidentals. A stronger transhistorical predecessor on fundamentals exists in the godless naturalism of Epicurus, with the Epicurean, Humean, and Darwinian moral revaluations all forcing us to see more of our natural conduits of human happiness and less of the virtuous designs of God in human conduct.

As Hume exposits, humans naturally strive for conditions that ensure optimal balance of individual pursuits of felicity within a context of collective co-existence. That balance is maintained by the codes and institutions that best promote “public utility” to serve the net felicity of the whole, which is a common good beyond, yet encompassing, the individual, and provides the yardstick for moral judgements (Hume, Reference Hume and Beauchamp1988, 2.17, 2.22). One key philosophical aspect of this naturalization of moral motives and yardsticks is the dissociation of the “ultimate ends of human actions” from a rational ground (Hume, Reference Hume and Beauchamp1988, Appendix 1.18). But, if our moral compass lacks rational grounding, what proof backs his claim that our sociomoral ends consist in maximizing net felicity according to a calculus of public utility? In one sense, Hume provides no proof, at least not a proof that depends on adducing reasons; because, in a more important sense, there is no clearer proof than the elementary fact that we just do strive for happiness. As such, no appropriate reasons can be given for why it is pursued: “[If you] push your enquiries farther, and desire a reason, why he hates pain, it is impossible that he can ever give any. This is an ultimate end, which is never referred to any other object” (Hume, Reference Hume and Beauchamp1988, Appendix 1.18).

Such a minimalist conception of happiness as avoidance of pain is quintessentially Epicurean, and its elaboration by Lucretius contains a discussion of the injurious psychology of religious fear that complements Hume’s exposition of the agonizing paradox of belief in a just God who is bent on eternal damnation (Hume, Reference Hume and Gaskin1993b, 13.18, pp. 177–178; Lucretius, 1977, 2.20–2.61). Like Hume’s felicity, Epicurean felicity is grounded in an elementary fact about human nature for which further reasons cannot coherently be adduced. But there is a difference. The Epicurean analysis remains at that level of individual biopsychology, offering a negative felicity consisting in the avoidance of pain. By contrast, Hume situates that individual biopsychology in social conditions to explicate interpersonal moral psychology and the genesis of moral norms. Yet this difference is best understood as a contiguous extension of, rather than a departure from, Epicurus. Indeed, commensurate with Hume’s methodological aims in examining the foundations of ethics, it constitutes a (social) scientific refinement of Epicurean felicity. For the refinement does not alter the naturalist concept of felicity in the Epicurean account; it extends its scope from individual to collective psychology based on an equally naturalist understanding of humans as indelibly social animals, and therefore as capable of private felicity only in strict interdependence with the conditions of their mutual sociability.

This extension is pursued by Darwin, as is the resulting system of morals that, via Jeremy Bentham and Mill,Footnote ¹ traces back to Hume:

Insofar as net felicity — the greatest-happiness principle — denotes the end served by publicly utile means, Darwin’s reflection is prefigured all but verbatim by Hume: “Common interest and utility beget infallibly a standard of right and wrong among the parties concerned” (Hume, Reference Hume and Beauchamp1988, 4.20). This commonly discovered natural link between felicity as an inborn end and utility as the means that establishes the best pathways to attain it in a social environment also precludes attributing moral normativity to an arbitrary ground. As Hume urges:

As innate as psychological egoism or “self-love” (Hume, Reference Hume and Beauchamp1988, 5.16–5.17), Hume recognizes a socially wired inheritance in this “moral sentiment,” which he variously calls “natural philanthropy,” “sympathy,” and “humanity or fellow-feeling” (Hume, Reference Hume and Beauchamp1988, 5.17, 5.40, 2.5, 5.17 Footnote 3). Another term he uses is “benevolence,” without being naïve to the bountiful malevolence that also darkens the human heart: “there is some benevolence, however small, infused into our bosom; some spark of friendship for human kind; some particle of the dove, kneaded into our frame, along with the elements of the wolf and serpent” (Hume, Reference Hume and Beauchamp1988, 9.4).

Darwin echoes Hume in his recognition that the “development of the moral qualities […] lies in the social instincts” and in stressing that “the more important elements are love, and the distinct emotion of sympathy” (Darwin, 1871/Reference Darwin and Appleman2001b, p. 247). This sympathetic sentiment for agreement with utile tendencies extends the scope of felicity beyond individuality to the social orbit, and even to the species orbit. Since Darwin, this species-wide extension of sympathetic sentiment has been archeologically and genomically proven in Homo sapiens and Neanderthals through evidence of their caring for genetically unrelated injured and elderly individuals (see Reich, Reference Reich and Reich2019). For his part, Hume did not require such evidence of intra- and interspecies sympathy beyond that of his senses: “Animals are found susceptible of kindness, both to their own species and to ours […] Shall we account for all their sentiments too, from refined deductions of self-interest?” (Hume, Reference Hume and Beauchamp1988, Appendix 2.8).

But, while this sentimental core of morality is a necessary foundation of moral conduct, it is not sufficient for its ongoing development. As Darwin notes, a “moral being is one who is capable of reflecting on his past actions and their motives — of approving of some and disapproving of others,” and the “appreciation and the bestowal of praise and blame both rest on sympathy” (Darwin, 1871/Reference Darwin and Appleman2001b, p. 247). For Hume, it is also at this juncture that reflection — or reason — intercedes. Our natural kernel of moral sympathy is “so universal and comprehensive as to extend to all mankind” as the primordial sentimental monitor over actions and conduct, “according as they agree or disagree with that rule of right which is established” (Hume, Reference Hume and Beauchamp1988, 9.5). But this sentimental metric of actions is not an evaluative faculty. While sensitive to our inborn aversions to pain and preferences for happiness as beings limited by social conditions, for the ongoing judgement of the utility of the rules of right established in those conditions,

As judged by reason, the most utile tendencies to codify into rules of right are those that maximize net felicity. Nor does the failure of societies to enshrine such rules or minimize tendencies contrary to them undermine this prescription. Such failures are consistent with Hume’s moral naturalism, for they also stem from original sympathy and its societal horizon, except as maladaptive developments: “Popular sedition, party zeal, a devoted obedience to factious leaders; these are some of the most visible, though less laudable effects of this social sympathy in human nature” (Hume, Reference Hume and Beauchamp1988, 5.35).

One institution that reason judges collectively utile is justice, understood in its elementary sense as fairness and a proportional adjustment of crime to punishment. But Hume ridicules the notion that institutions of justice are innate ideas floated down from the superworldly Enclave of Mind: “Have we original, innate ideas of praetors, and chancellors and juries? Who sees not, that all these institutions arise merely from the necessities of human society?” (Hume, Reference Hume and Beauchamp1988, 3.43). Conspicuous in its absence is a purposive concept of justice guiding this enterprise, such as a final cause might do. Here lies another difference with his one-time mentor: While Hutcheson also grounds ethics in natural moral sense, Hume severs all ties with a telos that guides its evolution, limiting the ends of moral sense to human sociability and the institutions to which its demands give rise. Thus, even archetypal postulates of a future state and accountability to God are rendered unintelligible and unnecessary designs, due to the stark disanalogy of such concepts of justice with the convention of justice born out of our elementary psychological constitution and social evolution (cf. Russell, Reference Russell2008, p. 259).

Despite its artificial origin, this convention establishes elementary standards that are as universal as the moral sentiment on which its societal necessity is grounded:

Hume thus threads the needle between nature and artifice by anchoring the creation of moral codes and institutions in our passional and rational constitution. He summarizes that connection as follows: “If self-love, if benevolence be natural to man; if reason and forethought be also natural; then may the same epithet be applied to justice, order, fidelity, property, society” (Hume, Reference Hume and Beauchamp1988, Appendix 3.9). This fusion of nature and artifice is strikingly captured by Hume’s insistence on the natural necessity of rationally guided conventions: “In so sagacious an animal, what necessarily arises from the exertion of his intellectual faculties, may justly be esteemed natural” (Hume, Reference Hume and Beauchamp1988, Appendix 3.9). The genealogy of civilization described by Lucretius is premised on such an interplay between natural necessity and a rationally controlled development of anthropologically common conventions (Lucretius, 1977, 5.1143–5.1155, 5.1448–5.1457). Moreover, the natural rationality of such conventions implies that the establishment of norms that promote survival of the collective unit leverages an intelligence that is not exclusive to humans, but is shared with our ancient ancestors and animal kin.

Centuries after Hume, this point enjoys broad consensus among Darwinian theorists, philosophers, and scientists (see, e.g., Dennett, Reference Dennett1995, pp. 494–500; De Waal, Reference De Waal2013, pp. 149–188, 156–162, 223–240; Mayr, Reference Mayr2001, pp. 256–260; Ridley, 1997/Reference Ridley and Appleman2001). We can thus appreciate the interdisciplinary expansion of Humean-Darwinian naturalist ethics and its sidelining of God as enforcer, judge, or model of moral conduct. Against the conception of justice as an innate idea of reason from on high, developmental intuitions for fairness and distributive justice are widely recorded among human toddlers and infants, and their application to broader social norms extends beyond human evolutionary history to all hominids, many hominins, and even canids (see De Waal, Reference De Waal2013, pp. 149–188, 223–240). As Frans de Waal puts it, invoking terms that directly recall Hume’s and Darwin’s sociomoral accounts: “Evolution has produced the requisites for morality: a tendency to develop social norms and enforce them, the capacities of empathy and sympathy, mutual aid and a sense of fairness, the mechanisms of conflict resolution, and so on,” which have underpinned the development of primal modes of politics and culture among the higher apes (De Waal, 1996/Reference De Waal and Appleman2001, p. 513). Mayr argues that naturally selected altruistic traits, which are genetically inherited and directed at offspring, kin, and tribe, form the basis for society-wide morality out of culturally selected publicly utile conventions transmitted by “cultural learning” and “moral education” (Mayr, Reference Mayr2001, pp. 256–260). Darwin himself recognized that moral conventions were culturally selected and transmitted “through the effects of habit, example, instruction, and reflection” (Darwin, 1871/Reference Darwin and Appleman2001b, p. 248). And such appreciations of the nature-culture pipeline of moral evolution are consonant with Hume’s assertion that enculturation and reason extend our innate moral approbations and aversions “beyond their natural standard,” from kith and kin to wider society (Hume, Reference Hume and Beauchamp1988, 5.3). In all cases, the role of a God-given rationality enabling access to higher moral principles or a God-inspired manual inscribing such principles is rendered unnecessary, and even, as we will see, corrupting.

Hume is associated with the naturalistic fallacy — so-called Hume’s guillotine — which regards it impossible to derive an ‘ought’ from an ‘is’ or values from facts. Superficially, this flies in the face of his account of ethical foundations, which seems to do precisely that. Yet Hume’s anthropology of morals shows that, far from positing an absolute dichotomy, Hume promotes a symbiotic understanding of artificial ‘oughts’ and a natural ‘is’; what he rejects is the claim that sociomoral ‘oughts’ logically derive from a natural ‘is’ (Hume, Reference Hume and Mossner1969, 3.1.1, p. 521). This does not negate that ‘oughts’ are fundamentally responsive to a natural ‘is’ in the development of moral normativity. But it does deny the origin of morals in pure reason, instead establishing their genesis out of and in service to our naturally pre-existing needs and cares as social beings. This transition from a natural evolutionary ‘is’ to artificially evolved ‘oughts’ explains how common rules of justice across human communities arise and are to be expected: “The convenience, or rather necessity, which leads to justice, is so universal, and every where points so much to the same rules, that the habit takes place in all societies” (Hume, Reference Hume and Beauchamp1988, 3.47).

The non-arbitrary basis of such rules of justice is what grounds their normative force, while our natural ethical reasoning evaluates the utility of those rules insofar as they promote conditions that maximize net felicity. Thus, out of elementary sentiments of fairness and distributive justice, common rules are framed by a rational test of compatibility between individual felicity drives and social co-existence. To capture it in provocative yet warranted terms, this codification of rules depends on universalizing individual maxims of action to test their coherence in inter-agential contexts. It thus expresses the essence of Immanuel Kant’s categorical imperative, only stripped of its rationalist deontological scaffolding and couched in evolutionary naturalist terms. The warrant for this suggestion is Hume’s articulation of the types of questions for testing the possibility of universalizing maxims of action, much in the manner of Kant’s imperative; except that they do so, not in the service of transcendental logic, but of the continued practical possibility of society: “What must become of the world, if such practices prevail? How could society subsist under such disorders?” (Hume, Reference Hume and Beauchamp1988, 3.47).

That these questions for fielding maxims of action can be thus articulated should not be mistaken for a suggestion that they enter the mind as propositional states. The propositional state, assuming one takes place at all, is a subsequent and supplemental development of primal inductive reasoning and association of ideas, which are not exclusively human possessions. This critical consideration foregrounds Hume’s anti-intellectualism, which is one flank of his broader naturalist commitments to recasting differences between human and non-human animal intelligence as matters of degree, not kind (Hume, Reference Hume and Buckle2007a, 9.5). Darwin shares this perspective, devoting an entire chapter in Descent to the proposition that “there is no fundamental difference between man and the higher mammals in their mental faculties” (Darwin, 1871/Reference Darwin and Appleman2001b, p. 214). There, Darwin argues that the association of ideas is an act of reason performed by human and non-human beings, all the way down to the lowly pike, “whether or not any general proposition on the subject is consciously placed before the mind” (Darwin, 1871/Reference Darwin and Appleman2001b, p. 220). In effect, Darwin concludes through experimental observation what Hume finds through empirical reflection — namely, that the cultivation of habits of action that yield publicly utile outcomes requires intelligence as a developed faculty beyond inherited instinct: “It is a significant fact, that the more the habits of any particular animal are studied by a naturalist, the more he attributes to reason and the less to unlearnt instincts” (Darwin, 1871/Reference Darwin and Appleman2001b, p. 219).

With these mirroring naturalizations of reason in view, we find that Hume’s questions for measuring the public utility of maxims of action are linguistic and conceptual expressions of the pre-linguistic and pre-conceptual intelligent essence that drives the evolution of morality. That intelligent essence is explained by our natural evolutionary history, which has placed us in a matrix of agents with potentially conflicting personal needs and motives. Such conditions breed selective pressures on habits of action that are utile to the survival and net felicity of that social matrix over time, beyond the narrower scope of individual survival and felicity at single times. Our situation has thus necessitated a perspective that extends beyond the present and the individual to encompass the actions of others, along with the effects of those actions, within the social units from which our nature has become indissociable. And our rational faculty is the tool that performs the evaluative selection of publicly utile conventions that serve net felicity. Those publicly utile conventions are expressed as common rules, the compliance with which acquires a normative force that is bound up with the continued possibility of social stability.

In another extension of this account since Hume and Darwin, such complex inter-agential grids of actions have been modelled by decision theory, which even quantifies its variables in probabilistic theorems and formulae. To synthesize a discussion on this topic by Darwinian philosopher, Daniel Dennett, decision theory frames differential evolutionary success and strategies by holistically comprehending the selective pressures on phenotypes based on traits and habits of cohabitant species of a niche and the “decisions” these motivate vis-à-vis each other (Dennett, Reference Dennett1995, pp. 251–261). With a narrower focus on rational players, the foundations of ethics, as Hume and Darwin disclose them, show that the development of our morality has been driven by selective pressures that necessitate an intelligence capable of adjudicating decisions within the inter-agential social state, which our natural evolution has put us in. In this regard, socially utile felicity has been the sole foundation and end of moral reasoning; in that regard, too, religion has not. Indeed, as Epicurus accused centuries ago, religion has done nothing but corrupt our moral psychology and human happiness.

5. Irreligious Morality

Among the scandals caused by Hume’s Treatise, which contains the book that is expansively reprised in An Enquiry Concerning the Principles of Morals, was its “sapping the foundations of morality” — meaning the religious foundations — by basing it on “human conventions and compacts,” which undermine the divine provenance and absolute modality of moral categories (Hume, Reference Hume and Buckle2007b, p. 154). Darwin’s own anticipated reaction to Descent was that it would be “denounced by some as highly irreligious,” as it indeed was (Darwin, 1871/Reference Darwin and Appleman2001b, p. 249). Neither assessment of their works is misplaced. The systems of morality advanced by Hume and Darwin — prepossessed with an Epicurean anthropology that posits felicity as an inborn end, and endorsed as the most consistent with our evolutionary history and natural constitution — are signal rejections of traditional religious accounts of moral ends and means. At their core, they refute the utility of religious constructs for promoting the sociomoral conditions that best maximize net felicity. At their extreme, they condemn religion as inimical to felicity and the sociomoral norms that promote it.

While the emergence of religion has natural causes for Hume and Darwin, both have distinct problems with the emergence of religions that follow the popular theistic conception of God. Darwin rejects the idea that the belief in a beneficent God is natural, even while recognizing that belief in “spiritual agencies seems to be universal” (Darwin, 1871/Reference Darwin and Appleman2001b, p. 248). Nor is such a belief natural for Hume, even if its contingent historical emergence can be explained as a phase in the natural history of religion (Hume, Reference Hume and Gaskin1993b, 6–8, pp. 153–160). But, regardless of whether such a conception of God evolved naturally, its rise after the comprehensive establishment of morality out of purely natural means and needs, which are intelligently channelled into normative conventions, effectively severs morality from religion. Consequently, any pretensions to fuse religiosity and upright moral conduct fall apart. As Hume says in the Natural History: “it is justly regarded as unsafe to draw any certain inference in favour of a man’s morals, from the fervour or strictness of his religious exercises” (Hume, Reference Hume and Gaskin1993b, 14.7, p. 182). Instead, because morality pre-exists God and his contingent moral precepts, it follows that we are naturally self-sufficient moral agents. Armed with this same realization, Darwin untethers moral conscience from religion by relocating the former to the realm of natural moral intelligence. Rather than a prod for moral obedience fuelled by guilt and fear before God, conscience is an inductive instrument honed by education and self-reflection for schematizing possibilities to “act differently for the future” when individual passions and social instincts come into conflict (Darwin, 1871/Reference Darwin and Appleman2001b, pp. 247–248). This conflict would be appropriately gauged by the exact questions that Hume poses as litmus tests for the public utility of maxims of action.

Because we are, pre-religiously, self-sufficient moral agents, religious morality becomes an entity beyond the necessity of public utility. As in their assaults on intelligent design, and following the Epicurean lead, Occam’s Razor is commissioned against the postulation of God in the practical realm as well. As Hume argues in a chapter of Natural History unceremoniously titled “Bad Influence of Popular Religions on Morality”:

The shift from needless affectation to corrosive influence occurs the moment obedience to God’s moral system trounces our natural proclivities to follow publicly utile conventions that serve net felicity. At that point, religious morality blinds devotees from the naturalist realization that “the most genuine method of serving the divinity is by promoting the happiness of his creatures,” instead instilling fabricated needs that “offer the strongest violence to [their] natural inclinations” by fuelling a search for “more immediate service of the supreme Being, in order to allay those terrors, with which [they are] haunted” (Hume, Reference Hume and Gaskin1993b, 14.6, p. 181). The result is that public utility is sidelined by the unnatural and inculcated — yet now more pressing — need to serve God before serving society. And while religious moralities exist aplenty, Hume’s bête noire is the system of morals beholden to the traditional God of Abrahamic monotheisms, as is evident from the following calculus of lopsided morality: “The more tremendous the divinity is represented,” the more it becomes habit to defer to ministers of religious morals rather than to administrate our natural moral reasoning, and similarly, “the more unaccountable the measures of acceptance required by [God], the more necessary does it become to abandon our natural reason, and yield to their ghostly guidance and direction” (Hume, Reference Hume and Gaskin1993b, 14.8, p. 183).

The problem of religious morality is thus most urgently one of moral psychology under the popular theistic God. Interconnected reflections in Hume’s Natural History, Dialogues, Enquiry Concerning the Principles of Morals, and his essay on immortality elucidate this point. In Morals, he reminds us of the Epicurean essence of natural virtue: “her sole purpose is, to make her votaries and all mankind, during every instant of their existence, if possible, cheerful and happy” (Hume, Reference Hume and Beauchamp1988, 9.15). But this natural service to human felicity is twisted by religious morality into infelicitous service to a greater supernatural being: “Celibacy, fasting, penance, mortification, self-denial, humility, silence, solitude, and the whole train of monkish virtues […] neither advance a man’s fortune in the world, nor render him a more valuable member of society” (Hume, Reference Hume and Beauchamp1988, 9.3). This-worldly felicity renders those means for attaining religious virtue personally unsalutary and collectively undesirable, while rendering the end for which they are prescribed — other-worldly salvation — needless at best and corrupting at worst. That it proves corrupting indeed owes to the very concept of an afterlife and its necessary presupposition, the immortal soul. Together, these provide the foundations for the popular theistic model of moral obedience, in which death is no longer understood as a natural terminus but is transmogrified into the assurance of a permanent state after natural life to which infinite reward and punishment accrue based on this-worldly behaviour.

The identification of the effects of such anti-natural conceptions has Epicurean roots, as does the proposed solution: “This fright, this night of the mind must be dispelled/ not by the rays of the sun, nor day’s bright spears,/ but by the face of nature and her laws” (Lucretius, 1977, 3.91–3.93). The face of nature and her laws speak against an immortal soul and the immateriality it presupposes; to the contrary, it is plain that the soul is not an embodied thing but is of the body, as its mind: “mind and soul are joined/ together, and form one single entity, […] soul and mind are physical things” (Lucretius, 1977, 3.136–3.162). The soul qua mind is material and, consequently, mortal: “all the substance of the soul/ dissolves like smoke into the tall fleet air;/ for body and soul, we see, are linked in birth,/ in growth, and in the weary waste of years” (Lucretius, 1977, 3.455–3.458). In his eponymous essay on the immorality of the soul, Hume naturalizes the human soul back into the material mortality characteristic of every other animal soul, in clear tribute to these reflections from De Rerum Natura (Hume, Reference Hume and Buckle2007c, pp. 194–197). And Darwin’s anticipation of the scandal that Descent would cause stemmed specifically from its expected impact on the doctrine of immortality (Darwin, 1871/Reference Darwin and Appleman2001b, p. 249). For Darwin, once the natural evolution of social instincts and moral intelligence are disclosed, human beings cease to appear as ontological exceptions of the animal order, which means their souls cease to be exceptions as well. In effect, Darwin scientifically decommissions the immortal soul as an empirically tenable proposition, and with it, the religious system that hinges upon it as a practically needful one for moral intelligence and conduct.

While that irreligious fallout is implied by Darwin’s work, Hume makes it overt, having ditched the gloves by the point in his intellectual career in which he pens the immortality essay. There and in Dialogues — both published posthumously, with much trepidation by the executors of his will — Hume unleashes damning broadsides on the presumed beneficence of a God who models moral categories on the afterlife of an immortal soul. In Immortality, Hume reminds us of the naturally derived standards of fairness and distributive justice that govern moral normativity, noting that they are grotesquely violated by the very concept of divine justice:

The omnibenevolence of the God who expedites such punishment is laid waste, not by citing the traditional problem of evil, but by invoking God’s express model of moral obedience. By emplacing a future state of eternal punishment and reward to be meted out for finite actions upon an immortal soul, God cannot be good according to our natural moral conceptions, and is, in fact, damnable according to them. What is more, the very postulation of an afterlife of “infinitely greater consequence,” good or bad, when our inborn concerns are with present life, is described as an “injustice in nature […] Ought this barbarous deceit to be ascribed to a beneficent and wise being?” (Hume, Reference Hume and Buckle2007c, p. 192). But the injustice is not by nature; it is an injustice of God upon our natural orientation to life and justice.

The co-terminous doctrines of immortality and afterlife justify maxims of action that directly subvert natural moral proclivities, which could otherwise be properly cultivated in publicly utile ways to maximize net felicity. As Philo puts it in the final chapter of Dialogues, where the discussion turns from metaphysics and epistemology to morality:

Hume is not naïve to the fact that there are natural grounds for selfishness; but these, as argued in Morals, are either blameless in cases in which they are compatible with general social utility or, if contrary to it, express maladaptive developments of our social dispositions out of envy or revenge (Hume, Reference Hume and Beauchamp1988, 5.16–5.43). Yet even the latter can be curbed by common rules designed to protect net felicity against the clash of natural selfishness with social sympathy (Hume, Reference Hume and Beauchamp1988, 5.16–5.43). That such rules do not always succeed at that task is indisputable, but this does not refute the practical value of a yardstick of public utility for maximizing net felicity. Without it, publicly utile conventions and the rules they recommend could not be established in the first place, or if established, could not be rationally corrected to meet evolving cultural circumstances.

The religious moral yardstick of salvation based on doctrines of immortality and afterlife does not reflect a maladaptive development of social instincts. It stands as a categorical erasure of the social sentiments that drive rational vetting of publicly utile maxims of action and the corresponding sociolegal norms that tend to the maximization of net felicity. Even altruism becomes tainted with a false veneer of religiosity as the fundamental cause behind it, when nature alone has disposed such socially guided tendencies. Religions like laying exclusive claim to the Golden Rule; but such rules of right are observed universally, not because we adhere to a particular religion, but because our humanity adheres to natural reason. And yet, the natural end that such rules serve is obscured by religion’s promise of an anti-natural one, a world after nature. And that world — after mortal life, society, history, and the possibility of ongoingly redressing their discontents through human intelligence and sympathy — becomes the sole reason for which this world has utility at all.

6. Conclusion: Unseeing God in Nature

The works of Hume, Darwin, and Lucretius are not premised on atheism. They lead to a position like it, yet even more unsettling to religious inclinations than the simple denial of God. For they present a view of the world that demands that we increasingly, and then altogether, unsee God as a creative force in nature or guiding model for conduct. They call upon us to unsee God as an explanation of design, not just on grounds of being unnecessary, but of saddling our understanding with a Procrustean bed that our explanatory accounts must then contrive to fit through dubious epistemic acrobatics, the likes of which Philo unmasks in Cleanthes’s proposals in Dialogues and Darwin in those of spontaneous creationists in Origin. And they compel us to unsee God as a custodian of moral conduct in society on grounds of being an extraneous variable in the calculus of public utility that maximizes net felicity, and even on grounds of corrupting our natural motives to follow the norms that best promote that end.

After invoking the third man argument against Platonist cosmology, Philo illustrates this exercise in unseeing God by insisting upon a naturalistic departure to our thought that seemingly yields a theistic conclusion: “It were better, therefore, never to look beyond the present material world. By supposing it to contain the principle of its order within itself, we really assert it to be God” (Hume, Reference Hume and Gaskin1993a, 4.10, pp. 63–64). But the theistic assertion instantly proves threadbare, an empty rider tacked on to a self-sufficient system: “I fain would know, why it is not as good sense to say, that the parts of the material world fall into order, of themselves, and by their own nature?” (Hume, Reference Hume and Gaskin1993a, 4.10, p. 64). Similarly, as Epicurus claims and Hume’s Epicurean mouthpiece in the Enquiry Concerning Human Understanding reprises, to depart from nature and infer God on its basis is to affirm a principle “both uncertain and useless. It is uncertain, because the subject lies entirely beyond the reach of human experience. It is useless, because our knowledge of this cause being derived entirely from the course of nature” implies that God is at most and at best synonymous with nature, at which point it becomes a redundant add-on that cannot “establish any new principles of conduct and behaviour” beyond those that, by our nature, we evolve (Hume, Reference Hume and Buckle2007a, 11.23). This is not atheism, for God is yet permitted to exist; and yet, accepting God’s existence under such conditions means accepting an existence that is as unnecessary and as it is inconsequential. Atheism, the denial of God’s existence, seems a more attractive proposal to such godlessness indeed.

To unsee God in nature is to see the natural world in the full glory of its chances and contingencies, out of which emerge design and a reframed vision of our place within the cosmos. That place is decidedly humble, yet humble against the background of a mosaicked marvel of continuously emerging designs of life out of self-propelled natural evolution. Though hedged with characteristic scepticism, Philo confesses adherence to a vision much like this: “And were I obliged to defend any particular system of nature […] I esteem none more plausible than that which ascribes an eternal, inherent principle of order to the world; though attended with great and continual revolutions and alterations” (Hume, Reference Hume and Gaskin1993a, 6.12, p. 76). Darwin sees majesty in such a godless vision of the world and our renewed humility within it, as the coda of Origin famously proclaims: “There is grandeur in this view of life […] from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved” (Darwin, 1859/Reference Darwin and Appleman2001a, p. 174). He had not known that his irreligious, world-affirming clarion call to naturalistic awe revived the exact words of Lucretius upon expounding the naturalist system developed by his master, Epicurus: “Here stands a world revealed in all its grandeur” (Lucretius, 1977, 5.7). This perennial system of naturalism, first disclosed by Epicurus and refined by Hume and Darwin, thus fastens to the proposition that the world is, as it is, complete enough, designed enough, empowered enough — enough, simply — to have no need for God, or us for him.