David Andolfattoが、インフレの決定に関する(ニュー)ケインジアン的な見方と(ニュー)マネタリスト的な見方を対比させている


In the extreme version of this view (Woodford's cashless economy), Fed liabilities serve only as a unit of account; and the private sector manufactures the "money" it needs. The Fed determines (influences) the nominal interest rate, which influences the aggregate demand (AD) for goods and services. Inflation is determined in part by the pricing decisions of firms. When AD is strong, prices rise more rapidly; and conversely when AD is weak. Inflation is also determined in part by the Fed's policy function (Taylor rule), which stipulates a long-term inflation target (serving as the nominal anchor) together with the promise to alter the interest rate (hence AD) in response to undesirable movements in inflation away from target.

Conspicuously absent from the theory of inflation above is any role played by the money supply. The Fed's balance sheet plays no role in determining inflation according to this view. It follows as a corollary that the size of the Fed's balance sheet poses no economic risk.



According to this view, there are financial market imperfections (limited commitment, asymmetric information, etc.) that allow Fed and Treasury liabilities to be valued for their liquidity/collateral properties. Inflation, in the long-run at least, is determined by the supply and demand for currency (a special type of Fed liability).

In normal times, currency is dominated in rate of return, so their is a well-defined demand for the stuff. As well, in normal times, reserves are dominated in rate of return, so Fed liabilities are mostly in the form of currency (see first diagram above, prior to 2008). A well-defined demand for currency plus Fed control over the supply of currency means that the Fed can control inflation.

In abnormal times, however, reserves and Treasuries earn (roughly) the same rate of return. In this case, the Fed only controls the total supply of its liabilities--the composition of these liabilities between currency and reserves is determined by banks. Reserves are like a demand deposit liability--convertible into currency on demand. The Fed can influence bank redemption policies by manipulating IOR--if it has this tool available. Note that the Fed has only had this tool available since 2008. (And in light of the political risks outlined above, one could easily imagine Congress taking this tool away.)

If inflation and inflation expectations begin to rise, so should the nominal demand for currency (even if the real demand remains more or less fixed). One might expect a flood of currency into the economy as banks exercise their redemption option on reserves. The flood of currency could potentially validate the higher inflation expectations -- a self-fulfilling prophesy.