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We, the leaders of the G20, declare that our decisive, concerted and brilliant policy action has helped arrest the decline in the global economy, stabilise financial markets and improve the outlook for growth and jobs. We have agreed to develop co-operative and co-ordinated exit strategies from our extraordinary fiscal, monetary and financial sector support (but not yet), to crack down on bankers' bonuses (sort of), to beef up capital controls (eventually), to secure a rebalancing in global demand (at some point), and to cure the world of all diseases…"

This – or some such guff – will introduce the communiqué released after next week's summit of global leaders in Pittsburgh. But rarely has the gulf between aspiration and reality looked so great. Behind...