Sometimes you’re better off letting people lie to you, and even lying to yourself. That’s the surprising, but well-argued, conclusion of Useful Delusions. Some people, for example, corresponded with romantic pen pals for years, sending money and other gifts. But their pen pals didn’t actually exist. They were fictions created in a scam called the Church of Love. Were the gift-givers, then, victims of fraud? You’d think so. But some of them resented that the letter-writers had been arrested and even testified in their defense. The belief they were in a loving relationship had been a positive one, they said.

Okay, that’s an extreme case. But the authors point out so many other ways in which self-deception is actually helpful to us.

Most of us act as if we’re happy to see customers and co-workers, even when we aren’t—and they do the same for us. We get more enjoyment out of things we pay more for, even when they’re identical to lower-priced options. Patients who believe they’ll live longer than the data would suggest do, in fact, tend to live longer.

Here’s the thing: Our brains are great at passing on our genes to the next generation, and not so great at perceiving objective reality in every detail. The mental shortcuts baked into our operating system give us a somewhat accurate and mostly useful idea of what’s going on. When we find ourselves in a truly dystopian situation like being a civilian during a genocidal civil war, experiencing a ritual for bulletproofing might actually help to keep you alive. On the other hand, patriotic and religious beliefs can preserve an entire society even as they cost individual people their lives.

This book is well-organized, and easy to pick up again after a break. A few fascinating stories of extreme self-deception (like the pen pals) weave throughout the narrative, showing up to illustrate a point or to delve deeper into the case study. Since it isn’t designed for academic use, there’s no index—but the well-planned organization of chapters certainly helps.

I am grateful to the authors, the publisher, and NetGalley for a free advance review copy.