A modest effort at "strategic trade" could raise the country's $6 trillion gross domestic product by a few billion dollars, Professor Krugman said.

"Malaysia, Thailand and Indonesia all look vulnerable," Professor Krugman said.

"Pricing to market is not symmetric," Professor Krugman said.

"We've had an acceleration of productivity growth, and it takes a while before people build that expectation into wages," Professor Krugman said.

Which brings me to Professor Krugman's letter, and my reply.

And "that's still the correct answer," Professor Krugman said recently.

"Productivity growth is good wherever it occurs," Professor Krugman said.

Professor Krugman supports the treaty, saying he thinks it will help to keep free-market reformers in power in Mexico.

"If the economy created 500,000 fewer jobs, the Fed would lower interest rates more," Professor Krugman said.

Professor Krugman will now be answering questions for the next hour, so feel free to send him one.