Because it worked so well last time.
To wit, what does it mean for the world economy if America now has its first protectionist President since Herbert Hoover?
The smell of trade war is suddenly in the air. Mr. Obama slapped a 35% tariff on Chinese tires Friday night, and China responded on the weekend by threatening to retaliate against U.S. chickens and auto parts. That followed French President Nicolas Sarkozy's demand on Thursday that Europe impose a carbon tariff on imports from countries that don't follow its cap-and-trade diktats. "We need to impose a carbon tax at [Europe's] border. I will lead that battle," he said.
Mr. Sarkozy was following U.S. Energy Secretary Steven Chu, who has endorsed a carbon tax on imports, and the U.S. House of Representatives, which passed a carbon tariff as part of its cap-and-tax bill. This in turn followed the "Buy American" provisions of the stimulus, which has incensed much of Canada; Congress's bill to ban Mexican trucks from U.S. roads in direct violation of Nafta, prompting Mexico to retaliate against U.S. farm and kitchen goods; and the must-make-cars-in-America provisions of the auto bailouts. Meanwhile, U.S. trade pacts with Colombia, Panama and South Korea languish in Congress.
Through all of this Mr. Obama has either said nothing or objected so feebly that Congress has assumed he doesn't mean it. Despite his pro-forma demurrals, Mr. Obama's actions and nonactions are telling the world that the U.S. is abandoning the global leadership on trade that Presidents of both parties have worked to maintain since the 1930s. His advisers whisper that their man is merely playing a little tactical domestic politics, but he is playing with fire, as the last 80 years of trade history should tell him.