What Happens When Two Agree and a Third Suffers?

Contracts are considered the epitome of modern freedom: Two or more parties voluntarily agree on rules, conditions, and obligations. Whether in private law, professional life, or international relations, a contract appears to embody rational autonomy. No one forces, no one is forced. What is negotiated is valid—so goes the theory.

But what happens when a contract doesn’t only affect the involved parties? When there is a third party who was not asked but must bear the consequences? Classical contract theory has no clear answer to this, as it is based on the principle of consensus. What is done in consensus is considered legitimate. But life knows more than consensus partners: It knows those affected, bystanders, and the defenseless. It knows the third parties.

A simple example: Two parents, after separation, agree on a custody model that suits them both. One gains more free time, the other more planning security. Everything seems settled. But the child, the subject of the agreement, was not consulted. Perhaps it wants more time with its father or suffers from constant shifts. The contract is signed—but not fair.

The issue becomes even clearer on a political level: When states sign trade agreements, they may impact ecological resources, indigenous populations, or future generations. Yet, these groups are often excluded. The contract serves the interests of the signatories—but not necessarily the common good.

Even in seemingly voluntary contracts, such as wage negotiations, the inequality is apparent: One offers what they can or want to pay—the other accepts because they hope, must, or stay silent. What looks like an equal exchange often relies on unequal conditions: economic pressure, lack of information, or psychological insecurity. The contract is formed—but who protects those forced to agree?

This reveals a deeper problem: Interests can be legitimate without being fair. And a contract can be voluntarily signed without being ethically valid. The “unknown third party” is not just a legal construct but an ethical figure. It represents all those not at the table but still affected.

Philosopher John Rawls introduced the “veil of ignorance,” a thought experiment closely related to this: Only what one would accept without knowing their societal position can be considered just.

So, anyone signing a contract should ask: What would the third party say? The one I don’t know? The one not yet born? Or the one without a voice?

Perhaps this is the modern expansion of contract thinking: No consensus without empathy. No interests without responsibility. No contract without considering those who couldn’t sign.