Book excerpt: Corruption, crime, economic inequality, religious fundamentalism, financial crises, environmental degradation, population ageing, gender inequality, large-scale migration... This book tackles many of the most pressing problems facing societies today. The authors demonstrate that similar social mechanisms lie behind many of these seemingly disparate problems. Indeed, many societal problems can be traced back to behaviours that are perfectly rational and often well-intended from an individual perspective. Yet, taken together these behaviours can – paradoxically – give rise to unintended and undesirable outcomes at the society level. In addition to addressing the causes of societal problems, the book explains why some problems rank higher on the public agenda than others. Moreover, it is shown how government intervention may sometimes provide a cure, yet other times exacerbate existing problems or create new problems of its own. This book includes an extensive amount of data on trends and geographic variation in the prevalence of different problems, as well as telling examples – both recent and historical – from a variety of countries to support its key arguments. Employing a bold multidisciplinary approach, the authors draw on insights from across the social sciences, including sociology, economics, anthropology, criminology, and psychology. Throughout the book, students are introduced to analytical concepts such as free-riding, herding behaviour, principal-agent relations and moral hazard. These concepts are essential tools for better understanding the roots of many societal problems that regularly make headlines in the news. This improved understanding will, in turn, be critical for ultimately finding solutions to these problems.