Olivier Sibony And You're About to Make a Terrible Mistake

Every day, brilliant people in boardrooms, courtrooms, hospitals, and governments make decisions they are absolutely certain are right — and turn out to be catastrophically wrong. Not because they lacked information. Not because they were careless. But because the human mind is wired to fail in ways that feel, from the inside, exactly like success. You're About to Make a Terrible Mistake is a comprehensive summary of Olivier Sibony's landmark work on the hidden architecture of bad decisions. Drawing on decades of behavioral economics research, real-world corporate case studies, and the pioneering work of Nobel laureate Daniel Kahneman — with whom Sibony collaborated directly — this summary distills one of the most important books on decision-making of the 21st century into a deeply detailed, highly readable guide for anyone who makes consequential choices. Across thirteen richly developed chapters, you will encounter the nine cognitive traps that silently corrupt judgment at every level of organizational life: the overconfidence that turned Motorola's $5 billion Iridium satellite network into a spectacular bankruptcy; the anchoring effects that determine legal sentences before a single argument is heard; the groupthink dynamics that contributed to the Challenger and Columbia disasters; the motivated reasoning that caused Wall Street analysts to believe their own conflicted research; and the story traps that made Nokia dismiss the iPhone as a niche product for early adopters. But this is not simply a catalogue of failure. Its central and most radical argument is this: knowing about your biases will not help you overcome them. The real solution lies not in better people, but in better processes — in the deliberate design of decision architecture that reduces the impact of cognitive bias at the level of the system, not the individual. Readers will find practical, evidence-based tools — pre-mortems, reference class forecasting, structured disagreement, the Mediating Assessments Protocol, red team processes, and decision quality frameworks — each explained with the depth and context needed to actually apply them. Updated with research through 2026, this summary goes beyond the original text to incorporate the latest findings from behavioral economics, organizational psychology, and management science. Whether you lead a team of five or an organization of fifty thousand, the decisions you make shape outcomes that matter. This book will change how you think about thinking — and give you the tools to build something better than confidence: genuine decision quality.