01
Cut a thermostat loop
Choose Thermostat & room. The states track each other closely while coupled and spring apart at the cut, each returning to the setpoint it started from. Structure barely moves; viability never wavers.
communicoupling
Cut the loop.
What survives?
Couplings come in grades, and the grade is set by how much of the coupled parties is at stake. A thermostat and a room trade states and stay what they were. A potter and a clay body reshape each other across a working life. A conversation and its speakers make each other: end the talk and no interlocutor is left, only a person who was one.
Ezequiel Di Paolo sorts these into interaction, transaction, and constitution loops. One test separates them. Sever the coupling and ask what still stands: everything, in an interaction loop; the parties, altered and their history frozen, in a transaction loop; nothing that would still answer to those names, in a constitution loop.
coupling strengthhow far each party's state is pulled by the other's
structural plasticityhow readily slow structure follows where the loop holds the state
constitutive dependenceshare of each party's upkeep supplied by the loop itself
loop grade
—
diagnosed from the run after the cut, not from the dials
structure drift
—
share of the parties' opening difference written into their structures
post-cut survival
—
viability held at the end, against its level just before the cut
One run, one cut
gold and blue: the parties' fast states · violet dashed: party A's slow structure · green: viability; coupling drops to zero at the marked line and the run continues
Set the conditions
what to try
Cut the same loop at three grades.
02
Cut a potter's loop
Choose Potter & clay. The violet structure line climbs away from where it began, and the cut leaves it there. The parties keep running, shaped for a partner who is gone, and the drift stops accumulating.
03
Cut a conversation
Choose The conversation. Viability falls toward what each party can produce alone, and the states flatten as the parties lose the dynamics that made them parties.
the mechanism
Three timescales, one severing.
Each party carries a fast state, a slow structure, and a viability. The state relaxes toward that party's own structure and is dragged toward the partner's state in proportion to coupling strength. Structure follows where the coupling keeps putting the state, at a rate set by plasticity and multiplied by the live coupling — so structure records the history of the loop and moves only while the loop runs. Viability tracks supply: a party self-produces the share of its upkeep that dependence leaves it, and draws the remainder through the loop, which delivers only while coupling is live and the partner is still viable. At the marked step the coupling term is set to zero and the run continues under the same equations.
The grade is then read off what happened after the cut. Viability retained below three-fifths of its pre-cut level reads as constitution; otherwise, structure drift held past a small fraction of the parties' opening difference reads as transaction; otherwise interaction. Those cut points are conventions this page imposes on quantities that are continuous. Push dependence up by a few percent near the boundary and the diagnosis flips while the world changes hardly at all.
Two behaviors fall out rather than being written in. Zero plasticity makes drift impossible at any coupling, so the loop can be intense and still leave nothing behind. And deep dependence carried by thin coupling starves both parties before the cut ever arrives — a loop can be constitutive in principle and too weak to constitute anything.
the social payoff
The grade tells you what leaving costs.
Ask of any relationship what its severing would take away, and the answer sorts obligations. An interaction loop can be exited by walking out; the parties resume. A transaction loop leaves marks that outlast it, which is why separation, retirement, and the closing of a long partnership raise a question about what to do with a structure shaped for someone no longer there. A constitution loop cannot be exited by one party, because the party is one of the loop's products: dissolving a marriage dissolves the spouses, dissolving the market dissolves the traders as traders, and the person who walks out afterward is a different party from the one who was in it.
Most disputes about commitment are disputes about the grade. A vendor calls the account a partnership and the buyer treats it as an interaction loop, priced to be switched. A community reads a firm's presence as constitutive while the firm books it as a supply relationship it can cut on notice. Naming the grade in advance, and asking what the cut would cost each side, converts a clash of vocabularies into a question with evidence attached. It also complements structural coupling, which describes how two closed systems shape each other without either instructing the other — this page asks what that shaping puts at stake.
the mapping
Mechanism ↔ social life.
| In the model | In the world |
|---|---|
| fast state | What a party is doing now: the room's temperature, a posture, the current turn of talk. |
| slow structure | What a history writes into a party: skills, habits, expectations, the potter's hands. |
| viability | A party's integrity as the kind of thing it is, which the loop may or may not produce. |
| coupling strength | How much of each party's behaviour the other steers moment to moment. |
| structural plasticity | How open the parties are to being reshaped by their contact. |
| constitutive dependence | The share of a party's existence that the exchange itself supplies. |
| the cut | Separation, exit, layoff, bereavement, the end of the conversation. |
where it tears
Limits.
Most couplings sit on the bottom rung.
Thermostats, APIs, spot purchases, and passing strangers are interaction loops, and they stay that way however intricate the exchange becomes. The grades are a diagnostic ladder with a heavily populated first step. Reading constitution into every coupling turns the scheme into mysticism rather than cybernetics; the default should be interaction until a cut test earns something stronger.
The cut is a thought experiment ethics often forbids running.
The instrument severs the loop for free. Observers rarely can: you would have to end the marriage, close the plant, or dissolve the congregation to see what survives. Evidence therefore comes from cuts that happened by accident — bereavement, exile, layoffs, sudden aphasia — which arrive uncontrolled, unrepeatable, and expensive. Diagnosis in the field is mostly inference from other people's catastrophes.
Grades mix across timescales.
A marriage is an interaction loop by the hour, a transaction loop by the decade, and constitutive of whatever "spouse" names. Asking which grade a coupling has usually means asking over which horizon and under which description of the parties. The model fixes both by choosing a run length and a set of variables, and a different choice would return a different grade for the same relationship.