Beijing

It's a rare afternoon in the Chinese capital when smog hasn't blocked the skies, and one of China's most famous economists is in a sanguine mood. The economy is in trouble as the Communist Party heads for a once-in-a-decade transfer of power while prosecuting its former golden boy, Bo Xilai, on criminal charges. Worried investors want signs that Beijing remains committed to growth—and the sign they'd most like to see is a big Keynesian stimulus.

Zhang...