It’s not surprising that Treasury Secretary Geithner’s recent G‑20 proposal that governments agree to keep their current-account balances (either surplus or deficit) within 4 percent of GDP has met with resistance. After all, it assumes governments can and should manage the buying, selling, and investment decisions of hundreds of millions of Americans and billions of people worldwide. But I marvel at how deeply Chinese Vice Foreign Minister Cui Tiankai’s tongue must have been planted in cheek when he uttered this rich rejection of Geithner’s idea: “The artificial setting of a numerical target cannot but remind us of the days of a planned economy.” If the shoe fits.…