Plate iii in print

The Excess

economic rent generalized: the payment to any factor above the least that would keep it in its use — the surplus that does no work.

Rent is whatever a factor is paid above the least that would keep it where it is — the part of its earnings that calls forth no effort, attracts no new supply, and could be taken without its going anywhere.

— the generalization of this plate, after Alfred Marshall, 1890

Ricardo's rent was a fact about land, bound to the soil and to the special circumstance of fields that differ in fertility. The decisive step in the theory of rent — taken late in the nineteenth century, and most clearly by Alfred Marshall — was to notice that nothing in Ricardo's argument actually depended on land at all. The same structure could be lifted off the field and set down anywhere; and once economists knew its shape, they began to find it beneath a startling range of ordinary incomes.

The generalization runs through a single clarifying distinction. Any factor of production — a worker, a machine, a plot, a talent — earns some income in its present use. Part of that income is necessary: it is the least the factor must be paid to keep it where it is rather than let it move to its next-best use. Marshall called this minimum the factor's transfer earnings; it is simply its opportunity cost, the value of its best alternative. The rest of the income — anything paid above the transfer earnings — is economic rent. Rent is the excess: the part of a payment that exceeds what was needed to summon the factor into its use at all.1

1. Alfred Marshall, Principles of Economics (1890), drew the distinction between transfer earnings — the minimum needed to keep a factor in its use, its opportunity cost — and rent, the surplus above that. Pareto reached a similar generalization, and J.S. Mill had glimpsed it earlier in treating exceptional talents as "natural monopolies."

The importance of the distinction lies in a property that sounds merely technical and is in fact explosive. Transfer earnings do real economic work: they must be paid, or the factor departs, so they govern where factors go. Rent does no such work. By definition it is the surplus over what was necessary; the factor would do exactly what it does even if the rent were stripped from it, because it would still be receiving at least its transfer earnings. Rent, then, has no allocative function at the margin — it is a payment that changes no behavior, calls forth no additional supply, and could in principle be removed, by tax or competition or bargaining, without altering what anyone does. It is pure surplus to the owner of the scarce factor, and, in the economist's exact sense, idle.2

2. Rent has no incentive or allocative function at the margin: because it is the payment above what is needed to keep the factor in place, it can be removed without changing supply or allocation. This property — that pure rent is "idle" — is the foundation of the single-tax argument of the fifth plate.
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Once rent is defined this way, the examples leap out, and most have nothing to do with land. Consider a singer of rare and irreplaceable voice who earns ten million a year. What are her transfer earnings — the least she would accept to go on singing rather than take her next-best occupation? Perhaps a small fraction of that sum. The vast remainder is rent: a surplus she collects not because it is needed to make her sing, but because her gift is scarce and cannot be reproduced to compete the surplus away. The same holds of the prime corner lot, the patent on a needed medicine, the mineral seam, the athlete, the surgeon with the singular hand. Each earns a rent in exact proportion to the scarcity of what it offers and the impossibility of supplying more.3

3. The rent of rare talent: the great performer, athlete, or specialist earns mostly rent, since transfer earnings are low relative to the payment scarcity commands. This is Mill's "natural monopoly" of exceptional gifts — Ricardo's argument about scarce land, applied to scarce persons and things.

Whether a given payment is rent depends, crucially, on the horizon over which one looks, because it depends on whether supply can grow. In the short run almost everything is fixed — the factory already built, the skill already learned, the doctors already trained — and earns a surplus that is, for the moment, rent. In the longer run supply may expand: more factories are raised, more workers trained, and the surplus is competed away. Marshall gave this temporary surplus a name of its own, quasi-rent — the rent earned by something fixed for now but not forever, melting as the supply it commanded a premium over slowly arrives. So rent is not a fixed compartment of income but a matter of degree, set by how inelastic the supply of a factor is over the period that concerns us. The more permanent the scarcity, the more durable the rent; pure rent, in the strict sense, belongs to what can never be multiplied at all.4

4. Marshall's quasi-rent: the return to a temporarily fixed factor, eroded as supply expands. Rent is thus a matter of degree, set by supply elasticity and time horizon. The fourth plate, The Quasi, follows the blurring of rent into profit that this implies.

The real power of the generalized concept is that it becomes a question one can put to any income whatever: how much of this payment is transfer earnings — necessary to summon the factor — and how much is pure rent, a surplus to scarce ownership that does no economic work? Asked of a wage, the question separates the part that pays for the worker's effort and skill from the part collected because the worker, or his position, is hard to replace. Asked of a profit or an interest payment, it separates the reward for a genuine service from the toll of a protected position. It is, in this sense, a solvent — a way of dissolving any income into its working and its idle parts, and of seeing how much of what is paid is paid for nothing done.5

5. Rent as a diagnostic put to any income: the transfer-earnings and rent split applies to wages, profits, and interest alike, separating the payment that does economic work from the idle surplus. The founding volume's "power" component of a wage is, in this language, precisely a rent.

And here the dry definition reveals the charge it has carried for a century and a half, which the rest of the volume will be unable to set down. If a large part of some incomes is rent — surplus over what the recipients would need to do exactly what they do — then a great deal of the distribution of income is, in the strict efficiency sense, arbitrary: it could be redistributed without anyone working or producing less, because the part that is rent was never doing economic work to begin with. The claim is not that such redistribution is wise or just; those are further questions. It is that the standard objection to it — that it must blunt incentives and shrink the pie — simply does not reach the rent component, by the very definition of rent. This is why a concept as bloodless as economic rent has been, for a hundred and fifty years, among the most politically charged the discipline owns.6

6. The corollary of redistribution without efficiency loss: the rent component of an income can in principle be taxed or redistributed without blunting incentives, by definition, since it does no allocative work. This is a positive claim about efficiency, distinct from the normative question of whether such redistribution is desirable — and it is the source of the concept's long political charge.

Rent, freed from the land, is the name for the surplus that scarcity hands to ownership and that does no work to earn. Two questions follow at once, and the next two plates take them in turn. If rent is idle surplus, the oldest response to it is moral and fiscal: take it. And if rent is a prize that scarcity throws off, a darker possibility waits — that scarcity, and the rents it yields, can be manufactured on purpose by those who mean to collect them.