Fact-checked by Grok 2 weeks ago

Evolutionary ethics

Evolutionary ethics is a naturalistic approach to moral philosophy that explains the origins of moral traits and behaviors as products of biological evolution, particularly through natural selection conferring selective advantages in social contexts.^[1] Emerging in the 19th century following Charles Darwin's On the Origin of Species, the field gained prominence with Darwin's own arguments in The Descent of Man (1871), where he proposed that the human moral sense evolved from social instincts, sympathy, and habit, enabling group cohesion and individual fitness.^[2] Key concepts include the evolutionary explanation of altruism via kin selection—where aiding genetic relatives enhances inclusive fitness—and reciprocal altruism, which fosters cooperation through mutual benefits over time.^[1]^[3] A major controversy surrounds the naturalistic fallacy, the philosophical objection that ethical prescriptions cannot be logically derived from empirical facts about evolutionary processes, though proponents argue that understanding moral psychology's adaptive roots informs ethical deliberation without committing this error.^[4] Despite debates over its prescriptive implications, evolutionary ethics has advanced descriptive accounts of morality, integrating empirical data from evolutionary biology and psychology to reveal how innate moral intuitions likely arose to solve recurrent adaptive problems in ancestral environments.^[1]

Historical Development

Nineteenth-Century Foundations

Charles Darwin laid foundational arguments for evolutionary ethics in The Descent of Man, and Selection in Relation to Sex (1871), positing that the human moral sense originated from social instincts evolved among group-living ancestors through natural selection.^[5] He observed altruistic behaviors in animals, such as bees sacrificing for the hive and wolves aiding injured pack members, as precursors to human morality, arguing that these instincts, combined with memory and approbation from the group, foster conscience. Darwin contended that any social animal with sufficient intellectual capacity would develop a moral sense, as natural selection favors cooperation enhancing group survival over individual selfishness.^[5] Herbert Spencer extended evolutionary principles to ethics in his multi-volume The Principles of Ethics (1879–1893), integrating "survival of the fittest"—a phrase he coined in 1864—to describe moral progress. Spencer viewed natural selection as driving societies from militant egoism toward industrial altruism, where sympathy and mutual aid increase fitness in complex civilizations.^[6] He argued that ethical norms emerge empirically from evolutionary adaptations, with justice and beneficence arising as maladaptation to egoistic impulses decreases under selection pressures. In contrast, Thomas Henry Huxley critiqued direct derivations of ethics from evolution in his Romanes Lecture, "Evolution and Ethics" (1893), emphasizing a sharp divide between naturalistic processes and human morality.^[7] Huxley described cosmic evolution as a relentless, amoral struggle marked by predation and waste, akin to a "cosmic process" of unchecked competition, which humans must counteract through deliberate ethical restraint rather than embrace.^[7] He advocated for cultivated reason and social institutions to impose checks on evolved instincts, viewing ethics as a human artifact opposing nature's cruelty, not an extension of it.^[7]

Early Twentieth-Century Decline

In 1903, G.E. Moore published Principia Ethica, introducing the concept of the naturalistic fallacy, which critiqued attempts to define ethical terms like "good" in purely natural or empirical terms, such as those derived from evolutionary processes.^[8] Moore argued that equating "good" with properties like evolutionary fitness or adaptation—prevalent in Herbert Spencer's evolutionary ethics—commits a definitional error, as "good" is a simple, non-natural, indefinable property ascertainable only through intuition, not reducible to descriptive facts about survival or reproduction.^[9] This open-question argument posited that even if something is identified as evolutionarily advantageous, questioning whether it is truly good remains meaningful, undermining claims that biological evolution directly yields moral truths.^[4] Moore's analysis revived and amplified David Hume's earlier is-ought distinction from A Treatise of Human Nature (1739-1740), which highlighted the logical gap between descriptive statements about what is (e.g., evolved human behaviors) and prescriptive statements about what ought to be (e.g., moral obligations).^[10] Early 20th-century philosophers, influenced by Moore, invoked Hume to argue that evolutionary facts could explain the origins of moral sentiments or practices but could not bridge the inferential divide to normative ethics without additional, non-empirical premises.^[11] This reinforced skepticism toward biologized ethics, portraying attempts to derive ethical imperatives from Darwinian mechanisms as invalid non sequiturs. The critiques contributed to a philosophical retreat from evolutionary approaches, evident in figures like Henry Sidgwick, whose Methods of Ethics (1874, with later editions) engaged evolutionary insights into moral psychology but ultimately prioritized philosophical intuitionism over biological reductionism to resolve ethical conflicts.^[12] Sidgwick grappled with evolutionary explanations for altruism and utilitarianism but deemed them insufficient for ultimate justification, favoring self-evident axioms discerned intuitively.^[13] Concurrently, the rise of logical positivism in the 1920s and 1930s, associated with the Vienna Circle, further marginalized normative evolutionary ethics by classifying moral statements as neither empirically verifiable nor analytically true, thus cognitively insignificant and unworthy of scientific or philosophical biologization.^[14] This intellectual shift stalled development in the field until later revivals, prioritizing linguistic analysis and emotivism over causal accounts rooted in natural selection.

Late Twentieth-Century Resurgence

In the 1970s, evolutionary ethics experienced a revival through the emergence of sociobiology, which applied empirical findings from ethology, population genetics, and behavioral ecology to explain the biological underpinnings of social behaviors, including those foundational to human morality. This shift emphasized descriptive mechanisms over speculative normative derivations, drawing on mathematical models of natural selection to account for phenomena like altruism without invoking supernatural or purely cultural explanations. Key to this was the integration of William D. Hamilton's 1964 kin selection theory, which posits that behaviors favoring genetic relatives enhance inclusive fitness, providing a non-intuitive basis for apparent self-sacrifice.^[15] A pivotal contribution came from Robert Trivers' 1971 formulation of reciprocal altruism, which theorized that costly aid to non-kin could evolve if recipients return favors in future interactions, stabilized by mechanisms like memory, reputation, and punishment for cheaters. This model, published in the Quarterly Review of Biology, predicted stable cooperation under conditions of repeated encounters and low dispersal, and it received empirical support from primate studies, such as grooming alliances in vervet monkeys (Chlorocebus pygerythrus) where individuals exchanged support contingent on prior reciprocity, as documented in long-term field observations. Trivers' framework extended kin selection by addressing cooperation among unrelated individuals, influencing subsequent research on moral reciprocity in humans and animals without prescribing ethical oughts.^[16] Edward O. Wilson's Sociobiology: The New Synthesis (1975) synthesized over 2,000 references from animal behavior studies to argue that human moral faculties, including emotions like guilt and empathy, represent extensions of adaptive social strategies shaped by kin selection, reciprocal altruism, and emerging debates over group selection. Wilson contended that these traits evolved to maximize inclusive fitness in ancestral environments, with human ethics as a culturally elaborated overlay on innate predispositions, evidenced by cross-species parallels in eusocial insects and vertebrates. The book's final chapter controversially applied these ideas to humans, sparking interdisciplinary debate but grounding claims in quantitative models like Hamilton's rule (rB > C, where r is relatedness, B benefit to recipient, and C cost to actor).^[15] Complementing Wilson, Richard Dawkins' The Selfish Gene (1976) popularized a gene-centered perspective, asserting that natural selection acts primarily on replicators—genes—rather than organisms, rendering seemingly ethical behaviors like parental investment or heroism as vehicles for gene propagation. Dawkins explained altruism via "greenbeard" effects and extended phenotypes, where genes promote traits benefiting copies in other bodies, as in haplodiploid systems yielding eusociality in hymenopterans; this view reframed moral intuitions as byproducts of gene-level competition, supported by simulations showing stable strategies in iterated prisoner's dilemma games analogous to reciprocal exchanges. The work's emphasis on empirical falsifiability and avoidance of teleology bolstered descriptive evolutionary ethics against earlier anthropocentric interpretations.^[17] These developments rehabilitated evolutionary approaches by prioritizing testable hypotheses and data from field biology, such as vampire bat blood-sharing (reciprocal feeding observed in 12% of non-kin interactions) and primate coalitions, fostering a resurgence that bridged biology and ethics through causal explanations of behavior rather than philosophical deduction. Group selection models, critiqued by Dawkins but revisited in multilevel selection frameworks, added nuance to debates on cultural evolution's role in moral systems.^[18]

Descriptive Evolutionary Ethics

Biological Origins of Moral Behaviors

Moral behaviors in humans and other social animals arise from adaptive responses shaped by natural selection to enhance survival and reproductive success in interdependent groups. Traits such as empathy, reciprocity, and aversion to exploitation promote inclusive fitness by facilitating cooperation among kin and non-kin, reducing the costs of conflict, and deterring free-riders. These behaviors manifest as intuitive judgments—e.g., preferring to aid relatives or punishing norm violators—without requiring cultural transmission alone; instead, they stem from heritable cognitive and emotional mechanisms honed over millennia in ancestral environments where group living conferred advantages.^[19] Kin selection provides a foundational mechanism, where altruism evolves preferentially toward genetic relatives to propagate shared genes. W.D. Hamilton's 1964 rule states that a gene for altruism will spread if the benefit to the recipient (B), weighted by genetic relatedness (r), exceeds the cost to the actor (C): rB > C; this quantitatively predicts nepotistic behaviors like parental investment and sibling favoritism observed across species, including humans' stronger emotional bonds and resource allocation to closer kin. Empirical support includes genetic studies of eusocial insects and human twin data showing heritable variation in familial altruism, underscoring how such traits maximize indirect fitness gains in viscous populations with limited dispersal.^[20]^[21] Beyond kin, reciprocal altruism extends cooperation to unrelated individuals through iterated interactions, as modeled by Robert Trivers in 1971: costly aid is repaid in future encounters, with natural selection favoring mechanisms for partner choice, memory of past exchanges, and cheater detection to stabilize mutualism. In humans, this underpins fairness norms, evidenced by evolutionary psychology experiments revealing specialized cognitive adaptations; for instance, Cosmides and Tooby's work demonstrates that people excel at identifying social contract violators (cheaters) in logical tasks mimicking exchange rules, performing far better than on neutral problems, indicating domain-specific modules evolved for reciprocity enforcement.^[22]^[19] Cross-cultural universals in moral prohibitions, such as incest taboos against mating with close relatives, trace to inclusive fitness maximization by averting inbreeding depression, which increases homozygosity and genetic disorders. Anthropological surveys of over 100 hunter-gatherer societies reveal near-universal prohibitions on parent-child and sibling unions, corroborated by the Westermarck effect—where co-reared individuals develop sexual aversion—and genetic models estimating 20-50% fitness costs from close inbreeding. These patterns persist independently of kinship terminology or residence rules, suggesting innate psychological adaptations rather than purely learned conventions, with violations eliciting visceral disgust akin to pathogen avoidance.^[23]^[24]

Empirical Evidence and Key Studies

Twin studies in behavioral genetics have demonstrated moderate heritability for prosocial traits, including empathy and altruism. Analyses of adolescent twins estimate the heritability of prosocial behavior at 30-50%, with shared environmental influences playing a lesser role. ^[25] Adult twin studies report broader heritabilities of 56-72% for self-reported measures of altruism, empathy, and nurturance, indicating substantial genetic contributions alongside unique environmental factors. ^[26] Neuroimaging research provides evidence of neural mechanisms underlying fairness judgments, consistent with evolved social preferences. In functional magnetic resonance imaging (fMRI) experiments using the ultimatum game, participants rejected unfair monetary offers despite personal cost, accompanied by heightened activation in the anterior insula—a region associated with negative emotional responses such as disgust—compared to fair offers. ^[27] This activation pattern suggests an innate aversion to inequity, potentially shaped by selection for cooperative interactions in ancestral groups. Observational and experimental studies in non-human animals reveal precursors to moral behaviors through reciprocity and punishment-like responses. Vampire bats (Desmodus rotundus) engage in reciprocal food sharing by regurgitating blood to unsuccessful roost-mates, with donation rates correlating independently with kinship and prior reciprocation opportunities, even among non-kin in captivity. ^[28] In chimpanzees (Pan troglodytes), third-party interventions occur in approximately 8% of observed freeloading events during cooperative tasks, where dominant individuals target non-cooperators, indicating emergent enforcement of group norms beyond direct self-interest. ^[29] Experimental paradigms, however, show limited evidence of disinterested third-party punishment, as chimpanzees rarely incur costs to penalize violations of others' cooperation. ^[30]

Normative Evolutionary Ethics

Attempts to Derive Ethical Norms from Evolution

Herbert Spencer sought to derive ethical norms from evolutionary principles by asserting that moral progress consists in the increasing dominance of altruism over egoism as societies evolve toward greater complexity and mutual dependence. In works such as Data of Ethics (1879) and Principles of Ethics (1892–1893), Spencer maintained that natural selection in the "superorganic" domain of human society favors cooperative behaviors, rendering altruism not merely adaptive but morally superior, as it aligns with the cosmic tendency toward equilibrium and harmony.^[31] This framework intuitively appealed by portraying ethics as an extension of biological success, though it presupposed that evolutionary fitness equates to moral value without bridging the gap from descriptive adaptation to prescriptive obligation.^[32] In the late twentieth century, philosopher Peter Singer adapted evolutionary insights to bolster utilitarian norms, arguing that the genetically rooted capacity for sympathy—initially biased toward kin and reciprocators—can be rationally expanded to impartial concern for all sentient beings, thereby maximizing aggregate welfare in a manner analogous to inclusive fitness extended globally. In The Expanding Circle: Ethics and Sociobiology (1981), Singer posited that this "expanding circle" of moral consideration, driven by reason overriding evolved parochialism, justifies utilitarian prescriptions against speciesism and for effective altruism, as broader impartiality promotes long-term evolutionary and societal flourishing.^[33] Such derivations hold intuitive force by linking biological imperatives to ethical universality, yet rely on interpretive leaps from kin selection's mechanics to deontological-like duties. Proponents of multilevel selection, including Elliott Sober and David Sloan Wilson, have proposed that ethical norms emerge from traits selected at both individual and group levels, where behaviors sacrificing personal fitness for collective benefit—such as parochial altruism favoring in-groups—enhance group survival and thus warrant prescriptive endorsement. In Unto Others: The Evolution and Psychology of Unselfish Behavior (1998), they defended group selection as a viable mechanism for evolving moral sentiments, suggesting that norms promoting intergroup competition alongside intragroup cooperation reflect adaptive realities, potentially justifying ethical systems that prioritize communal solidarity over universal benevolence. This approach intuitively rationalizes observed moral intuitions like loyalty and patriotism as evolutionarily honed virtues, but invites derivation of norms from contingent group dynamics rather than invariant principles.^[34]

Achievements in Explaining Altruism and Cooperation

Kin selection theory, formalized by W. D. Hamilton in 1964, resolves the evolutionary puzzle of altruism by demonstrating that self-sacrificial behaviors can spread genetically when the indirect fitness benefits to relatives exceed the actor's costs, encapsulated in Hamilton's rule rB > C, where r denotes genetic relatedness, B the benefit to the recipient, and C the cost to the actor.^[20] ^[21] This framework causally explains apparent self-sacrifice in contexts where direct reproduction is forgone, such as sterile workers in eusocial insect colonies, where haplodiploid sex determination elevates average relatedness to 0.75 among sisters, favoring altruism toward siblings over personal reproduction; empirical studies across Hymenoptera species, including ants and bees, confirm that colony-level cooperation aligns with inclusive fitness predictions under varying relatedness levels.^[35] In humans, kin selection accounts for nepotistic biases observed in resource allocation and parental investment, with experimental and cross-cultural data showing stronger altruism toward closer genetic relatives, consistent with rB > C thresholds in decisions like organ donation or inheritance preferences. Reciprocal altruism extends explanations beyond kin ties, as shown in Robert Axelrod's 1981 computer tournaments of the iterated Prisoner's Dilemma, where the tit-for-tat strategy—starting with cooperation and subsequently mirroring the opponent's prior action—outperformed alternatives by fostering mutual benefit in repeated interactions, even among non-relatives. This approach elucidates the evolution of cooperation in social groups by highlighting how reciprocity enforces conditional altruism, punishing defection while rewarding collaboration; simulations revealed tit-for-tat's robustness due to its "nice, retaliatory, forgiving, and clear" properties, providing a mechanistic basis for moral norms like trustworthiness and retaliation in human societies, with real-world analogs in sustained alliances observed in economic games and historical conflicts. Costly signaling theory, via Amotz Zahavi's 1975 handicap principle, further illuminates moral altruism as an honest advertisement of fitness, where extravagant acts (e.g., self-denial or generosity) impose verifiable costs that only high-quality individuals can bear, thereby signaling underlying traits like health or resource-holding potential to build trust and cooperative coalitions. ^[36] In evolutionary ethics, this explains virtue displays as adaptive signals rather than pure self-sacrifice, with empirical support from studies linking unconditional altruism to enhanced perceptions of donor intelligence and status, as costly prosociality correlates with cognitive ability and predicts mating or alliance success; agent-based models demonstrate how such signals stabilize partial cooperation in groups by deterring cheaters through the sustainability costs of deception.^[37] ^[38]

Criticisms of Normative Approaches

The Naturalistic Fallacy and Is-Ought Problem

David Hume articulated the is-ought problem, also known as Hume's guillotine, in A Treatise of Human Nature (1739–1740), observing that moral arguments often illicitly transition from descriptive claims about what is the case—such as empirical facts about human behavior or natural processes—to prescriptive claims about what ought to be without justifying the leap through additional normative premises.^[39] In the context of evolutionary ethics, this manifests when attempts are made to derive ethical imperatives directly from evolutionary biology's descriptive accounts of trait selection; for instance, the fact that natural selection favored certain cooperative behaviors in ancestral environments (is) does not logically entail that such behaviors ought to be pursued today, as no inherent normative force bridges the gap.^[40] G. E. Moore formalized the related naturalistic fallacy in Principia Ethica (1903), arguing against equating ethical concepts like "good" with any natural property, including those posited by evolutionary theory such as adaptive fitness or survival value.^[41] Moore's open-question argument underscores this: if "good" were truly identical to "evolutionarily adaptive," then questioning whether something adaptive is good would be incoherent, yet such questions remain meaningfully open, revealing that evolutionary definitions fail to capture the non-natural, intrinsic nature of ethical value.^[39] Proponents of normative evolutionary ethics who assert that moral obligations stem from evolved preferences or genetic predispositions thus commit this fallacy by reducing oughts to contingent biological descriptions, overlooking that origins explain causal history without prescribing universal validity.^[40] Even granting empirical details of evolutionary processes—such as kin selection promoting altruism in social species—these facts remain irrelevant to justification, as adaptive traits in Pleistocene-like environments may prove maladaptive in contemporary settings altered by technology and global interdependence, further severing any prescriptive inference.^[41] This logical severance persists regardless of the strength of descriptive evidence, as first-principles analysis confirms that causal explanations of moral sentiments' emergence cannot substitute for independent normative evaluation, rendering evolutionary ethics vulnerable at its foundational attempt to ground oughts in is-statements.^[39]

Risks of Justifying Harmful Behaviors

Normative evolutionary ethics, by positing that moral obligations derive from traits enhancing reproductive fitness, has historically rationalized eugenic policies aimed at curtailing reproduction among those deemed genetically inferior. Francis Galton, in his 1883 book Inquiries into Human Faculty and Its Development, coined the term "eugenics" and advocated selective breeding to improve human stock, explicitly invoking Darwinian natural selection to prioritize population-level fitness over individual autonomy.^[42]^[43] This framework influenced early 20th-century laws, such as those in the United States where, from 1907 onward, over 60,000 forced sterilizations targeted the poor, disabled, and minorities under the rationale of preventing hereditary "degeneration" and maximizing societal genetic quality.^[44] Although these measures were scientifically invalidated by advances in genetics revealing complex trait inheritance and environmentally influenced outcomes, the causal chain from evolutionary fitness maximization to coercive interventions highlights how misapplied normative derivations can endorse harm by framing it as biologically imperative.^[45] Evolutionary accounts of morality also risk justifying in-group biases and aggression by portraying them as adaptive mechanisms honed in ancestral coalitional conflicts. Research in evolutionary psychology indicates that xenophobia and intergroup hostility likely evolved to protect against threats like resource competition or pathogen transmission in small-scale tribal societies, where out-group encounters posed survival risks.^[46]^[47] A normative extension might then prescribe favoring kin or co-ethnics in resource allocation—such as discriminatory hiring or territorial defense—as ethically sound if they boost inclusive fitness, clashing with impartial ethical systems that prohibit harm based on arbitrary group boundaries. Empirical studies, including those on the "male warrior hypothesis," show heightened aggression toward out-groups in males, correlating with historical warfare patterns, yet applying this descriptively evolved tendency prescriptively ignores modern contexts where such behaviors exacerbate social fragmentation without corresponding fitness gains.^[46] Furthermore, evolutionary ethics' emphasis on context-dependent adaptations fosters relativism, eroding firm barriers against harms like conquest or entrenched inequality when recast as extensions of competitive dynamics. Morals shaped by kin selection and reciprocal altruism in Pleistocene bands prioritize local reciprocity over universal equity, enabling rationalizations of exploitation—such as imperial expansions or caste-like hierarchies—if they secure differential reproductive success for dominant coalitions.^[31] This undermines absolute ethical constraints, as varying ecological pressures across history produced divergent norms (e.g., honor cultures endorsing vendettas for status preservation), allowing post-hoc defenses of inequality as "natural" outcomes of variance in heritable traits rather than addressable through institutional reforms.^[31] Causal analysis reveals these as contingent products of selection pressures, not timeless imperatives, yet prescriptive uses overlook how scaled-up societies alter payoff matrices, rendering ancestral heuristics maladaptive and ethically hazardous without supplemental normative checks.^[31]

Evolutionary Metaethics

Debunking Arguments Against Moral Realism

One prominent evolutionary challenge to moral realism arises from Sharon Street's "Darwinian Dilemma," articulated in her 2006 paper. Street argues that natural selection favors beliefs and dispositions that enhance reproductive fitness rather than those that accurately track objective moral truths. Under moral realism, normative properties exist independently and our moral intuitions purportedly evolved to detect them; however, the causal history of these intuitions—shaped by survival pressures over millions of years—renders it improbable that they reliably correspond to such truths unless moral facts causally influence fitness in a non-question-begging manner, which Street contends is implausible given the contingency of evolutionary outcomes.^[48]^[49] Thus, moral realism faces a trilemma: deny the evolutionary explanation of moral beliefs (contradicting empirical evidence), accept that evolution undermines tracking reliability (defeating realism), or posit an improbable alignment between moral truths and fitness benefits. Richard Joyce extends this genealogical critique in his 2006 book The Evolution of Morality and subsequent work, positing that the adaptive origins of moral judgments erode their epistemic warrant for realists. Joyce maintains that moral beliefs, such as intuitions about wrongness or obligation, emerged as byproducts of selection processes aimed at behavioral regulation for social cooperation, not truth-apt representation of mind-independent facts. This non-veritistic etiology implies that even if moral realism were true, our moral faculties lack the reliability needed for justified belief, akin to an error theory where apparent moral knowledge dissolves into adaptive illusion.^[50] For instance, Joyce highlights how moral nativism—evidenced by cross-cultural patterns in infant morality studies—supports innateness but ties it to fitness-tracking mechanisms, not accuracy about objective values.^[51] Empirical underpinnings of these arguments draw on findings that moral beliefs correlate more strongly with fitness proxies than with putative truth. Studies on parochial altruism, such as those showing enhanced cooperation toward in-groups via oxytocin-modulated biases, suggest moral intuitions prioritize kin and tribal survival over universalist norms, challenging realist claims of detecting impartial truths. Without independent vindication—beyond evolutionary history—realism falters, as the selection process would equally produce false positives for morality if they aided propagation, mirroring perceptual illusions adapted for quick environmental navigation rather than veridicality. These critiques thus shift the burden to realists to demonstrate how moral epistemology escapes Darwinian skepticism.^[52]

Responses Defending Objective Morality

Moral realists respond to evolutionary debunking arguments by proposing third-factor explanations that account for the correlation between adaptive moral beliefs and objective moral truths without undermining reliability. David Enoch contends that evolution selects for beliefs tracking survival and reproductive success, and if such outcomes possess independent moral value—as realists posit—then this shared factor explains why many moral intuitions approximate truth, akin to how perceptual beliefs track fitness-relevant facts without being debunked.^[52] This approach avoids circularity by grounding the explanation in realist premises that survival's goodness causally links evolutionary pressures to veridical beliefs, preserving epistemology against selective skepticism.^[53] Realists further argue that debunking overlooks potential causal roles for moral facts in evolution. Objective wrongs or rights, if causally efficacious, could motivate fitness-enhancing behaviors—such as cooperative restraint from harm—precisely because beliefs accurately reflect them, rendering evolution compatible with truth-tracking rather than antithetical.^[54] This indirect influence implies that non-tracking beliefs would underperform adaptively, as misaligned motivations yield poorer outcomes in social environments where moral coordination confers advantages, thus selecting against error systematically.^[55] Empirically, defenses emphasize that debunking arguments overreach by assuming evolution operates in isolation from truth-conducive mechanisms. Moral cognition exhibits domain-general reflective capacities, including error-detection and cross-cultural convergence on core prohibitions like gratuitous harm, which exceed parochial adaptations and align with Bayesian-like updating toward reliable inferences, countering claims of inherent unreliability.^[52] Such features suggest evolution leverages general-purpose cognition for moral domains, where success correlates with approximating objective constraints rather than fabricating illusions, as evidenced by persistent moral progress in reducing practices like infanticide across societies.^[56] These responses collectively affirm moral realism's resilience, positing evolution as a selector favoring, not undermining, access to moral facts.

Broader Implications and Debates

Herbert Spencer popularized the phrase "survival of the fittest" in his 1864 work Principles of Biology, applying Darwinian natural selection to human societies to argue that competitive struggles among individuals and nations drive progress.^[57] This selectionist logic empirically linked societal outcomes to differential reproductive success and resource acquisition, as observed in biological evolution, but Spencer's normative extension justified laissez-faire capitalism—opposing welfare or regulation as interfering with the elimination of the unfit—and imperialism, portraying colonial expansion as the triumph of superior groups over weaker ones.^[58]^[59] Such applications, while grounded in causal mechanisms of variation and selection, erred in deriving prescriptive ethics from descriptive processes, ignoring how human cooperation and cultural factors often override raw fitness maximization. In the early 20th century, eugenics movements in the United States drew on similar evolutionary rationales to advocate selective breeding for societal "improvement," positing that human intervention could accelerate natural selection by curbing reproduction among those deemed genetically inferior.^[60] By 1927, over 30 states had enacted sterilization laws, culminating in the Supreme Court's Buck v. Bell decision, which upheld the forced sterilization of Carrie Buck under Virginia law, with Justice Oliver Wendell Holmes Jr. invoking evolutionary logic: "Three generations of imbeciles are enough."^[60]^[61] This ruling facilitated approximately 70,000 sterilizations nationwide by mid-century, justified by pseudoscientific claims of heritable traits like feeblemindedness, yet later empirical advances in genetics revealed the oversimplification of complex polygenic inheritance and environmental influences, undermining the policies' foundational assumptions.^[62]^[61] Contemporary transhumanism echoes these connections by promoting technological and genetic enhancements to boost human fitness, framing such interventions as a moral extension of evolutionary progress to overcome biological limits.^[63] Advocates argue that tools like CRISPR gene editing or cognitive augmentation align with selectionist principles by favoring traits that enhance survival and reproduction in modern environments, potentially outpacing natural variation.^[64] However, this perspective underscores evolution's amoral core—prioritizing replicator propagation without inherent value judgments—contrasting with narratives that romanticize enhancement as inevitable ethical advancement, as causal analysis shows enhancements may disrupt co-evolved traits without guaranteed net fitness gains.^[65]

Compatibility with Theistic and Secular Realisms

Evolutionary ethics aligns with theistic realism by positing that natural selection operates within a teleological framework ordained by divine purpose, wherein moral intuitions emerge as reliable guides to objective goods inherent in human nature. Thomistic philosophers argue that evolution does not preclude inherent directedness toward ends, as biological processes reflect final causes embedded in creation, allowing moral norms to function as proximate rules derived from ultimate divine law.^[66] This view reconciles Darwinian mechanisms with Aquinas's natural law theory, interpreting adaptive traits like altruism not as products of blind chance but as expressions of providential design that promote flourishing aligned with eternal verities.^[67] In this integration, theistic evolutionists maintain that God's sustenance of natural laws ensures selection pressures favor moral capacities attuned to transcendent realities, countering materialist reductions that deny purpose. For instance, the universality of inclinations toward self-preservation, kin care, and reciprocal justice—observable in human behavior across epochs—mirrors Aquinas's hierarchy of natural appetites, suggesting evolution instantiates rather than originates ethical order. Empirical patterns in cooperative behaviors, conserved through selective retention, thus serve as evidence of designed teleology rather than stochastic accident.^[68] Secular realists defend compatibility by contending that evolutionary processes can track mind-independent moral truths, as adaptations conferring survival advantages correlate with objective values like harm minimization and mutual benefit. Russ Shafer-Landau argues that while evolution explains the etiology of moral beliefs, it does not entail their falsity; instead, natural selection likely preserves faculties disposed toward veridical moral perception, akin to how it refines perceptual reliability for empirical facts.^[69] This "discovery" model posits evolution as a mechanism for approximating ethical realism, where fitness-enhancing traits align with non-natural properties of rightness and wrongness independent of human endorsement.^[70] Cross-cultural empirical data bolster this realist stance, revealing near-universal prohibitions against gratuitous harm and imperatives for cooperation, which undermine claims of morality as mere cultural artifact. Studies across 60 societies identify consistent rules—such as aiding kin, reciprocating favors, and respecting property—as solutions to recurrent social dilemmas, with violations eliciting condemnation regardless of local variation.^[71] These convergences, rooted in adaptive necessities, indicate an objective core to ethics, resistant to relativistic interpretations that prioritize subjective constructs over such invariant patterns.^[72]

References

[1]
20th WCP: Evolutionary Ethics and Biologically Supportable Morality
The term 'evolutionary ethics' denotes an approach to naturalistic moral philosophy which seeks to explain how moral traits and behavior evolved.
[2]
Moral Nature - Darwin Correspondence Project |
In Descent of Man, Darwin argued that human morality had evolved from the social instincts of animals, especially the bonds of sympathy and love.
[3]
Kin selection and altruism - ScienceDirect.com
Jun 3, 2019 · For a long time, kin selection was primarily used to understand the evolution of altruism in vertebrates and insects, and that of eusocial ...Missing: ethics | Show results with:ethics
[4]
On the Naturalistic Fallacy: A Conceptual Basis for Evolutionary Ethics
The Naturalistic Fallacy is deriving values from facts or 'ought' from 'is', prohibiting value statements from purely factual statements.
[5]
the descent of man and selection in relation to sex - Project Gutenberg
Dec 27, 2021 · The moral sense—Fundamental proposition—The qualities of social animals—Origin of sociability—Struggle between opposed instincts—Man a social ...
[6]
Herbert Spencer, The Principles of Ethics. Two Volumes in One (1897)
Jan 9, 2021 · Survival of the fittest insures that the faculties of every species of creature tend to adapt themselves to its mode of life. It must be so ...
[7]
[PDF] Evolution and ethics, and other essays
BRAME, JR. HERPETOLOGICAL LIBRARY. Page 4. Page 5. COLLECTED ESSAYS. By T. H. HUXLEY. VOLUME IX. Page 6. Page 7. EVOLUTION & ETHICS. AND OTHER ESSAYS. THOMAS H.
[8]
Moore's Moral Philosophy
Jan 26, 2005 · G.E. Moore's Principia Ethica of 1903 is often considered a revolutionary work that set a new agenda for 20th-century ethics.
[9]
PRINCIPIA ETHICA (1903) by G. E. Moore - Fair Use Repository
Three possible views as to the relation of Evolution to Ethics are distinguished from the naturalistic view to which it is proposed to confine the name ...
[10]
Western ethics from the beginning of the 20th century - Britannica
... Hume's remark about writers who move from “is” to “ought.” Moore, however, would have considered Hume's own account of morality to be naturalistic, because ...
[11]
Hume on Is and Ought | Issue 83 | Philosophy Now
Hume's idea seems to be that you cannot deduce moral conclusions, featuring moral words such as 'ought', from non-moral premises, that is premises from which ...
[12]
Henry Sidgwick - Stanford Encyclopedia of Philosophy
Oct 5, 2004 · The ascent to this philosophical intuitionism is especially evident in the treatment of common-sense or intuitional morality. As Sidgwick ...The Methods Of Ethics And... · Economics, Politics, Education · Bibliography
[13]
Sidgwick's Ethics - Cambridge University Press & Assessment
Feb 24, 2025 · Section 2 discusses Sidgwick's approach to moral justification – intuitionism – which is central to his critical attack on common-sense morality ...
[14]
[PDF] Logical Positivism and the Demise of 'Moral Science'
Logical Positivism caused the demise of moral science by viewing moral theory as cognitively empty, treating its claims as nonsense, and as only a branch of ...
[15]
Sociobiology - Stanford Encyclopedia of Philosophy
Nov 11, 2013 · Wilson seems to intend “the biological basis of behavior” to refer to the social and ecological causes driving the evolution of behavior in ...1. Sociobiology As... · 2. ``pop Sociobiology'' · 3. Sociobiology As Human...
[16]
Reciprocal Altruism - an overview | ScienceDirect Topics
Trivers (1971) suggested that many of the human psychological ... In some primates that form multimale groups, males cooperate in intergroup aggression.
[17]
Selfish genetic elements and the gene's-eye view of evolution - PMC
In The Selfish Gene (Dawkins 1976), he argues that the gene level offers a uniquely correct representation of the causal processes underlying evolutionary ...
[18]
Sociobiology - an overview | ScienceDirect Topics
3 Sociobiology. Sociobiology is the systematic study of the biological basis of all social behavior in all organisms, including humans (Wilson 1975).Ethical Behavior, Evolution... · 3 Sociobiology · Scope And History Of...
[19]
Adaptive specializations, social exchange, and the evolution ... - PNAS
May 5, 2010 · The evolutionary function of a cheater detection subroutine is to defend the cooperator against exploitation. ... L Cosmides, J Tooby Moral ...
[20]
The genetical evolution of social behaviour. I - ScienceDirect.com
A genetical mathematical model is described which allows for interactions between relatives on one another's fitness.Missing: original | Show results with:original
[21]
Hamilton's rule and the causes of social evolution - PubMed Central
Hamilton's rule is a central theorem of inclusive fitness (kin selection) theory and predicts that social behaviour evolves under specific combinations of ...
[22]
The Evolution of Reciprocal Altruism | The Quarterly Review of Biology
The Evolution of Reciprocal Altruism. Robert L. Trivers. Robert L. Trivers ... Copyright 1971 Stony Brook Foundation, Inc. PDF download · Sign up for new ...Missing: original | Show results with:original
[23]
On the Origin and Extension of the Incest Taboo - Melvin Ember, 1975
The new evi dence has to do with why the incest taboo may be extended to first cousins; of all the available theories, only that of inbreeding seems to explain ...
[24]
The evolution and functional significance of incest avoidance
The human incest taboo is regarded as a cultural epiphenomenon following ... Genetics, ecology and the origins of incest and exogamy. Current ...
[25]
Behavioral genetic analyses of prosocial behavior in adolescents
Adult and child twin studies typically estimate the heritability of prosocial behavior to be between 30 and 50%, although relatively little is known about ...
[26]
Review Genetics of Human Social Behavior - ScienceDirect.com
Mar 25, 2010 · Broad heritabilities (56%–72%) were observed in adult twin pairs for self-reported measures of altruism, empathy, and nurturance, with only a ...
[27]
The neural basis of economic decision-making in the Ultimatum Game
We used functional magnetic resonance imaging of Ultimatum Game players to investigate neural substrates of cognitive and emotional processes involved in ...
[28]
Reciprocal food sharing in the vampire bat - Nature
Vampire bats share blood by regurgitation, depending on relatedness and opportunity for reciprocity, even with unrelated bats in captivity.
[29]
How chimpanzees cooperate in a competitive world - PNAS
Third-party punishment. Third-party outsiders intervened 14 times (8.0% of freeloading events), primarily responding to aggression between the freeloader and ...
[30]
No third-party punishment in chimpanzees - PNAS
The results suggest that chimpanzees do not punish third-party violations of cooperative behavior. Chimpanzees were as unlikely to collapse a table, causing ...
[31]
Morality and Evolutionary Biology
Dec 19, 2008 · Descriptive Evolutionary Ethics: appeals to evolutionary theory in the scientific explanation of the origins of certain human capacities, ...
[32]
[PDF] EVOLUTIONARY ETHICS: ITS ORIGINS AND CONTEMPORARY ...
The modern conception of evolutionary ethics had its inception in the period immediately following the publication of On the Origin of Species by Charles Darwin ...
[33]
https://press.princeton.edu/books/paperback/9780691150697/the-expanding-circle
[34]
Unto Others. The evolution and psychology of unselfish behavior
In Unto Others, we argue to the contrary, that group selection is a conceptually coherent and empirically well documented cause of evolution. We suggest, in ...
[35]
Kin selection and eusociality - Nature
Mar 23, 2011 · There is abundant evidence to demonstrate that inclusive fitness, kin selection and Hamilton's rule have been extraordinarily productive for understanding the ...
[36]
The Handicap Principle: how an erroneous hypothesis became a ...
Oct 23, 2019 · Zahavi (1975) originally proposed the Handicap Principle to explain signals that are costly and honest, but then argued that it explains all ...
[37]
Altruistic behavior as a costly signal of general intelligence
Based on costly signaling theory, we propose and show that unconditional altruistic behavior is related to general intelligence.
[38]
Evolution of costly signaling and partial cooperation - Nature
Jun 19, 2019 · We show that costly signals and costly cooperative strategies can co-evolve as a result of internal dynamics of the system.
[39]
The problem of the naturalist fallacy for evolutionary ethics
The naturalist fallacy is a problem in evolutionary ethics, where it's fallacious to define 'good' using natural properties, or to derive moral conclusions ...
[40]
20th WCP: Evolutionary Ethics: A Crack in the Foundation of Ethics?
According to Moore, attempts to render the moral term into natural, i.e. non-moral, terminology suffers from the 'naturalistic fallacy'.
[41]
Evolution and the Naturalistic Fallacy (Chapter 5)
Consequently, either the naturalistic fallacy is no fallacy, or no ethical system can be justified.
[42]
The Origins of Eugenics | Facing History & Ourselves
Aug 4, 2015 · Learn about Francis Galton and the beginnings of eugenics, or “race science,” and consider the relationship between science and society.
[43]
Eugenics: Its Origin and Development (1883 - Present)
Nov 30, 2021 · Eugenics is an immoral and pseudoscientific theory that claims it is possible to perfect people and groups through genetics and the scientific laws of ...
[44]
U.S. Scientists' Role in the Eugenics Movement (1907–1939) - NIH
The practice of forced sterilizations for the “unfit” was almost unanimously supported by eugenicists. The American Eugenics Society had hoped, in time, to ...
[45]
Eugenics and Scientific Racism
May 18, 2022 · Eugenics is the scientifically inaccurate theory that humans can be improved through selective breeding of populations. Eugenicists believed in ...
[46]
Evolution and the psychology of intergroup conflict: the male warrior ...
Evolutionary psychologists make the reasonable assumption that selection pressures operating in our evolutionary past may have shaped basic psychological ...
[47]
Pathogens and Immigrants: A Critical Appraisal of the Behavioral ...
Oct 25, 2019 · A body of literature in evolutionary psychology that seeks to attribute negative attitudes to ethnic and racial minorities and other outgroups to an evolved ...
[48]
A Darwinian Dilemma for Realist Theories of Value
A Darwinian Dilemma for Realist Theories of Value. Published: January 2006. Volume 127, pages 109–166, (2006); Cite this ...
[49]
A Darwinian dilemma for realist theories of value - PhilPapers
A Darwinian dilemma for realist theories of value · Sharon Street · Philosophical Studies 127 (1):109-166 (2006). @article{Street2006-STRADD, author = {Sharon ...
[50]
[PDF] The evolutionary debunking of morality Richard Joyce - PhilPapers
Moral nativism in the Darwinian context is the thesis that the capacity to make moral judgments is a human adaptation: The reason we classify the world in moral ...
[51]
The evolution of morality. - APA PsycNet
In The evolution of morality, Richard Joyce takes up these controversial questions, finding that the evidence supports an innate basis to human morality.
[52]
Evolutionary arguments against moral realism: Why the empirical ...
Nov 12, 2018 · The aim of this article is to identify the strongest evolutionary debunking argument (EDA) against moral realism and to assess on which empirical assumptions ...
[53]
When Do Replies to the Evolutionary Debunking Argument Against ...
Apr 18, 2018 · Some proponents of the evolutionary debunking argument against moral realism believe that replies that assume substantive moral claims beg the question.Missing: responses defending
[54]
[PDF] IN WHAT SENSE IS EVOLUTION BLIND TO MORAL TRUTH?
It assumes only that reflection about metaphysically impossible worlds can illuminate causal relationships, and this is both compatible with Moral.
[55]
8 - Evolution and the Epistemological Challenge to Moral Realism
The claim is only that evolution has been one powerful causal influence on the content of our moral judgments. To avoid confusion, I should note a few of ...
[56]
Evolutionary Debunking Arguments and the Reliability of Moral ...
Aug 9, 2025 · Debunking arguments use empirical evidence about our moral beliefs - in particular, about their causal origins, or about how they depend on ...
[57]
Social Darwinism in America: History for Kids ***
Herbert Spencer first coined the phrase "survival of the fittest" in his 1864 'Principles of Biology', after reading Charles Darwin's Origin of Species.
[58]
Social Darwinism - Encyclopedia of U.S. Political History
Spencer applied Darwin's ideas of natural selection to social phenomena such as population growth. In 1864, Spencer coined the phrase “survival of the fittest” ...
[59]
Social Darwinism: Definition & Theory | StudySmarter
Dec 2, 2022 · Those who believed in Social Darwinism wanted laissez-faire capitalism and believed in survival of the fittest. The theory embraced a socio ...
[60]
Buck v. Bell - Teaching American History
Supporters of eugenics and sterilization hoped the case would reach the Supreme Court and that the Court would find sterilization constitutional. This would at ...
[61]
The Supreme Court Ruling That Led To 70000 Forced Sterilizations
Mar 7, 2016 · In the first half of the 20th century, American eugenicists used forced sterilization to "breed out" traits they considered undesirable.
[62]
[PDF] Buck v. Bell, American Eugenics, and the Bad Man Test
Jan 5, 2020 · Abstract: With its 1927 decision in Buck v. Bell (“Buck”), the Supreme. Court embraced the American eugenics program, which was then.
[63]
Genetic enhancement from the perspective of transhumanism
Aug 28, 2024 · Transhumanism is a movement that advocates for the enhancement of human capabilities through the use of advanced technologies such as ...
[64]
On the (Non-)Rationality of Human Enhancement and Transhumanism
Nov 1, 2022 · The human enhancement debate has over the last few decades been concerned with ethical issues in methods for improving the physical, ...
[65]
[PDF] A New Evolutionary Perspective on Human Enhancement
In enhancement ethics, evolutionary theory has been largely perceived as supporting liberal views on enhancement, where decisions to enhance are.
[66]
Morality as a cause, not only an effect, of evolution: Thomistic ...
Feb 4, 2025 · This motivates Thomists to see morality as a natural phenomenon, in the sense that it emerges from, and remains premised on, the teleological ...
[67]
Thomistic Reflections on Teleology and Contemporary Biological ...
Jan 1, 2024 · Modern biologists often claim to be committed to a strong reductionist conception of scientific explanation, in contrast to the teleological explanations of ...
[68]
Aquinas, Darwin and Natural Law: Teleology and Immutability of ...
T. H. Huxley's essay and prolegomena of 1894 argued that the process and products of evolution are morally unacceptable and act in opposition to the ethical ...<|separator|>
[69]
Russ Shafer-Landau, Evolutionary Debunking, Moral Realism and ...
This paper reconstructs what I take to be the central evolutionary debunking argument that underlies recent critiques of moral realism.
[70]
Moral Realism and Evolutionary Debunking Arguments (Chapter 12)
If realists are entitled to assume that certain specific moral beliefs are true, then they need only explain how evolutionary pressures may have influenced us ...
[71]
Testing the Theory of Morality-as-Cooperation in 60 Societies
The theory of “morality-as-cooperation” argues that morality consists of a collection of biological and cultural solutions to the problems of cooperation.
[72]
[PDF] Seven Moral Rules Found All Around the World Oliver Scott Curry
We conclude that these seven cooperative behaviours are plausible candidates for universal moral rules, and that morality-as cooperation could provide the ...