§4. Real and Money Interest

The theoretical relation existing between interest and appreciation implies, then, that the rate of interest is always relative to the standard in which it is expressed. The fact that interest expressed in money is high, say 15 per cent, might conceivably indicate merely that general prices are expected to rise (i.e., money depreciate) Edition: current; Page: [42] at the rate of 10 per cent, and that the rate of interest expressed in terms of goods is not high, but only about 5 per cent.

We thus need to distinguish between interest expressed in terms of money and interest expressed in terms of other goods. But no two forms of goods can be expected to maintain an absolutely constant price ratio toward each other. There are, therefore, theoretically just as many rates of interest expressed in terms of goods as there are kinds of goods diverging from one another in value.

Is there, then, no absolute standard of value in terms of which real interest should be expressed? Real income, a composite of consumption goods and services, in other words, a cost of living index in accordance with the principles set forth in Chapter I, affords a practical objective standard. By means of such an index number we may translate the nominal, or money rate of interest, into a goods rate or real rate of interest, just as we translate money wages into real wages. The cost of living plays the same rôle in both cases although the process of translating is somewhat different and more complicated in the case of interest from what it is in the case of wages, for the reason that interest involves two points of time, instead of only one; so that we must translate from money into goods not only in the present, when the money is borrowed, but also in the future, when it is repaid.

Income is the most fundamental factor in our economic lives. The derivation of the value of every durable agent or good involves the discounting or capitalizing of income as one of the steps. Consequently, a rate of interest in terms of fundamental income itself would seem to come as Edition: current; Page: [43] near as we can practically come to any basic standard in which to express a real rate of interest.

But, in actual practice, it is the rate in terms of money with which business men deal and hereafter the rate of interest, unless otherwise specified, will in this book be taken to mean this money rate.

The money rate and the real rate are normally identical; that is, they will, as has been said, be the same when the purchasing power of the dollar in terms of the cost of living is constant or stable. When the cost of living is not stable, the rate of interest takes the appreciation and depreciation into account to some extent, but only slightly and, in general, indirectly. That is, when prices are rising, the rate of interest tends to be high but not so high as it should be to compensate for the rise; and when prices are falling, the rate of interest tends to be low, but not so low as it should be to compensate for the fall.21

The principle of interest being relative to the standard used in loan contracts would be more in evidence if it were customary to make loan contracts in terms of other standards than money. The rate is actually expressed in loan contracts in terms of money and only translated into terms of goods, if at all, after the contract has been fulfilled, when it is too late to stipulate compensations for the rise or fall in monetary value. If the money rate of interest were perfectly adjusted to changes in the purchasing power of money—which means, in effect, if those changes were perfectly and universally foreseen— Edition: current; Page: [44] the relation of the rate of interest to those changes would have no practical importance but only a theoretical importance. As matters are, however, in view of almost universal lack of foresight, the relation has greater practical than theoretical importance. The business man supposes he makes his contracts in a certain rate of interest, only to wake up later and find that, in terms of real goods, the rate is quite different.

The real rate of interest in the United States from March to April, 1917, fell below minus 70 per cent! In Germany at the height of inflation, August to September, 1923, the real rate of interest fell to the absurd level of minus 99.9 per cent, which means that lenders lost all interest and nearly all their capital as well; and then suddenly prices were deflated and the real interest rate jumped to plus 100 per cent.22

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