This book was recommended by a friend, and I’m so glad I read it. It works both as a trade paperback about a fascinating psychological topic (the cognitive basis and/or origins of morality), and as a diagnosis of some of the societal and political dysfunction that seems to be affecting America today. Jonathan Haidt has been in the news and has published various op-eds, so I will dispense with an introduction, or even a summary of the book. I want simply to make basic points about the book, one of which I’m sure Haidt would acknowledge the validity, and one which he might not.

The book in concerned with moral psychology: studying moral judgments from a psychological perspective, just as we might study reasoning, perception, language, or even beauty from a psychological perspective. I think it would have helped the book to be a little more clear about the nature of the inquiry. The book is about how people think about morality. It is not about morality itself. So while moral psychology can tell us a great deal about how people think and talk about about right and wrong, it can’t tell us what morality is. Sometimes I feel the author lures the reader into a bit of reductionism, as if psychology has pulled back the curtain on morality and discovered that there’s nothing there. (Again, this is not stated explicitly in the book, but it’s a conclusion I fear people will draw all too readily.)

Let me illustrate the difference with something that I have more experience with than I’d like: teaching algebra. Now, the whole reason that we teach algebra is that we believe it has an objective, universal reality. There is something “out there” that we can discover. (Let me hedge: “out there” might just be the logical implications of some set of propositions we decide to accept for the sake of argument.) Math is justified by arguments and proofs.

How we think about math is something entirely different. For instance, 99% of beginning mathematicians will have no problem with this simplification step:

\[x\cdot (y + z)\] \[x\cdot y + z\]

Although this is incorrect mathematically, it’s absolutely the way people think about math. If you were going to explain the psychology of math, you’re going to have to explain why the simplification step above is so alluring to human brains. If you don’t explain why people get it wrong so often, you’re not explaining the psychology of math.

If you were simply talking about mathematics, then you would only have to prove why it is that \(x\cdot (y + z) = x\cdot y + x\cdot z\). (Then if you had to you could show that this is generally not equal to \(x\cdot y + z\)).

Back to Haidt: yes, absolutely, let’s understand how people think and talk about morality. But let’s make sure we remember that this doesn’t necessarily tell us anything about morality itself—just like understanding how kids think about algebra doesn’t tell us anything about algebra itself. The claims made are about the human mind, not about moral reality.

Then the second, more substantial criticism of the book comes from the latter part, where Haidt motivates (attempts to motivate) his various moral foundations in terms of evolutionary biology. This is a fraught process to begin with, because it’s always easy to tell a “just so” story in biology. So most of my critique here will be familiar.

For instance, Haidt claims that the “Care/harm” moral foundation comes from our mammalian heritage. Mammals care for their young, and it it’s a supposedly modest generalization for us to be able to care for our families, our extended families, our tribes, and then eventually for all members our species. And this works out evolutionarily because our species survives better if you share your mammoth steak with me when I need it, and I share my mammoth steak with you when you need it. (This is sort of the altruistic counterpart of honeybees and their self-sacrifice for the greater good.)

There are many objections to be raised, as is true of any just so story. But the most general objection I can think of is that any evolutionary argument about morality is going to be so vague that it will be entirely useless. Here’s the problem: humans are the apex predators. Even if we can’t kill a hippo with our bare hands, we can invent tools to do it for us. (I read a charming popular science piece a while back that observed that humans used generally to hunt by the slow pursuit method. We were so resilient that we could just follow an animal until it got tired and has to sleep; then we would kill it. The punchline, of course: we’re terminators!) All to say: we’re the ones at the top of the food pyramid.

Morality is also a uniquely human property. And so we have a frustrating confound: anything in our evolutionary history that might be argued to give rise to morality can just as well be argued to be they key to making us the apex predators. So it’s always going to be possible to tell some story that connects morality to evolutionary advantage. You’re just never going to be able to test which story is true.