T he “facts” about poverty can be deceiving. In her magisterial book Behind the Beautiful Forevers , Katherine Boo tells the stories of the inhabitants of a Mumbai slum on the edge of a sewage lake who lack jobs, housing, running water, health care, education, and police protection. It is not unusual to see rats and frogs fried for dinner, feet covered with black fungus, and maggots breeding in wounds wrought by trash-picking. Yet, Boo writes, “almost no one in the slum was considered poor by official Indian benchmarks. … [They] were thus part of one of the most stirring success narratives in the modern history of global market capitalism.” Some success. Our government’s own count of the poor, while not denying their existence, also minimizes their number—not by undercounting them (though that’s a factor, too) but by setting the poverty bar so low that tens of millions of poor Americans are not accounted for. This miscategorization not only paints a picture of a more prosperous...