On every measure, mankind is enjoying a golden age. We are living longer, happier, healthier lives than our grandparents could have imagined. The improvements are most dramatic in developing countries where, as in Europe a century ago, agrarian economies are turning into consumer societies.

What has made this transformation possible? What is lifting our species to an unprecedented level of wealth? What is reducing infant mortality, educating girls, creating leisure time, incentivizing eco-friendly technologies? Free trade. The spectacular improvements in literacy, longevity and calorie intake have coincided with the post-war development of a global market.