# Spontaneous cooperation for public goods

## TL;DR

This paper demonstrates that spontaneous cooperation in public goods can emerge from simple local conformity dynamics influenced by noise, without the need for rational incentives or monitoring.

## Contribution

It introduces an Ising model-based explanation for how random noise can trigger cascades of cooperation in public goods dilemmas.

## Key findings

- Cooperation can spontaneously emerge at a critical noise level.
- An analytic relationship links phase transition to asymmetry in cooperation and defection.
- Random noise alone can resolve the cooperation dilemma without rational decision-making.

## Abstract

Cooperation for public goods poses a dilemma, where individuals are tempted to free ride on others' contributions. Classic solutions involve monitoring, reputation maintenance and costly incentives, but there are important collective actions based on simple and cheap cues only, for example unplanned protests and revolts. This can be explained by an Ising model with the assumption that individuals in uncertain situations tend to conform to the local majority in their network. Among initial defectors, noise such as rumors or opponents' provocations causes some of them to cooperate accidentally. At a critical level of noise, these cooperators trigger a cascade of cooperation. We find an analytic relationship between the phase transition and the asymmetry of the Ising model, which in turn reflects the asymmetry of cooperation and defection. This study thereby shows that in principle, the dilemma of cooperation can be solved by nothing more than a portion of random noise, without rational decision making.