In their recent book about tough decisions, "Hard Call," John McCain and his coauthor and top aide, Mark Salter, devote a memorable chapter to Branch Rickey, the general manager of the Brooklyn Dodgers. Rickey is best remembered for integrating baseball by bringing up Jackie Robinson. But Rickey is also the author of a fine piece of advice in this commencement season, that "luck is the residue of design." This idea of planning with an eye on serendipity is one of the least-appreciated skills any leader can possess. It helps explain not just why Barack Obama is the presumptive Democratic nominee, but why McCain is actually the candidate who may end up dramatically improving accountability in Washington.

Obama is more than just the Jackie Robinson of presidential politics. He's the Prince Serendip of 2008, the fairy-tale character blessed by good fortune. The gods of scheduling were smiling on him this year. Imagine if the Rev. Jeremiah Wright Jr. story had exploded in January and February instead of in March and April, when he had a cushion of delegates. Obama's also lucky the story didn't first ignite this October, when it will likely come back only as a one-day rerun instead of a two-week conflagration that would have destroyed him so close to the election. Or consider what would have happened if Florida had kept its primary on Super Tuesday, giving Hillary Clinton real momentum. And had West Virginia been early this year, Obama might have looked as if he couldn't win white supporters, which in turn would have dissuaded black voters from giving him a chance.

But Barack, which means "blessing" in Swahili (and Arabic), has made much of his own luck. He drew up elaborate blueprints for competing in almost every state, while Clinton inexplicably had no Plan B if she failed to wipe out Obama on Super Tuesday. Her decision not to contest caucus states was one of the most boneheaded moves in recent political history. It allowed Obama to store delegates for the rough weather ahead. Obama also hired much better than Hillary, who has been a strong candidate but a weak manager of a monumentally misconstrued campaign.

McCain has had his own good luck in 2008, mostly in the form of weak competition in the GOP primaries. But we're learning that his seat-of-the-pants approach—his faith in serendipitous events—can lead him off course. His reliance on instinct makes him simultaneously destructive and creative. Last Thursday, for instance, he rashly piled on Obama after President Bush violated a longstanding bipartisan tradition by engaging in domestic political attacks while on foreign soil. Appearing before the Israeli Parliament, Bush conjured Hitler, Chamberlain and "appeasement." The White House later claimed implausibly that it was aiming for Jimmy Carter, who wants talks with Hamas, but hit Obama, who doesn't. Obama then displayed a bit of jujitsu, using McCain's endorsement of Bush's attack to pursue his potent theme that McCain represents a third term for a seriously unpopular president. And he delivered his retort with "bring it on" vigor.

Reasonable people can differ on high-level talks with our enemies, but not on sliming your opponent as an appeaser. This cheap politics—aimed at mindless hawks and nervous Jewish voters—came only hours after McCain delivered a visionary speech that made news for setting a timetable for leaving Iraq in 2013 (an additional $1 trillion down the road), but was much more important for its commitment to genuine transparency in government. After pledging to abandon Bush's pernicious habit of attaching signing statements to bills and once again promising weekly press conferences, McCain came out for a truly big idea that almost no one noticed: "I will ask Congress to grant me the privilege of coming before both houses to take questions, and address criticism, much the same as the prime minister of Great Britain appears regularly before the House of Commons."

As C-Span viewers of the weekly British Question Time can attest, this would be revolutionary, even if our version proved far tamer. (Canada, Australia, New Zealand and Sweden use this approach, too.) By moving us a bit closer to a parliamentary system, McCain would strike a major blow for real debate and democracy. A pointed question from an opposition leader (e.g., "Why is talking to the leader of a major country like Iran appeasement?") would make a much bigger splash than the same question from a reporter. Imagine this being televised a year from now. Question Time would be great theater that would strengthen ties between the branches.