Some 2.5 billion human beings live in severe poverty, deprived of such essentials as adequate nutrition, safe drinking water, basic sanitation, adequate shelter, literacy, and basic health care. One third of all human deaths are from poverty-related causes: 18 million annually, including over 10 million children under five.

However huge in human terms, the world poverty problem is tiny economically. Just 1 percent of the national incomes of the high-income countries would suffice to end severe poverty worldwide. Yet, these countries, unwilling to bear an opportunity cost of this...