In the section on evolutionary debunking arguments, you state morality is an adaptation, and later suggest that “The intuition that morality is objective (‘speaker-independent’) is a part of this adaptation.”
I believe you could present a clearer explanation of what you mean by (1) the claim that morality is an adaptation and (b) the intuition that morality is objective. Depending on what you mean, both claims may not be supported by the evidence.
(1) Moral cognition may not have evolved
With respect to the claim that morality evolved, Mallon & Machery (2010) provide at least three interpretations of what this could mean:
(a) Some components of moral psychology evolved
(b) normative cognition evolved
(c) moral cognition, “understood as a special sort of cognition” (p. 4), evolved.
They provide what strikes me as a fairly persuasive case that (a) is uncontroversially true, (b) is probably true, but (c) isn’t well-supported by available data.
Only (c) would easily support EDAs, while (b) may not and whether (a) could support EDAs would presumably depend on the details.
In subsequent papers, Machery (2018) and Stich (2018) have developed on this and related criticisms, arguing that morality is a culturally-contingent phenomenon and that there is no principled distinction between moral and nonmoral norms, respectively (see also Sinnott-Armstrong & Wheatley, 2012).
Given that you don’t take EDAs to be decisive, and given that (a) above may be sufficient to support relevant forms of EDAs, these concerns may not present much of an obstacle to your overall argument for antirealism, but I wanted to ensure you were aware that EDAs may be based on empirical claims that have yet to be uncontroversially established by available data.
(2) People may not be intuitive objectivists
A growing number of studies have attempted to evaluate the metaethical stances of nonphilosophers (e.g. Beebe & Sackris, 2016, Beebe et al., 2015; Collier-Spruel et al., 2019; Goodwin & Darley, 2008; Nichols, 2004; Wright, Grandjean, & McWhite, 2013; Yilmaz & Bahçekapili, 2015; Zijlstra, 2019).
Across a range of different paradigms and ways of asking, researchers have found evidence of both interpersonal and intrapersonal variation in metaethical stances: there are stable differences between participants in the degree to which they regard morality as objective, and there is variation in metaethical stance for individual participants with respect to different moral issues, such that some are treated as objective and others are not, with some findings indicating people often endorse non-cognitivism (Davis, forthcoming).
In other words, some people tend to be “more objectivist” and others tend to be “more relativist” overall regarding different moral issues. Yet at the same time, most people will treat some moral issues (e.g. murder) as “objective” and others (e.g. abortion) as “relative.”
Although there are significant methodological problems with this research (Bush & Moss, 2020; Pölzler, 2018), overall there is not strong evidence of a species-typical tendency to regard moral norms as uniformly objective.
There is a bit of cross cultural research on this (see Beebe et al., 2015) but nothing very impressive or compelling. It is possible that people evolved to treat morality as objective but that WEIRD populations exhibit an unusual tendency towards non-objectivist views of morality., or more generally, it could be that we are predisposed towards objectivism but this can be culturally overridden.
It’s also possible that these studies are reliably failing to measure metaethical beliefs accurately.
Even so, what evidence we do have does not vindicate the assumption that ordinary people are objectivists. In fact, some researchers working on the topic believe folk nonobjectivism makes better sense of the data (see Beebe, forthcoming).
References
Beebe, J.R. (forthcoming). The empirical case for folk indexical moral relativism. In Oxford studies in experimental philosophy (vol. 4).
Beebe, J.R., Sackris D. (2016). Moral objectivism across the lifespan. Philosophical Psychology 29 (6): 912–929.
Beebe, J.R., Qiaoan R., Wysocki T. et al. (2015) Moral objectivism in cross-cultural perspective. Journal of Cognition and Culture, 15(3–4): 386–401.
Bush L.S., & Moss. D., (2020). Misunderstanding metaethics: Difficulties measuring folk objectivism and relativism. Diametros, 1-16. https://doi.org/10.33392/diam.1495
Collier‐Spruel, L., Hawkins, A., Jayawickreme, E., Fleeson, W., & Furr, R. M. (2019). Relativism or tolerance? Defining, assessing, connecting, and distinguishing two moral personality features with prominent roles in modern societies. Journal of personality, 87(6), 1170-1188.
Davis, T. (forthcoming). Beyond objectivism: New methods for studying metaethical intuitions. Philosophical Psychology.
Goodwin, G. P., & Darley, J. M. (2008). The psychology of meta-ethics: Exploring objectivism. Cognition, 106(3), 1339-1366.
Machery, E. (2018). A Historical Invention. In K. Gray & J. Graham (Eds.), Atlas of Moral Psychology (pp. 259-265). Guilford Press.
Machery, E., & Mallon, R. (2010). Evolution of morality. In J. M. Doris et al. (Eds.), The moral psychology handbook (pp. 3–47). New York, NY: Oxford University Press.
Nichols, S. (2004). After objectivity: An empirical study of moral judgment. Philosophical Psychology, 17(1), 3-26.
Pölzler, T. (2018). How to measure moral realism. Review of philosophy and psychology, 9(3), 647-670.
Sinnott-Armstrong, W., & Wheatley, T. (2012). The disunity of morality and why it matters to philosophy. The Monist, 95(3), 355-377.
Stich, S. (2018). The moral domain. In K. Gray & J. Graham (Eds.), Atlas of Moral Psychology (pp. 547-555). Guilford Press.
Wright, J. C., Grandjean, P. T., & McWhite, C. B. (2013). The meta-ethical grounding of our moral beliefs: Evidence for meta-ethical pluralism. Philosophical Psychology, 26(3), 336-361.
Yilmaz, O., & Bahçekapili, H. G. (2015). Without God, everything is permitted? The reciprocal influence of religious and meta-ethical beliefs. Journal of Experimental Social Psychology, 58, 95-100.
Zijlstra, L. (2019). Folk moral objectivism and its measurement. Journal of Experimental Social Psychology, 84, 103807.
That would be one of the worries. If (c) distinctly moral cognition evolved, EDAs apply straightforwardly. If (b) normative cognition evolved, then there’d be a serious worry that they apply to normative cognition in general, and then you’d need to bring in the sorts of reasons you address in the footnote. If (a) processes involved in moral cognition evolved, then similar worries to (b) may arise insofar as the psychological systems involved in moral cognition are also involved in relevant nonmoral domains (e.g. epistemic norms).
What complicates matters if (a) is true and (c) is not is that we cannot present a uniform debunking argument against distinctively moral cognition by simply noting that moral cognition evolved; we’d have to look at the distinct evolutionary history of each of the processes involved in moral cognition.
Note, for instance, that if it is not the case that we have an evolved tendency to regard moral facts as distinctively objective, then EDAs that turn on this hypothesis will be based on a mistaken presupposition about the etiology of realist intuitions.
That is, you could be incorrect about the empirical facts when you agree with Ruse that “our intuitions in favor of moral realism evolved for reasons that have no connection to whether the position is true,” simply because it could be untrue that our intuitions in favor of moral realism evolved.
In short, if moral judgments are the output of more general systems for reasoning, prediction etc., it’s unclear if or how EDAs would apply to these systems. For instance, it may be that realist intuitions are not an output of a dedicated psychological process, instead, a result of general inferential processes that are not as straightforwardly subject to the concerns raised by standard EDAs.
FitzPatrick (2015) has raised some objections to EDAs that could readily draw on the status of empirical facts surrounding the evolution of morality. FitzPatrick claims that:
“[...] we don’t need natural selection to have given us cognitive capacities designed specifically to track a certain class of truths, on the model of perceptual adaptations, in order to be in a position now to track those truths non-accidentally and reliably, and to be warranted in our beliefs. Nor do we even need natural selection to have given us, as an incidental by-product of some unrelated adaptation, a ready-made, specialized capacity that happens to be attuned to the truths in question. Such a thing would indeed be as unlikely as natural selection’s coughing up the human eye as a fluke by-product of some unrelated adaptation. But again we don’t need any such thing. It’s enough if natural selection has given us general cognitive capacities that we can now develop and deploy in rich cultural contexts, with training in relevant methodologies, so as to arrive at justified and accurate beliefs in that domain.” (pp. 886-887)
The points raised here are less of a problem for the normative antirealist. But they do raise concerns about the specific etiology of our intuitions about moral realism and any other kind of realism. At the very least, I’d caution against the presumption that a given tendency to think about morality in a certain way has a distinctive evolutionary origin: you cannot dismiss realist intuitions on the grounds that they evolved if they didn’t evolve.
Inadequate consideration of the details of the evolution of normative and moral thought could misleadingly appear to close the door on some moves that are available to the moral antirealist. For instance, the evolutionary details will matter for anyone who wants to maintain skepticism about moral realism while still endorsing realism about other domains (e.g. epistemic norms). My colleagues and I discuss some of these possibilities in Millhouse et al. (2016), though I can’t speak for my coauthors and my comments here may conflict with what they think.
References
FitzPatrick, W. J. (2015). Debunking evolutionary debunking of ethical realism. Philosophical Studies, 172(4), 883-904.
Millhouse, T., Bush, L. S., & Moss, D. (2016). The containment problem and the evolutionary debunking of morality. In T. K. Shackelford & R. D. Hansen (Eds.), The evolution of morality (pp. 113-135). Springer, Cham.