Willard Quine, one of the most influential philosophers of the 20th century, famously thought that there was no discontinuity between philosophy and the natural sciences. Indeed, he went so far as to suggest that epistemology, for instance, will eventually become a branch of psychology.

I think he was seriously mistaken. While it is certainly true that there are continuities and reciprocal positive interactions between the sciences and philosophy, the two are fairly clearly distinct enterprises. Proof can easily be found in Quine’s own papers: I am a scientist as well as a philosopher, and every single one of his paper that I came across looks nothing at all like a science paper, but instead is very much written in an unmistakably philosophical style.

At any rate, I was reminded of this while reading a fascinating, in-depth article by Tamsin Shaw in the New York Review of Books, covering or referring to the claims of a number of books by psychologists that have recently made much noise to the effect that human beings are not rational, but rather rationalizing, and that one of the things we rationalize most about is ethics.

The authors covered by Shaw’s essay include Jonathan Haidt, Steven Pinker, Paul Bloom, Joshua Greene and a number of others. All of them should be pleased by Quine’s remarks on epistemology, and all of them make the same kind of fundamental mistake, regardless of the quality of their empirical research. It is that fundamental mistake I wish to explore here.

But let me begin by summarizing the most pertinent points made by Shaw, an Associate Professor of European and Mediterranean Studies and of Philosophy at NYU. (I will skip the parts of the article that deal with the recent empirical and moral failures of the psychological profession itself. While fascinating, they are tangential to my aims here.)

The first author to fall under scrutiny in Shaw’s sharp analysis is Joshua Greene, who has made a career (see, for instance, his Moral Tribes: Emotion, Reason, and the Gap Between Us and Them) of claiming that his neuroscientific data can test ethical theories, concluding that there is empirical evidence for utilitarianism. (This, in my mind, is a colossal example of what in philosophy is known as a category mistake, after the felicitous phrase introduced by Gilbert Ryle.)

Here is Shaw: “Greene interpreted these results in the light of an unverifiable and unfalsifiable story about evolutionary psychology … Greene inferred … that the slower mechanisms we see in the brain are a later development and are superior because morality is properly concerned with impersonal values … [But] the claim here is that personal factors are morally irrelevant, so the neural and psychological processes that track such factors in each person cannot be relied on to support moral propositions or guide moral decisions. Greene’s controversial philosophical claim is simply presupposed; it is in no way motivated by the findings of science. An understanding of the neural correlates of reasoning can tell us nothing about whether the outcome of this reasoning is justified.”

Let me interject here with my favorite example of why exactly Greene’s reasoning doesn’t hold up: mathematics. Imagine we subjected a number of individuals to fMRI scanning of their brain activity while they are in the process of tackling mathematical problems. I am positive that we would find the following (indeed, for all I know, someone might have done this already):

There are certain areas, and not others, of the brain that lit up when someone is engaged with a mathematical problem.
There is probably variation in the human population for the level of activity, and possibly even the size or micro-anatomy, of these areas.
There is some sort of evolutionary psychological story that can be told for why the ability to carry out simple mathematical or abstract reasoning may have been adaptive in the Pleistocene (though it would be much harder to come up with a similar story that justifies the ability of some, people to understand advanced math, or to solve Fermat’s Last Theorem).
But none of the above will tell us anything at all about whether the people in the experiment got the math right. Only a mathematician — not a neuroscientist, not an evolutionary psychologist — can tell us that.

Next: Jonathan Haidt, who “denies that reason ordinarily plays any part in motivating moral judgments, seeing it rather as a post-hoc means of justifying the intuitions we form quickly and unreflectively.” In his The Righteous Mind: Why Good People Are Divided by Politics and Religion, he famously empirically identified six areas of moral concern for the people he surveyed: care vs. harm, fairness vs. cheating, loyalty vs. betrayal, authority vs. subversion, sanctity vs. degradation, and liberty vs. oppression.

Interestingly, he also found that self-professed “liberals” (as opposed to “conservatives”) in 21st century America consider only a subset of the xis dimensions to belong to morality, and tend to be focused especially on the care vs harm dimension. Moreover, he writes that “across many scales, surveys, and political controversies, liberals turn out to be more disturbed by signs of violence and suffering, compared to conservatives and especially to libertarians.”

Now, so far so (almost) good. These are empirical findings, and although a recent survey of psychological research (mentioned in Shaw’s article) has found that only about 40% of the results of empirical psychological studies can be confirmed upon replication, let us take them at face value.

The first, obvious, objection, is that Haidt is taking “liberal” and “conservative” to be fairly universal categories, at the least implicitly. But of course these terms have the meaning they have only in the United States, and only for the last few decades. What it meant to be liberal, progressive, or something else, in the United States in the past was different, and it certainly is different in other places on the planet (and a fortiori in other centuries, both in the US and elsewhere).

Setting that aside, however, it should be obvious that there is more than normative interpretation of Haidt’s findings, besides the one he himself suggests (and why would a psychologist get in the business of prescribing moral stances anyway?). Haidt claims that liberals should try to appreciate the “richer” moral landscape contemplated by conservatives. Yes, or one could invite conservatives and especially libertarians to be a bit less callous about the harm done to other people, or even to consider that perhaps they may be mistaken when they think that respect of authority, or “sanctity,” are valid moral categories at all (again, think Ryle).

As Shaw puts it: “In offering this moral counsel [Haidt] presupposes that the norm of cooperation should take precedence over the values that divide us.” Right. But on what bases does he make such presupposition? Empirical ones? That would be begging the question. Philosophical one? But then he would be outside of his proper area of expertise.

Third up: Steven Pinker. In his The Better Angels of Our Nature: Why Violence Has Declined he again straddles the empirical/descriptive and the normative/prescriptive divide.

(Please note that I (and likely Shaw, I don’t know, I haven’t asked her) am not advocating a sharp boundary between is and ought. I am simply saying — with David Hume — that one can’t simply jump from one domain to the other without argument of justification.)

Pinker argues that moral progress is the result of rational deliberation. No objections here. But, as Shaw points out, he holds to an explicitly narrow conception of rationality: “by ‘rationality’ he means specifically ‘the interchangeability of perspectives and the opportunity the world provides for positive-sum games,’ rather than any higher-order philosophical theory. He allows that empathy has played a part in promoting altruism, that ‘humanitarian reforms are driven in part by an enhanced sensitivity to the experiences of living things and a genuine desire to relieve their suffering.’ But nevertheless our “ultimate goal should be policies and norms that become second nature and render empathy unnecessary.”

Pinker, in effect, just like Greene and Haidt, doesn’t seem to be aware (or perhaps doesn’t care) that he is building into his allegedly objective empirical assessment plenty of unexamined philosophical assumptions. As Daniel Dennett famously put it, there is no such thing as philosophy-free science, there is only science whose philosophical baggage goes unexamined.

Which brings me to the fourth psychologist under examination: Paul Bloom. He also is no friend of empathy, but he also begins with a reasonable, empirically substantiated, perspective, and then jumps off the philosophical window, so to speak.

Bloom, in his Just Babies: The Origins of Good and Evil, argues that human beings start out with an innate, rudimentary, sense of morality, based on empathy and a non articulated concept of fairness directed mostly at their care takers. But what it means to become an adult, Bloom says, is to gradually expand our sense of morality to include strangers, and we do this chiefly by reason, because if anything our instincts make us weary of people we don’t know, especially if they look different from us.

I’m on board thus far, and so is Shaw. But then she correctly remarks: “But Bloom’s view of reasoning, like Haidt’s and Pinker’s, seems oddly restrictive: he equates it with impartiality in the sense of the development of ‘systems of reward and punishment that apply impartially within the community.’ The norm of cooperation is again presupposed as the fundamental means for deciding which of our moral intuitions we should heed. When discussing the more stringent moral principles that Peter Singer, for instance, takes to be rationally required of us concerning our duties to distant strangers, Bloom dismisses them as unrealistic in the sense that no plausible evolutionary theory could yield such requirements for human beings.” But of course evolution is what provided us with the very limited moral instinct that Bloom himself concedes need to be expanded through the use of reason! He seems to want to have it both ways: we ought to build on what nature gave us, so long as what we come up with is compatible with nature’s narrow demands. But why?

Let me quote once more from Shaw, who I think puts her finger precisely where the problem lies: “it is a fallacy to suggest that expertise in psychology, a descriptive natural science, can itself qualify someone to determine what is morally right and wrong. The underlying prescriptive moral standards are always presupposed antecedently to any psychological research … No psychologist has yet developed a method that can be substituted for moral reflection and reasoning, for employing our own intuitions and principles, weighing them against one another and judging as best we can. This is necessary labor for all of us. We cannot delegate it to higher authorities or replace it with handbooks. Humanly created suffering will continue to demand of us not simply new ‘technologies of behavior’ but genuine moral understanding. We will certainly not find it in the recent books claiming the superior wisdom of psychology.”

Please note that Shaw isn’t saying that moral philosophers are the high priests to be called on, though I’m sure she would agree that those are the people that have thought longer and harder about the issues in question, and so should certainly get a place at the high table. She is saying that good reasoning in general, and good moral reasoning in particular, are something we all need to engage in, for the sake of our own lives and of society at large.

And this is, I think, where the problem lies with both cognitive and moral psychology. It is an unqualified positive contribution of these fields of science to make us appreciate just how much unrecognized bias goes into human thinking. We do, indeed, rationalize more often then we think rationally. But that is not a reason to abandon philosophy, critical thinking, or trust in reason. On the contrary: it provides us added, urgent motivation to do so.

Here is another analogy I like to bring up in this context: psychological research has shown that people are really bad at reasoning about probabilities, a simple fact on which the entire gambling and lottery industries are built and thrive. But it would be odd, and indeed positively dangerous, for psychologists to tell us to stop teaching probability theory to people. On the contrary, it is precisely because human beings are so easily fooled in this department that we need to teach statistics and probabilities.

When people like Haidt and other psychologists claim that the speech of liberals and conservatives, or of advocates of science and their opponents, follows the same patterns and are affected by the same cognitive biases, they are absolutely right. But they are missing — willfully or not — the crucial element that, at the least some of the times, separates those positions: the epistemic one.

For instance, if you take a look at some of my debates with creationists (here is one example) and you examine them from a purely psychological perspective, you will not see much difference between the creationist and myself. We both make use of humor, attempt to diminish the stature of our opponent, possibly engage in a couple of informal fallacies (which, sometimes, are actually not fallacious), and so forth.

But the fact remains that I’m closer to the truth than any creatonist is. Why? Because it is a fact, as much as science can ascertain facts, that the earth is billions, not thousands, of years old. Period, end of discussion. But if you look at the debate from a purely descriptive, epistemically neutral, perspective, you won’t be able to see that. You may sound more ecumenical and fair minded to outsiders (“see? Prof. Pigliucci is engaging in the same kind of rhetoric as his creationist opponent), but you will do so at the cost of a great casualty: truth.

MASSIMO PIGLIUCCI IS THE K.D. IRANI PROFESSOR OF PHILOSOPHY AT THE CITY COLLEGE OF NEW YORK. HIS BACKGROUND IS IN EVOLUTIONARY BIOLOGY AND THE PHILOSOPHY OF SCIENCE, THOUGH HE HAS RECENTLY DEVELOPED A KEEN INTEREST IN STOICISM (AT HOWTOBEASTOIC.ORG). HIS MOST RECENT BOOK (CO-EDITED WITH MAARTEN BOUDRY) IS “PHILOSOPHY OF PSEUDOSCIENCE: RECONSIDERING THE DEMARCATION PROBLEM” (UNIVERSITY OF CHICAGO PRESS, 2013). HIS OTHER WRITINGS CAN BE FOUND AT PLATOFOOTNOTE.ORG.