What turns so many cadres bad in contemporary China? Busy purging a generation of corrupt officials from the Communist Party, Chinese President Xi Jinping may not have much time to worry about causes at the moment. This week he's concerning himself with political fallout from the detention of Zhou Yongkang — China's retired (and still-feared) security chief and formerly ninth-ranking member of the Politburo — for "serious discipline violations," as the state newsmedia describes them.

So far, nobody knows the precise charges. But in Xi's China, where corrupt officials are paraded through the media on a regular basis, it's almost certain they will involve obscene amounts of money and abuses of power. The bigger question is what prompted Zhou's corruption. Slowly, in Chinese newspapers and social media, that's becoming the central issue in Xi's massive anti-graft campaign.

Zhou, a man with a permanent, central casting scowl, should have embodied the Communist Party's meritocratic ideal. He was born to modest circumstances and worked his way up through the powerful, state-owned oil and gas industry, where his talents were recognized and promoted to the alleged benefit of party and state.