RALEIGH – Remember, right after 9/11, all of those media stories about “why they hate us?” Some of the discussions were informative. Others were insipid. There is a similar debate attracting attention from across the political spectrum right now about why so many countries in the world are so desperately poor.

Left-wing cranks like Ralph Nader and the authors of a loony new screed called Empire contend that inequalities in world living standards are due to exploitation, free trade, and the vestiges of colonialism. Peter Bauer, the pioneering scholar of economic development who died a few days ago just as he was about to be honored by the Cato Institute, had a different reading of the data.

That is, he read the data. He concluded that the primary explanatory variable in economic development wasn’t the existence of trade or a history of colonialism (poverty-striken Ethiopia was only ruled by a foreign power, Italy, for a few years in the late 1930s and early 1940s, for example). It was the existence of market-friendly institutions such as the rule of law and private property that actually correlated with economic progress.

There’s new evidence for Bauer’s thesis in the latest international ranking of economic freedom from The Wall Street Journal. The index breaks countries into four categories: free, mostly free, mostly unfree, and repressed. These categories are based on scores recorded in such areas as taxation, trade restrictions, inflation, property rights, and regulations.

Unfortunately, there aren’t very many free countries. They include the U.S., the U.K., the Netherlands, Ireland, Switzerland, Australia, New Zealand, and Hong Kong. The mostly free countries are far more numerous, and include most of Europe, much but not all of Latin America, a few countries in Asia (Japan, Korea, Thailand, Sri Lanka, Turkey, Oman, Jordan, Israel, and Kuwait), and a handful of African nations (Morocco, Tunisia, Mali, Benin, Namibia, and Botswana).

The rest of the world is unfree – and it shows. Per-capita income in 1998, adjusted for differences in purchasing power, averaged over $21,000 in the free countries and $12,000 in the mostly free countries. But unfree and unrepressed countries each had average incomes below $3,000.

To borrow a notion from Henry Grady Weaver, author of The Mainspring of Human Progress, the real question to ask is not what makes countries poor – as that has been the natural state of most human societies throughout most human history – but rather what makes some countries not poor any more.

The answer cannot be found in natural resources, climate, race, religion, or imperial history. The answer is freedom.