Skip to main content

Debunking evolutionary debunking of ethical realism


What implications, if any, does evolutionary biology have for metaethics? Many believe that our evolutionary background supports a deflationary metaethics, providing a basis at least for debunking ethical realism. Some arguments for this conclusion appeal to claims about the etiology of the mental capacities we employ in ethical judgment, while others appeal to the etiology of the content of our moral beliefs. In both cases the debunkers’ claim is that the causal roles played by evolutionary factors raise deep epistemic problems for realism: if ethical truths are objective or independent of our evaluative attitudes, as realists maintain, then we lose our justification for our ethical beliefs once we become aware of the evolutionary shaping of our ethical capacities or beliefs, which would not have disposed us reliably to track independent ethical truths; realism, they claim, thus saddles us with ethical skepticism. I distinguish and spell out various evolutionary debunking arguments along these lines and argue that they all fail: the capacity etiology argument fails to raise any special or serious problem for realism, and the content etiology arguments all rely on strong explanatory claims about our moral beliefs that are simply not supported by the science unless it is supplemented by philosophical claims that just beg the question against realism from the start. While the various debunking arguments do bring out some interesting commitments of ethical realism, and even raise some good challenges as realists develop positive moral epistemologies, they fall far short of their debunking ambitions.

This is a preview of subscription content, access via your institution.


  1. For a very helpful reconstruction and critical examination of a variety of current evolutionary debunking arguments, see Shafer-Landau (2012).

  2. Talk of “design” here is metaphorical shorthand for the relevant selection-based account of the etiology of complex adaptive structures and functions, and “independent moral truths” means moral truths that are not functions of our evaluative attitudes (desires, approval, values, etc.) but have relevantly independent grounds.

  3. I spell this out more fully in FitzPatrick (2014).

  4. Street (2006, pp. 142–143) claims that the realist who grants that our ability to grasp independent moral truths is not an adaptation but (in part) a by-product of some adaptive capacities C are committed to thinking that a highly sophisticated and specialized capacity, specifically attuned to independent moral truths, would have to have arisen as a mere fluke by-product of an unrelated adaptation C. As argued in the text, this is not so: it is no more true in the case of morality than it is in the case of metaphysics, etc.

  5. We must also, of course, have enough freedom from any distorting evolutionary influences on our psychology that we can exercise our cognitive capacities in the way suggested above. This will be taken up in the discussion of Content Etiology arguments below, which addresses Street’s more central argument. Note that while I am in the present section criticizing one of her objections to realism (i.e., her argument that realists have no plausible story to tell about how we could have developed the ability to track independent moral truths despite its not being an adaptation), I’m not claiming that she herself endorses the Capacity Etiology Argument. In fact, given her own subjectivist constructivist view of evaluative truth and her rejection of moral skepticism, she cannot plausibly suppose that the only way for current exercises of evolved capacities to be non-accidentally and reliably truth-tracking in the moral domain would be for natural selection to have made things that way. For although her evaluative truths are constructions rooted in subjective states, these constructed truths were no more the concern of natural selection than the realist’s independent moral truths.

  6. Cf. Enoch (2010, p. 428): “Given a starting point of normative beliefs that are not too far-off, presumably some reasoning mechanisms (and perhaps some other mechanisms as well) can get us increasingly closer to the truth by eliminating inconsistencies, increasing overall coherence, eliminating arbitrary distinctions, drawing analogies, ruling out initially justified beliefs whose justificatory status has been defeated later, etc”.

  7. As Nagel (1986) has remarked, it’s not at all clear such a thing was inevitable or even likely.

  8. Cf. Street (2006, p. 124), Schafer (2010, p. 475).

  9. Note that by making the defeater turn not simply on 3 but on our awareness of 3, the argument clearly applies even to epistemic internalists. Cf. Bedke (2009). Also, although the conclusion is here put in terms of defeated justification for moral beliefs, one might also focus directly on the undermining of moral knowledge by the element of coincidence (regardless of what is said about justification): either way, the argument would show that moral realism leads to moral skepticism. It would thus be insufficient in responding to the argument simply to try to save justification without addressing the further problems for knowledge posed by coincidence here. See my critique of pure “third factor” approaches in FitzPatrick (2014).

  10. In fact, Joyce’s and Kitcher’s appeal to a complete non-moral genealogy for moral beliefs goes even further than the claim in the text above, since it is not restricted to denying a role for independent moral truths: their claim is that moral truths (independent or otherwise) play no role in the explanation of our moral beliefs—at least unless the moral truths in question are reducible to the sorts of facts that enter into the true causal explanations they posit. If they do not so reduce, then the more general version of the argument would equally pose a threat to antirealists such as Street who wish to preserve moral knowledge: for if her abstract, constructed moral truths are just as explanatorily marginalized with respect to our moral beliefs as the realist’s independent truths are, then she will face the same coincidence worry.

  11. This way of running the argument comes from Joyce (2006, Chap. 6), though as noted in the previous footnote, he goes even further, dropping the qualification ‘independent’ throughout. One assumption, of course, is that the moral truths posited by the targeted views are not reducible to facts involved in the ‘non-moral’ genealogy of our beliefs (e.g., facts about natural selection history). If they were, then the argument would not provide grounds for eliminating them from our ontology.

  12. Bedke (2009), for example, presses a version of the Implausibly Lucky Coincidence argument that appeals simply to causal determinism, physicalism about mental states, and causal closure of the physical, though it is limited specifically to targeting forms of intuitionistic non-naturalist realism that deny any causal efficacy for moral facts and properties.

  13. Cf. FitzPatrick (2008, 2011, 2014), for discussions of Street and Joyce related to the arguments that follow.

  14. Some defenders of realism, such as Enoch (2010, 2011) and Wielenberg (2010), have instead focused on resisting premises 2 or 4a; indeed, they may feel compelled to accept premise 1 by a version of ethical non-naturalism that insists that moral properties and facts are entirely causally inefficacious. I think this is a mistake, and that realism probably cannot be salvaged if premise 1 is granted. I argue against such pure “third factor” or “pre-established harmony” approaches to saving realism in FitzPatrick (2014). Fortunately, this isn’t a problem because as argued in this section, realists have no good reason to accept premise 1 to begin with.

  15. The same is true for theological concepts. Perhaps the concept of the divine is a bad one that should be discarded, but that cannot be shown just by arguing that it is an extension and refinement of a cruder concept that originally arose for purely evolutionary reasons. Someone who believes in God today based on an argument from cosmological fine tuning needn’t abandon that belief simply because he’s told that our ancient ancestors believed in gods for reasons having nothing to do with theological facts.

  16. I do not mean to imply that all good reasons for moral beliefs must be truth makers for those beliefs. Some moral knowledge may well be testimonial (e.g., I know that X is on balance wrong because Bob says it is and he is trustworthy about such things). But at least many of our moral beliefs had better be based on making-reasons, if we are to have the kind of knowledge the realist I’m defending thinks we have, and even cases of testimonial knowledge must trace back to something non-testimonial (e.g., Bob’s knowledge of the reasons why X is wrong).

  17. Of course, some cases may be mixed, involving some combination of the realist’s model (for what the agent got right on the way to the belief) and a debunking model (for what caused the belief to go wrong). Thanks to Andrew Greenlee for this point.

  18. As noted earlier, instead of putting the conclusion in terms of defeated justification, one might instead put it in terms of the undermining of moral knowledge by the element of coincidence involved, which equally supports the conclusion about realism leading to skepticism.

  19. Schafer (2010, pp. 474–475) correctly points out that it’s not enough, in answering Street’s arguments, simply to appeal to our current capacities for reflection and reasoning: for such higher-level moral cognition will not do much good if “the materials on which this reasoning and reflection operates” are so thoroughly saturated with evolutionary influence that they are largely off base to begin with. My point, however, is precisely that we are not saddled with this problem because we have no reason to grant Street such a strong claim about the evolutionary etiology of nearly all of our moral intuitions to begin with: many may instead spring from more recent encounters with value.

  20. It’s worth noting that even if realism is false and there aren’t any independent moral truths at all, there’s still little reason to accept 1*. An antirealist expressivist or an error theorist could just as plausibly hold that our judgments are still often the result of innovative redeployments of our (evolved) faculties rather than simply results of thinking along the ruts laid down for us by our evolutionary history. Indeed, given the degree of variation in moral judgment, we have every reason to believe that such innovation has been robust. Cf. Kahane (2011, p. 118).

  21. As already noted, we should actually expect a significant amount of incidental pushing of our evaluative tendencies in the right direction, given the social selection pressures on the psychologies of ancestral humans. This point, which Copp (2008) calls the “quasi-tracking thesis,” is not the primary response to Street’s dilemma on my view. But it’s an important secondary point to mitigate worries that whatever evolutionary influence there has been is debilitating. I discuss this and related points in FitzPatrick (2014).

  22. Cf. FitzPatrick (2008) and Kahane (2011, p. 118).

  23. Recall that the independence of moral facts and properties refers only to their not being functions of our evaluative attitudes, as on Street’s subjectivist constructivism. Realists need not claim that they are altogether independent of facts about human nature, such as our fundamental emotional potentialities.


  • Bedke, M. (2009). Intuitive non-naturalism meets cosmic coincidence. Pacific Philosophical Quarterly, 90, 188–209.

    Article  Google Scholar 

  • Copp, D. (2008). Darwinian skepticism about moral realism. Philosophical Issues, 18, 186–206.

    Article  Google Scholar 

  • Enoch, D. (2010). The epistemological challenge to metanormative realism: how best to understand it, and how to cope with it. Philosophical Studies, 148, 413–438.

    Article  Google Scholar 

  • Enoch, D. (2011). Taking morality seriously. Oxford: Oxford University Press.

    Book  Google Scholar 

  • FitzPatrick, W. (2008). Morality and evolutionary biology. In E. N. Zalta (Ed.), Stanford Encyclopedia of Philosophy. Retrieved, from

  • FitzPatrick, W. (2011). Biology, evolution and ethics. In C. Miller (Ed.), The continuum companion to ethics (pp. 275–290). London: Continuum.

    Google Scholar 

  • FitzPatrick, W. (2014). Why there is no Darwinian dilemma for ethical realism. In M. Bergmann, & P. Kain (Eds.), Challenges to moral and religious belief: Disagreement and evolution. Oxford: Oxford University Press.

  • Griffiths, P., & Wilkins, J. (In Press). When do evolutionary explanations of belief debunk belief? In P. Sloan (Ed.), Darwin in the 21st century: Nature, humanity, and God. Notre Dame, IN: Notre Dame University Press.

  • Haidt, J. (2001). The emotional dog and its rational tail: a social intuitionist approach to moral judgment. Psychological Review, 108, 814–834.

    Article  Google Scholar 

  • Joyce, R. (2006). The evolution of morality. Cambridge: MIT Press.

    Google Scholar 

  • Kahane, G. (2011). Evolutionary debunking arguments. Nous, 45, 103–125.

    Article  Google Scholar 

  • Kitcher, P. (2011). The ethical project. Cambridge, MA: Harvard University Press.

  • Nagel, T. (1986). The view from nowhere. New York: Oxford University Press.

    Google Scholar 

  • Railton, P. (2010). Moral camouflage or moral monkeys? In The New York Times, The Stone, July 18. Retrieved, from

  • Schafer, K. (2010). Evolution and normative skepticism. Australasian Journal of Philosophy, 88, 471–488.

    Article  Google Scholar 

  • Shafer-Landau, R. (2012). Evolutionary debunking, moral realism and moral knowledge. Journal of Ethics and Social Philosophy, 7, 1–37.

    Google Scholar 

  • Street, S. (2006). A Darwinian dilemma for realist theories of value. Philosophical Studies, 127, 109–166.

    Article  Google Scholar 

  • Street, S. (2008). Reply to Copp: Naturalism, normativity, and the varieties of realism worth worrying about. Philosophical Issues, 18, 207–228.

    Article  Google Scholar 

  • Wielenberg, E. (2010). On the evolutionary debunking of morality. Ethics, 120, 441–464.

    Article  Google Scholar 

Download references


I am grateful to Michael Bergmann, Selim Berker, Matthew Braddock, Earl Conee, Andrew Greenlee, Patrick Kain, Marc Lange, Karl Schafer, Nico Silins, Brad Weslake, and audiences at Princeton, Cornell, and the Eastern Division APA (2011), for helpful feedback on earlier drafts of this paper and related work.

Author information

Authors and Affiliations


Corresponding author

Correspondence to William J. FitzPatrick.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

FitzPatrick, W.J. Debunking evolutionary debunking of ethical realism. Philos Stud 172, 883–904 (2015).

Download citation

  • Published:

  • Issue Date:

  • DOI:


  • Natural Selection
  • Moral Judgment
  • Moral Belief
  • Moral Knowledge
  • Moral Fact