When French sociologist Lo c Wacquant signed up at a boxing gym in a black neighborhood of Chicago's South Side, he had never contemplated getting close to a ring, let alone climbing into it. Yet for three years he immersed himself among local fighters, amateur and professional. He learned the Sweet science of bruising, participating in all phases of the pugilist's strenuous preparation, from shadow-boxing drills to sparring to fighting in the Golden...