最後の貸し手機能とインフレーション・ターゲティング

●Robert E. Lucas, Jr., “Mortgages and Monetary Policy”（Wall Street Journal, September 19, 2007）

In the past 50 years, there have been two macroeconomic policy changes in the United States that have really mattered. One of these was the supply-side reduction in marginal tax rates, initiated after Ronald Reagan was elected president in 1980 and continued and extended during the current administration. The other was the advent of "inflation targeting," which is the term I prefer for a monetary policy focused on inflation-control to the exclusion of other objectives. As a result of these changes, steady GDP growth, low unemployment rates and low inflation rates -- once thought to be an impossible combination -- have been a reality in the U.S. for more than 20 years.

Both of these reforms work, in part, because they stabilize people's expectations about aspects of the future. The supply side tax cuts, in contrast to Keynesian on-again-off-again temporary tax cuts, are designed to be in place over the long run, and help to assure us that the returns to today's hard work and savings will not be taxed away tomorrow. Inflation targeting is a commitment that no matter what unpredictable shocks the economy is subjected to, the Fed will do what is needed to restore a fixed, target inflation rate and so maintain a "nominal anchor" to expectations.

This summer's subprime mortgage crisis puts the long-run emphasis of inflation targeting to a severe test. Something has to be done right now. What should it be?

By reducing the discount rate and encouraging use of the discount window -- instead of reducing the funds rate until yesterday -- I think Mr. Bernanke was trying to separate the short-term problem of lender of last resort and the long-term problem of inflation targeting, and to show that we can and will deal forcefully with the liquidity crisis, if one should emerge, without weakening the commitment to price stability.

The need for a lender-of-last-resort function is one qualification to the discipline of inflation targeting, but it is a necessary one. There is a second line of argument that seems to me much less compelling. It starts with the fact that monetary policy necessarily affects future inflation rates, not the current rate: That has already been determined when the open market committee meets. We also know that whatever funds rate target is chosen, all kinds of others forces -- anything that happens to the real economy -- will affect next quarter's rate of inflation, or next year's. So we would like to forecast these other forces as well as possible and take them into account.

There is nothing wrong with this logic, but how useful it is depends on how good we are at forecasting the non-monetary determinants of prices. In fact, inflation forecasting is notoriously one of the squishiest areas of economic statistics. In this situation, it is all too easy for easy money advocates to see a recession coming and rationalize low interest rates. They could be right -- who really knows? -- and in any case we may not know enough to prove them wrong.

To me, inflation targeting at its best is an application of Milton Friedman's maxim that "inflation is always and everywhere a monetary phenomenon," and its corollary that monetary policy should concentrate on the one thing it can do well -- control inflation. It can be hard to keep this in mind in financially chaotic times, but I think it is worth a try.

一年前の論説だけれども、単なる時論にとどまらない（＝状況を超えた普遍性を有する）議論が展開されております。
ルーカス先生は現在の状況をどのように見てらっしゃるんだろうか。