This follows my post where I said central banks should get out of the rate-setting game. Three years ago, I wrote this in a post: Capital mobility is now global. With more inter-connectedness among nations, it is now increasingly imperative that each individual nation's monetary policies be coordinated to ensure smooth economic results system-wide.
1. With global capital mobility, if one country hikes its interest rate to contain domestic inflation, it can attract more capital from overseas, nullifying the hike. Similarly, if the country cuts rates to spur investment, capital might leave the economy for better rates elsewhere.
2. An aggressive money supply policy in one country can spill over excess liquidity into the global system, spreading inflation globally.
3. One country’s active currency management policies artificially inflates/devalues free floating currencies.
4. Because of points 1, 2, and 3, one Central Banker’s monetary policies to cure domestic unemployment might be rendered ineffective.
5. Financial crisis that start in one country can easily spread to other economies.
6. That’s because the same toxic financial security can now have multiple listings in different markets.
7. They can be placed in multiple markets, or owned, by multi-national banks looking for arbitrage opportunities created globally by, among other things, uncoordinated Central Bank policies.
8. Conversely, a domestic bank can itself own multinationally-issued investments.
9. There’s been an explosion in cross-border money laundering.
10. Multinational corporations now also cross-lend funds borrowed elsewhere among subsidiaries located in different jurisdictions.
At the time, I didn't know I was hitting on a trilemma identified much earlier by Mundell and Fleming. Mundell and Fleming’s economic trilemma posits that you can only achieve two of three
objectives desired outcomes in monetary policy: open capital markets, domestic control over monetary policy, and fixed as opposed to floating exchange rates.
Wikipedia mentions that Paul Krugman has stated: "The point is that you can't have it all: A country must pick two out of three. It can fix its exchange rate without emasculating its central bank, but only by maintaining controls on capital flows (like China today); it can leave capital movement free but retain monetary autonomy, but only by letting the exchange rate fluctuate (like Britain – or Canada); or it can choose to leave capital free and stabilize the currency, but only by abandoning any ability to adjust interest rates to fight inflation or recession (like Argentina today, or for that matter most of Europe). "
Three years ago, I wondered whether we needed a global central bank. But now I'm thinking that with a global free market, a domestic central bank still setting interest rates is already an outdated artefact, and sure to cause more harm than beneficial results. If a Central banker really doesn't fully control his domestic monetary policy, whatever he does is sure to cause unintended effects, both for his domestic situation and for those abroad. With global capital mobility, a central banker needs to either give up control over interest rates, or give up all pretension that he has any relevant control over domestic policy. At best, given that whatever a domestic central banker of a nation like the US does affects the international capital markets, whether rate-setting or non-traditional quantitative easing, such as QE2, monetary policy and rate-setting is only useful as a trade war weapon. Just witness what's happening to China's economy now, as it tries to maintain a fixed peg.
Here is a still relevant related discussion on central banks over at David Smith's EconomicsUK.