ARE you feeling anxious and afraid? Little wonder. Our world has been convulsed in the past three weeks by horrifying acts of terrorism and murder: first, Paris, then Planned Parenthood and, finally, the slaughter on Wednesday of 14 people at a social services center in San Bernardino, Calif., by a married couple who appear to have been inspired by Islamist extremists.

The message of these attacks is powerful: You are not safe anywhere.

That, after all, is the whole point of terrorism: to subvert our sense of the normal, to make us afraid of improbable dangers and invite us, in our fear, to overreact in ways that are destructive to our lifestyle and that will not make us any safer.

We really can’t help it. For better or worse, humans are hard-wired to detect unpredictable and novel events, like surprising rewards and terrifying punishments. They grab our attention and take precedence over the ordinary — and safe — aspects of our surroundings to which we’ve become habituated. We evolved this way over millions of years, in part, to help us identify and learn about new and valuable resources and dangers in our environment. Even if a particular danger is improbable, we can’t afford to ignore it.

But that doesn’t mean that we should check our brain at the door once we’ve been traumatized and let ourselves be ruled by our emotions.