In the 1980s, Ruse wrote a series of important papers that revived evolutionary ethics. The debate on the implications of evolved moral intuitions for ethics remains very active up to today (see e.g., this conference that I'll be attending in a couple of hours, at least if the British railway system isn't disrupted by half an inch of snow!). Contemporary evolutionary ethics can build on a wealth of research, for instance, in the cognitive neuroscience of morality, developmental psychology, and the study of altruism in animals. But the metaethics of the folk remains a relatively understudied area. Are people intuitive moral realists? If so, what is the connection between metaethics and behavior?
Ruse hypothesized that humans are intuitive moral realists, and that this metaethical intuition has an evolved function: "human beings function better if they are deceived by their genes into thinking that there is a disinterested objective morality binding upon them, which all should obey" (Ruse & Wilson, 1986, 179). Ruse thought that if everyone thought that morality was subjective, that it was merely a matter of taste or convention, our social systems would collapse. Intuitive moral realism was thus a key component in human altruistic behavior, held together by moral beliefs, which in turn were cemented by intuitive moral realism. As Ruse wrote later on: "Substantive morality stays in place as an effective illusion because we think that it is no illusion but the real thing" (Ruse, 2010, 310).
When Ruse first formulated this hypothesis, it was by no means clear that humans were intuitive moral realists. Also, it was not clear to what extent an intuitive moral realism, if anything, helped us to act more morally. In the meantime, there is some empirical work on this, which I'll discuss briefly below the fold.
If moral realism is the dominant folk metaethical view, does this motivate us to act more in accordance with those norms than if we were moral subjectivists? This is an important building block of Ruse's theory, even though it by itself would not suffice to establish his view that moral realism is an illusion with the evolved function to hold morality in place. Nichols (2004) found that adults who responded like moral subjectivists (i.e., who argued that torturing puppies and hitting others is not objectively wrong) nevertheless thought that such moral norm violations are very serious; there were no systematic differences between objectivists and subjectivists in this survey. One explanation for this might be that although these students may have held the reflective belief that morality is subjective, they continue to hold on to their intuitive moral convictions (e.g., reflectively, they think that hitting others is not objectively wrong, but non-reflectively, they believe that it is).
In a recently published paper, Young and Durwin used a more implicit test to gauge the motivating force of moral realism. In one of the experiments, they set up an experimenter as a street-canvasser for a charitable organization. There was a neutral control condition, next to 2 conditions that primed moral realism and anti-realism, respectively. The realist prime was "Do you agree that some things are just morally right or wrong, good or bad, wherever you happen to be from in the world?" In the antirealism condition, the canvasser asked: "Do you agree that our morals and values are shaped by our culture and upbringing, so there are no absolute right answers to any moral questions?" While there was no difference between the neutral and antirealism condition, people primed with moral realism were twice as likely to donate to the charity compared to those in the other conditions.
Does this study support Ruse's view? The authors themselves offer explanations that seem to me more parsimonious, although they are not incompatible with Ruse's proposal (they would then be proximate mechanisms, whereas the ultimate explanation would be the evolutionary advantage of increased cooperation between humans). First, moral realism might render one's own moral status (and changes in that status) more salient, motivating people to take actions that help maintain or improve that status. Second, they suggest that priming moral realism may prime empathetic or collectivist attitudes, making people more connected with others (e.g., those who benefit from the charity). Whatever the results, I think it is premature to conclude from this that folk moral realism has an evolutionary origin, but it does suggest an interesting connection between metaethics and behavior.