Why the second signature on a petition matters most

A single name on a petition is a person with a complaint. A second name changes the object: there is now a shared position rather than an individual grievance. The tenth signature adds far less than the second did, and organisers who have run both know which one is hard to get.

What everyone sees

Support is imagined as additive, each name contributing an equal increment. Under that model the difference between one and two should be no larger than between eleven and twelve. Organisers report otherwise, and attribute it to momentum — a description rather than a mechanism.

What is actually happening

Asch’s conformity experiments found that a single ally reduced conformity to a majority dramatically, far more than any subsequent addition. Latané and Wolf’s social impact theory predicts exactly this diminishing pattern: the marginal effect of each additional source falls with the number already present. The first dissenter is deviant by definition; the second converts deviance into a minority position, which is a category others can join.

Why it stays hidden

The non-linearity hides because counts are reported and thresholds are not. A petition displays a total, so the structural change between one and two is invisible in the only number anyone sees. Failed attempts are also unrecorded: the campaigns that never reached a second signature leave nothing behind, so the visible population consists entirely of cases that cleared the threshold.