Excerpted from “Rationality: Why It Seems Scarce and Why It Matters” by Steven Pinker, Johnstone Family Professor of Psychology.

Rationality ought to be the lodestar for everything we think and do. (If you disagree, are your objections rational?) Yet in an era blessed with unprecedented resources for reasoning, the public sphere is infested with fake news, quack cures, conspiracy theories, and “post-truth” rhetoric. We face deadly threats to our health, our democracy, and the livability of our planet.