Predictably Irrational by Dan Ariely Why do our headaches continue after we take a one-cent aspirin but disappear when we take a fifty-cent aspirin? Why do we spend more money on a lavish meal but cut coupons to save twenty-five cents on a can of soup? When it comes to making decisions in our lives, we think we're making smart, rational choices. But are we? In this newly revised and expanded edition of the groundbreaking New York Times bestseller, Dan Ariely disproves the common belief that we behave in fundamentally rational ways. From drinking coffee to losing weight, from buying a car to choosing a romantic partner, we consistently overpay, underestimate, and procrastinate. Yet these misguided behaviors are neither random nor senseless. They're systematic and predictable—making us predictably irrational.