In fact, the strong view of some evolutionary theorists—that real moral reasoning is impossible—isn’t even coherent. As an example, take Robert Kurzban’s excellent book, “Why everyone (else) is a hypocrite,” which argues that there is no unified self and that consciousness is largely superfluous—moral reasoning instead arises from a cluster of mental systems shaped by natural selection, leading to often inconsistent assessments of the behavior of others.

But then, at the very end of his book, Kurzban complains about what a mess this all is—“My own view is that while hypocrisy is the natural state of the human mind, it makes for bad policy.” He is particularly concerned by how unjust it is when people restrict the liberty of others without cause, as when our sexual morality makes us freak out at the behavior of consenting adults. He suggests that a better understanding of how the internal dynamics of the mind works, “gives us the opportunity to appreciate the conflict, and to change the balance of power.”

This all makes good sense to me. But the idea that we can step back and assess and override our feelings assumes that we can transcend this cluster of evolved, stupid neural systems. Similarly, when one speaker in Chile described people’s crazy intuitions about certain market interactions, his audience roared with laughter, so certainly we were capable of thinking differently.

One sees this a lot—a psychologist (or a philosopher, or a neuroscientist) presents a mental quirk or limitation of humans and then draws a pessimistic conclusion about human nature in general, forgetting for the moment that their argument presupposes that we are also savvy enough to appreciate when things go awry. The same point applies in other domains, where certain biases lead people to make errors, such as over-estimating the likelihood of rare but salient events, like shark attacks. These are cool findings but we shouldn’t forget that the same creatures who make these mistakes are also smart enough to identify and laugh at them.

But what about a milder version of the moral irrationality position? There’s nothing incoherent about arguing that much of the time we are irrational, or that some people are more irrational than others. Indeed, both claims are almost certainly true. What’s more controversial, but still possible, is that certain types of people are less rational.

Psychologists and other social scientists used to argue for the irrationality of women and minorities, particularly of African descent—arguments that are now understood to be false. Now they make this claim about political conservatives. One popular theory is that conservatives are highly prone to “system justification,” which leads them to endorse, as John Jost and his colleagues put it “a fairly wide range of rationalizations of current social, economic, and political institutions and arrangements.” Note the word “rationalizations,” as opposed to actual arguments or reasons. Conservative policies—such as opposition to affirmative action and income redistribution—are seen as the products of cognitive biases.