We're all keynesianos now.

Mexico has made great strides on economic policy.

To be sure, Mr. Carstens [Mexico's minister of finance, Agustin Carstens] believes in the state's capacity to stimulate economic activity. "If you can get the economy going and you have the instruments to do it, it is important that you use them," he told me. Then he added a historic footnote: "But we have limits to how much we can borrow and finance prudently." He went on: "Thinking that we are going to run a fiscal deficit without thinking of how we will finance it? That would be irresponsible."

For a country that has repeatedly gotten itself into fiscal and monetary trouble by running up big budget deficits, this is a tectonic shift in thinking.