The Promise

The volume has anatomized the contract — the enforcement that binds it, the defaults that fill its legal gaps, the incentives that shape the conduct it cannot watch, the relationship that governs what no clause foresaw. Beneath all of it has run a single fact, the one set at the center of this volume: that no contract can foresee everything. Every contract is incomplete, a handful of explicit terms in a sea of silence. The flagship asks the question that incompleteness forces — what fills the gaps the contract leaves? — and finds an answer that overturns what we took a contract to be.

Begin by seeing that the complete contract is not merely hard to write but impossible in principle. To be complete, a contract would have to specify each party's duty in every possible future state of the world — and the states are endless, most unforeseeable even in kind, and even the foreseeable ones beyond counting and beyond the cost of writing down. So no contract is, or could be, complete; every real contract is a skeleton — a few terms for the cases the parties thought likely — standing in a vast silence on everything else. This is not a defect to be drafted away by a more careful lawyer; it is the permanent condition of every agreement, the gap between the finite words the parties can write and the infinite future they cannot foresee. The contract always says less than the parties will need it to say.¹

Yet contracts work — the silence is rarely fatal — and the question is what fills it. Not the document, which says nothing; not, usually, the court, which is rarely asked. What fills the gaps is the unwritten: the parties' trust that each will act in good faith when the unforeseen arrives; the reputation each would forfeit by seizing on a gap to the other's harm; the discretion of whoever holds the authority to decide what no clause addressed. When the contingency the contract never named arrives, the parties consult not the silent text but their understanding of the deal's purpose, the custom of their trade, the relationship they mean to keep, the plain requirements of good faith. The gaps in the written contract are filled, in a word, by the unwritten contract — the tacit understanding, the shared expectation, the trust, that the explicit terms only partly capture and could never wholly replace. This is the volume's answer to its own question: what fills the gaps no clause could close is trust, reputation, and discretion — the things that were never written down.²

Here the inversion turns, and it overturns both the innocent and the cynical view of what a contract is. The innocent view holds that a contract is an expression of trust — a meeting of willing minds, a mutual commitment freely made. The cynic replies that it is the opposite: a substitute for trust, the device that lets us deal with those we do not trust by writing everything down and making it enforceable, so that no goodwill is required — and that the elaborate contract is therefore a monument to suspicion, proof of how little the parties trust each other. But the incompleteness of contracts defeats the cynic as surely as the innocent. For no contract writes everything down; every contract leaves gaps; and the gaps can be filled only by the very trust the contract was supposed to make unnecessary. The most carefully drafted agreement still depends, at its core, on the parties' good faith to handle what no clause foresaw. So the contract does not replace trust — it cannot — it rests on it. The explicit floats on a sea of the implicit; the written presupposes the unwritten; and the trust the contract seemed to banish turns out to be the ground the whole edifice stands on. The contract, the very emblem of the explicit and the enforceable, is at its foundation an act of trust.³

If the contract cannot replace trust, what does it do? A great deal — but less than we imagined, and never alone. It settles the foreseeable: the price, the date, the quantity, removed from dispute by being written. It marks the parties' serious intent, turning a casual word into a committing one and signaling that the matter is grave. It supplies the backstop of enforcement for the gravest breaches, the cases where trust fails utterly and the relationship ends, so that even the untrusting may deal with some security. And it economizes on trust, reducing how much goodwill an exchange demands — but never to zero, for the gaps remain, and the gaps need trust. So the contract is not the opposite of trust but its partner: it carries what can be specified and enforced, and leaves to trust what cannot — and since most of what matters in a long or complex dealing cannot be fully specified, trust carries the larger share, with the contract its junior partner rather than its replacement. This is why, as the handshake plate found, even the most contractual societies run, at bottom, on trust and relationship; and why a people who could trust no one would not be rescued by any quantity of contracts, for the contracts would leave gaps no one could fill.⁴

Now the foundation point, recast in light of the gaps. The contract is the institution that constitutes the market — that makes possible the exchange across time, with strangers, at scale, which the price merely coordinates and the wealth of nations requires. Strip away enforceable contract and the market collapses to the spot barter of the trusting few: no credit, no employment, no investment, no dealing with the distant or the unknown. So the market is built out of contracts. But the contracts are incomplete, and filled by trust; and therefore the market, built out of incomplete contracts, rests not on enforcement alone but on enforcement and trust together — on the sword that binds the explicit terms and on the good faith that fills the gaps between them. The reach of the market is bounded twice over: by the reach of enforcement, where promises can be made binding, and by the reach of trust, where good faith can be relied on to fill what no enforcement reaches. A society poor in either — poor in courts or poor in trust — is poor in market, and poor in the wealth the market brings. This is the deepest reason Douglass North placed institutions at the foundation of economic development: the institutions that enable impersonal exchange must furnish both the enforcement and the conditions for the trust that contracts, being incomplete, will always require.⁵

The picture must be qualified, lest it seem that trust can fill any gap. Sometimes the gaps are too wide for trust or reputation to span — the contingencies too many, the stakes too high, the exposure to a partner's discretion too great — and then no contract, however supplemented by good faith, will serve. This is precisely where, as the volume on the firm showed, the parties stop contracting and integrate: they replace the incomplete contract between separate owners with the single authority of common ownership, where the gaps are filled not by trust, nor by a clause, but by the residual control of the owner, who simply decides what the contract did not. The firm and the contract are thus twin answers to the one problem of incompleteness: the contract fills its gaps with trust and good faith, and governs where those suffice; the firm fills its gaps with authority, and takes over where they do not. The make-or-buy boundary, seen from here, is the line between the gaps that trust can fill and the gaps that only authority can — between the incompleteness a relationship can bear and the incompleteness that requires a boss. So the two institutions of this family so far, the firm and the contract, divide the world of incomplete agreements between them: where trust will stretch, we contract; where it will not, we command.⁶

The contract has, besides its economic work, a place in the moral architecture of a free society, and it is worth naming as the family takes shape. The firm replaces the market where the price is too costly; the contract constitutes the market, making the priced exchange possible at all — and proves, in its incompleteness, that the market rests on trust as much as on enforcement. But the contract is also the institution of freedom. Henry Maine saw that the movement of progressive societies has been a movement from status to contract — from a world in which a person's obligations were fixed by birth and station, the duties of caste and rank one did not choose, to a world in which one's obligations are those one has freely undertaken. To be bound by contract rather than by status is to be bound only by what one has agreed to; and the contract is the legal form of the free choice that the whole table assumes — the wage freely struck, the loan freely given, the chooser of the behaviors family acting, in the marketplace, by binding himself through his own promise. The rise of the contract is, in this sense, the rise of the chooser: the replacement of the obligations one is born to by the obligations one elects.⁷

The contract, then, is the foundation the market stands on — and its deepest lesson is that the foundation is not solid all the way down. The contract turns the bare promise into a binding one, and so builds the market that the price coordinates; but the promise it binds is always incomplete, and the gaps are filled by the trust, reputation, and discretion that no clause can capture and no court supply. The explicit rests on the implicit; the market rests on enforcement and trust together; and the wholly specified, trust-free economy is a thing that cannot be built, for the contract that would build it cannot be written. But the contract, having laid the second course of the institutional scaffolding, names the courses still to come. The promises it binds must be reckoned in something — in money, the measure and store of the value traded across time, the next institution. Its enforcement of last resort must be provided by something — by the law, and behind the law the state, whose power the rule will examine. And the enforcing, and the public goods that the commons could not supply, must be paid for by something — by the tax. A promise must be counted, a promise must be enforced, and the enforcing must be funded: money, tax, and rule are the institutions the contract calls for, and the family's work to come. The market is built out of contracts; the contracts are built out of trust and enforcement; and the enforcement, in the end, rests on the rule and is paid for by the tax, in a coin the money supplies. We have laid the second course now — and found, at the heart of the institution of the explicit, the unwritten trust that no institution can replace.⁸