The Zero

The price of time seems to reach its natural end at nothing: lend a hundred, receive a hundred, and neither patience nor borrowing commands a fee. Yet a zero rate can coexist with expensive credit, profitable investment, and an economy in which too little is spent. The nothing belongs to a particular contract, measured in a particular money, over a particular interval. It says nothing by itself about the return after prices change, the borrower's chance of default, or the cost of turning a factory back into cash. The distinction matters most when the central bank has cut its short rate almost as far as it can and employment remains weak. At that point zero may be less a gift to the borrower than a barrier to the recovery: the money rate has stopped falling before the real rate has fallen far enough. This plate follows the rate to that barrier, asks why the barrier can sit below zero, and considers what becomes of the reward for waiting when a safe promise returns fewer monetary units than it received. The question is no longer simply how much patience earns. It is what the monetary system permits the price of patience to become.

Cash supplies the familiar reason for a floor beneath the nominal rate. A banknote pays no interest, but the number printed on it does not diminish merely because its holder waits. If a deposit returned ninety-nine for every hundred and notes could be held without cost or inconvenience, the depositor would have an obvious alternative. Actual possession is less obliging. Notes must be stored, guarded, insured and carried; large payments are easier through accounts than through the movement of paper. A slightly negative account rate can therefore buy something worth having: secure custody and the means of settlement. The relevant comparison is between the whole service supplied by each way of holding money, including its costs. This makes the floor an effective lower bound, dependent on the institutions of payment and storage, rather than a mathematical prohibition at precisely zero.¹ Nor is it the same boundary for every holder. A household keeping a small reserve of notes faces a different practical choice from a bank settling payments or an institution holding a large portfolio. Crossing zero does not abolish the outside option; it begins to test how attractive that option really is.

The binding constraint is nominal, while the decision to spend reaches through money to goods. Suppose, solely to make the arithmetic visible, that the price of a fixed basket will certainly fall from one hundred to ninety-eight over a year. Money held at zero interest then buys about 2.04 per cent more of that basket at the end. The nominal return is nothing; the real return is positive. A firm comparing a new investment with a safe financial asset must reckon with that alternative, while a household expecting weaker income may wish to save still more. In Krugman's account of the liquidity trap, a short safe bond and money become such close substitutes that exchanging one for the other need not induce additional expenditure. With prices unable to adjust immediately, production and employment can bear the adjustment instead.² This is a conditional account of a failure of demand, not a claim that every zero rate announces a depression. It also leaves room for positive returns on productive projects: their risk, their illiquidity and their changing resale value distinguish them from the safe short claim. Nothing in the rate on that claim requires every machine, every loan and every year of waiting to earn nothing too.

Secular stagnation gives the difficulty a longer horizon: desired saving and investment may balance at full employment only at a persistently low or negative real rate. The qualification at full employment does the work. Actual saving and investment remain joined by the accounts; an unfulfilled wish to save more can be reconciled with weak investment by a fall in income, leaving the economy smaller than it could have been. In the overlapping-generations model of Eggertsson, Mehrotra and Robbins, demographic change, borrowing constraints and the opportunities for investment can keep the natural rate low without an automatic return to the earlier state. If inflation is insufficient to place the required nominal rate above its floor, nominal rigidities can sustain deficient demand.³ The model supplies a possibility and mechanisms, not a timeless announcement that the world has exhausted its productive future. An economy may need homes, infrastructure and discoveries while private expenditure on them remains inadequate at the prevailing terms. A need is not yet a financed project; a valuable project is not necessarily an asset a cautious saver can hold. The low safe rate can expose that distance. Calling it stagnation identifies a problem of coordination across time, whose causes must be established before its cure can be chosen.

The lower bound changes the channels of policy without making all policy powerless. A promise about future short rates can influence the cost of borrowing for longer; purchases of longer assets can alter the risks and securities private investors must hold. These operations work through expectations and portfolios, which gives their credibility and design a place that a simple instruction to increase the quantity of money cannot fill. Krugman's argument turns on what the public expects to happen after the immediate difficulty has passed: an expansion understood to be temporary can leave the trap intact. The central bank must also consider what its promises will mean when circumstances change. Public spending, taxation and investment can address expenditure through other channels, with effects that depend on financing, capacity and the households affected. There is no single escape formula hidden behind the zero. A more literal crossing occurred in June 2014, when the European Central Bank announced a deposit-facility rate of minus 0.10 per cent, effective on the eleventh of that month.⁴ The charge applied to specified balances at the Eurosystem, including excess reserves. It did not decree that every household deposit, every mortgage or every private loan must carry a negative rate. The passage below nothing was an institutional decision transmitted through a financial system, rather than a universal change in the price of every tomorrow.

The distribution of a rate cut is more complicated than a transfer from the virtuous saver to the fortunate debtor. A household seeking new interest income may lose, while the holder of an existing fixed payment may gain from its higher market value. A borrower can benefit if the cost of servicing or refinancing debt falls; a worker can benefit if stronger expenditure sustains employment. These are different positions, sometimes occupied by the same person, and their balance cannot be read from the sign of one rate. Banks bring another complication. When yields on their assets fall but the cost of deposits is difficult to reduce, margins can narrow; better repayment by borrowers and gains on existing securities may offset part of the pressure. Whether a further cut supports credit therefore depends on balance sheets, funding and the wider economy.⁵ The legitimate question is what the policy accomplishes and who bears its costs. A loss of interest income deserves to be counted, but counting it does not settle the effects on income, employment or wealth. Nor does an intended recovery excuse ignoring the losses. The assessment requires a comparison with the economy that would otherwise have followed, not with a promised world in which all savers receive high safe yields and all borrowers finance worthwhile projects cheaply.

At the floor, the rate loses its easy claim to be the natural wage of a single virtue. A negative nominal yield need not mean that everyone prefers the future, that capital has ceased to produce, or that waiting has become painless. It can be the price of safety and settlement, shaped by inflation expectations, the scarcity of acceptable assets and the policy chosen for an economy short of expenditure. That explanation neither condemns nor vindicates the price; it tells us what must be investigated before judgment. Patience remains a real act, but the safe return to it is not guaranteed by the act itself. And a society's obligations to its future cannot be taken from the sign of a short financial contract. The next plate will ask what rate should govern that larger reckoning. Here the lesson is narrower and more unsettling: zero does not remove time from economic life. It reveals how much of time's apparent price depends on the forms in which a claim on the future can be held.