Last year saw 250 million people added to the ranks of the starving and malnourished, pushing the world total past one billion, or one in every six people on the planet.1 As I read reports of the dramatic upsurge I was reminded of a rainy afternoon in Cambridge two summers ago, when I interviewed Amartya Sen, the Harvard professor who had won the Nobel prize for economics in 1998 for his work on poverty and famine. According to Sen, hunger was not only entirely preventable but profoundly unreasonable.

I had come to Amartya Sen’s house to discuss the recent efforts of the Bill and Melinda Gates Foundation and the World Food Programme to help eradicate world hunger by means of a new programme, called Purchase for Progress. And while our discussion began with the specifics of global food aid, it eventually ranged beyond the particulars of poverty.

“I believe in reason,” Sen told me. “There are those who want to repress reason: Christian, Muslim, and Hindu fundamentalists, and those who pick a totem market economy, the liberal economic state. These are all anti-reason.”

Ironically, at the …