Predictably Irrational: The Hidden Forces That Shape Our Decisions is a 2008 book by Dan Ariely, in which he challenges readers' assumptions about making decisions based on rational thought.Book review of Dan Ariely's Predictably Irrational in the New York Times Sunday edition.Cost-benefit analysis is a systematic process for calculating and comparing benefits and costs of a decision.An honor code or honor system is a set of rules or ethical principles governing a community based on ideals that define what constitutes honorable behavior within that community.Behavioral economics explains why we procrastinate, buy, borrow, and grab chocolate on the spur of the moment.Intuition is the ability to acquire knowledge without inference and/or the use of reason.