This is an expanded and revised edition of the author’scritically acclaimed volume Nuts and Bolts for the Social Sciences. Intwenty-six succinct chapters, Jon Elster provides an account of the nature of explanationin the social sciences; an analysis of the mental states –beliefs, desires, andemotions – that are precursors to action; a systematic comparison ofrational-choice models of behavior with alternative accounts; a discussion ofwhat the social sciences may learn from neuroscience and evolutionary biology;and a review of mechanisms of social interaction ranging from strategicbehavior to collective decision making. He offers an overview of keyexplanatory mechanisms in the social sciences, relying on hundreds of examplesand drawing on a large variety of sources – psychology, behavioral economics,biology, political science, historical writings, philosophy, and fiction. Inaccessible and jargon-free language, Elster aims at accuracy and clarity whileeschewing formal models. In a provocative conclusion, he defends the centralityof qualitative social science in a two-front war against soft (literary) andhard (mathematical) forms of obscurantism.