The Upside of Irrationality: The Unexpected Benefits of Defying Logic is a book published in 2010 by behavioral economist Dan Ariely. This is Ariely's second published book, after he authored Predictably Irrational: The Hidden Forces That Shape Our Decisions.

Dan Ariely is an Israeli James B. Duke Professor of Psychology and Behavioral Economics at Duke University and is the founder of The Center for Advanced Hindsight and co-founder of Kayma BEworks, Timeful, Genie and Shapa. Ariely is also associated with Qapital and Lemonade in the capacity of Chief Behavioral Economist and Chief Behavioral Officer, respectively. Ariely's TED talks have been viewed over 10 million times. He is the author of Dollars and Sense, Predictably Irrational, The Upside of Irrationality, and The Honest Truth about Dishonesty. All three books became New York Timesbest sellers. He also wrote two semi-books: Irrationally Yours – an illustrated collection of his immensely popular The Wall Street Journal advice column, “Ask Ariely” – and Payoff, a short TED book. Ariely was involved in the movie (Dis)Honesty: The Truth About Lies as both a producer and a participant.