Predictably Irrational is a book by Dan Ariely that explores the ways in which people's behavior deviates from what classical economics would predict. The book is structured around a series of experiments and observations that Ariely conducted to better understand how people make decisions. He covers a wide range of topics, including the effects of anchors and framing on decision making, the role of social norms in shaping behavior, and the ways in which people's emotional states can affect their choices.

One of the main themes of the book is that people are not always rational actors, and that they often make decisions based on emotional, social, and psychological factors rather than purely economic ones. Ariely argues that these irrational decision-making patterns are predictable, and that they can be understood and even influenced by the way in which information is presented and by the context in which decisions are made.

Throughout the book, Ariely uses a combination of scientific research and anecdotes to illustrate his points and to provide insight into the ways in which people's irrationality can be predicted and understood. He also offers practical tips for how to make better decisions and how to avoid common pitfalls that can lead to irrational behavior.

In addition to discussing the various factors that influence decision making, Ariely also explores the ways in which people can be influenced by their past experiences, the power of free samples, and the impact of expectations on behavior. He also examines the role of social norms in shaping behavior and the ways in which people can be influenced by the actions and expectations of others.

Overall, Predictably Irrational is a thought-provoking and engaging read that challenges readers to think about their own decision-making processes and how they can be influenced by factors beyond their conscious awareness. It is a valuable resource for anyone interested in psychology, economics, or the ways in which people make choices.