Rupert Murdoch has demoted his son, James Murdoch, amid continuing fallout from the phone-hacking scandal at the British newspapers overseen by James. That tough-minded decision highlights the contradictions in the News Corp. chief's managerial M.O., writes Geoff Colvin. "Sometimes he makes business decisions purely with his head, canny and shrewd, occasionally ruthless. That's what he did this time," Colvin writes of the elder Murdoch. "But sometimes he makes giant decisions with his heart, appearing misguided or just nuts."