There is a paradox about macro- economic demand management in an open economy. A central bank can raise interest rates and yet monetary conditions end up looser. In a world of open capital markets, the central banker's principal instrument for constraining economic excesses – setting interest rates – has been blunted.

The problem is that the authorities have had only one weapon in their monetary armoury. They need two. It is time to give them the power to influence the supply of credit, to augment interest rate policies which mostly affect the demand for credit.

With vast cross-border capital flows, the tasks facing monetary policymakers have become much more complex. They have to manage an inflation target over time while avoiding risks to the financial system. Monetary policy works best if changes in the policy stance are smoothly communicated through the banking system as a whole. If the waxing and waning of global capital flows distort this process, monetary policy is much less effective.