Böhm-Bawerk defines the rate of interest as the ratio of intertemporal goods prices, but cannot show the emergence of interest as a financial market price. The alleged efficiency ofroundabout production methods is ill-suited to derive a uniform rate of return of capital. Time preference may affect the allocation of income flows and the decision to build up individual wealth, but credit supply follows from a portfolio decision on the structure of the stock of assets. Here, liquidity preference and monetary policy operations have a decisive influence, whereas changes of productivity and time preference are poor predictors of even the sign of market interest changes. A 'natural' rate of interest, determined by 'deep' parameters of capital, production and time, does not exist; it turns out to be a mere estimated value of the bank rate, as a proxy for goods market equilibrium conditions.
interest rate theory capital goods and capital value time preference liquidity preference