Are you an optimist or a pessimist when it comes to the future of human civilisation? Your response may be determined by where you live. In the West, beset by economic stagnation, many see reasons to be fearful. In Asia and Africa prosperity and confidence are on the rise. Stephen Sackur speaks to Kishore Mahbubani, former diplomat turned provocative thinker on globalisation. He sees a world increasingly united by economics, ideas and aspirations. But is that more than just wishful thinking?