SINGAPORE — Barack Obama's election comes at a moment when a new bit of conventional wisdom is congealing. It concerns the end of America's global dominance.

Who may pick up the slack in providing global leadership? The uncomfortable answer that Obama is likely to confront is this: nobody. America may be damaged, but no replacement is on offer. Europe is self-absorbed, focused on creating whatever kind of entity it ends up deciding to be. China's standard response to any suggestion that it exercise global leadership is to hide beneath its vast internal agenda and plead poverty. No other country comes close to having either the capacity or the ambition.

In the face of a litany of problems — not just financial instability, but also climate change, energy insecurity, potential pandemics, terrorism and the spread of weapons of mass destruction — the prospect of a rudderless world is alarming. What is to be done? And by whom?