维克霰的利息与物价

(2)维克霰的利息与物价

维克霰(Knut Wicksell)在他的名著《利息与物价》(Interest and Prices)，把这两个因素的关系说得十分明白。他首先想象有一种天然利率(natural rate，or normal rate，or capital rate，of interest)对于物价是中性的(neutral)，不发生何种影响。它的作用，好像没有货币一样。

“There is a certain rate of interest on loans which is neutral in respect to commodity prices，and tends neither to raise nor to lower them.This is necessarily the same as the rate of interest which would be determined by supply and demand if no use were made of money and all lending were effected in the formof real capital goods.It comes to much the same thing to describe it as the current value of the natural rate of interest on capital.”^[64]

他申述货币利率(Money rate，or contractual rate of interest)即实际市场利率，不一定与理想的天然利率相同。如果偶然相同，则借贷之间虽然少不了货币，但其实是与不用货币一样。在此种状况之下，经济平衡既不会发生变动，物价平准即无由发生动摇。

“Now if money is loaned at this same rate of interest，it serves as nothing more than a cloak to cover a procedure which，froma purely formal point of view，could have been carried on equally well without it.The conditions of economic equilibriumare fulfilled in precisely the same manner.In such a case，there is no occasion for any alteration in the level of prices.”^[65]

如果两种利率不一致，譬如货币利率高于或低于天然利率，则其对于物价之影响为何如?维克霰的意见，不是货币的绝对利率的高低，而是货币利率与天然利率相对的高低，发生作用。货币利率比天然利率低，则物价上升;货币利率比天然利率高，则物价下降。一般地说来，天然利率是继续变动的，货币利率是趋向天然利率的，但动作不见得十分敏捷，以致引起物价的涨落。

“An exact coincidence of the two rates of interest is therefore unlikely.For changes in the(average)natural rate may be presumed to be continuous，while themoney rate of interest is usually raised or lowered only in discontinuous jumps of one-half or one per cent，at any rate in so far as it is regulated by the large monetary institutions.But the money rate of interest can lie sometimes above and sometimes below the natural rate，and there is no reason not for expecting a sufficient degree of coincidence to prevent substantial fluctuations in prices.Our problem is，therefore，to show that in these periods when upward movements of prices have been observed，the contractual rate of interest—themoney rate—was low relatively to the neutral rate，and that at times of falling prices it was relatively high.It is only in this relative sense that themoney rate of interest is of significance in regard to movements of prices.It can at once be seen that it is quite useless to try to demonstrate the existence of any direct relation between absolute movements of the rate of interest or of the discount rate andmovements of prices.”.^[66]

“It is thus confidently to be expected that the bank rate，or generally the money rate of interest，will always coincide eventually with natural rate，or rather that it is always tending to coincide with an ever-changing natural rate.But whether the result is achieved with sufficient rapidity to prevent a continual rise in prices at timeswhen the capital rate is rising(so that the money rate is left below the natural rate)，or to obviate a gradual fall in prices when the capital rate is falling(and consequently the money rate is left higher than the natural rate)，seems a priori very doubtful.”^[67]

货币利率为什么不能与天然利率一致行动，维克霰归之于各国银行不能单独变动其政策，必须与其他各国维持协调，结果，不免行动迟缓。公开市场利率虽然比较活动，然决不能追随天然利率之后。所以有时候物价与利率同时涨落，在表面上看去，似乎与理论不合，实则完全相符。

“As regards bank-rate policy，there is a far stronger reason for the maintenance of fixed rules of conduct.For neither an individual bank nor the banks of an individual country can on their own initiative embark on any change without keeping in accord with the procedure adopted by other banks.The openmarketmay perhaps seemto present amore lively picture，but it is practically certain that the lending rate of interest never follows directly on movements of natural rate，and usually follows themonly very slowly and with considerable hesitation.During the period of transition，the deviation between the two rates has full play，resulting in that phenomenon，often referred to above，which on a superficial viewappears to contradict our theory but in reality is in complete accordance with:prices rise when the rate of interest(the capital rate and consequently themoney rate)is high and rising，and in the contrary case they fall.”^[68]

最后他提出一个办法:如物价不变，银行利率可不变;如物价上涨，则应提高利率;如物价下落，则应降低利率。

“This does notmean the banks ought actually to ascertain the natural rate before fixing their own rates of interest.That would，of course，be impracticable and would also be quite unnecessary.For the current level of commodity prices provides a reliable test of the agreement or deviation of the two rates.The procedure should rather be simple as follows:So long as prices remain unaltered，the banks'rate is to remain unaltered.If prices rise，the rate of interest is to be raised;and if prices fall，the rate of interest is to be lowered;and the rate of interest is henceforth to be maintained at the new level until a furthermovementof prices calls for a further change in one direction or the other.”^[69]