Research

The three papers that comprise my PhD thesis focus on the informal enforcement of social norms. 

Chapter 1: Reputation on Networks

This paper presents a network model of reputation. The model investigates how a reputation system can regulate opportunism and facilitate trust in low-frequency or one-off transactions beyond an agent's immediate network. The setup focuses on how the network facilitates access to transaction opportunities and determines the distribution of reputational information. When agents leverage trust over multiple homogeneously distributed transactions, the network structure determines a trust ranking of transactions between any two individuals. By incorporating how the salience of an agent's reputation affects who gets informed, the model identifies a unique set of gatekeeper agents that can regulate the flow of information. These gatekeepers may receive limited trust but can facilitate trust between their links. The model provides a flexible framework that is tractable on a general network. Extending this framework by relaxing various assumptions, the model can investigate several interesting questions. In particular understanding the connection between local and generalised trust, patterns of informal sanctioning and coordination on in-group vs out-group norms.

Link to paper: Reputation on Networks 

Chapter 2: Reputation, Punishment and the Informal Enforcement of Norms

This paper introduces a model of informal enforcement that integrates both reputational punishment and costly social punishment, highlighting their complementary roles in sustaining cooperation. The model reveals that social punishment is often necessary to support a reputation system and that punishment without reputation is unlikely to yield positive payoffs to the punisher. Once cooperation is established, the two enforcement mechanisms act as substitutes, with the equilibrium level of social punishment decreasing as the power of reputation to enforce cooperation grows. The model is applied to norm enforcement by examining the regulation of two broad categories of behaviour, Leveraged behaviours, which are 'trust-like' in that cooperation yields a net benefit, and Costly behaviours, which are like public good contribution in that compliance results in a net cost. The findings suggest that understanding the nature and intensity of informal sanctions requires considering the array of enforced behaviours within a community rather than focusing solely on the enforcement of a single norm. By considering how other factors, such as culture, development and institutions, affect reputation systems by  changing the nature and distribution of transactions, the paper contributes to understanding the variation in norm enforcement across societies and the impact of these factors on economic success.

Link to paper:  Reputation Punishment and the Informal Enforcement of Norms 

Chapter 3: Ingroup Norms and Relation Specific Punishment

This paper presents a model investigating ingroup favouritism and inter-group cooperation. While many existing models emphasise the role of information limitations, here, variation is driven by how patterns of interaction determine ingroup agents' incentives to punish other members for defecting outside the group. When agents are embedded in a reputation system, incentives for punishment arise indirectly. Committing to punish fellow ingroup members, means outsiders can trust them more, in effect increasing the value of their reputations. In turn, outsiders value ingroup relationships more, so they can also be trusted more by ingroup agents, including the punisher. Payoffs to punishment depend on the inter-group interaction frequency, transaction profitability, and the value of new transactions that increased trust facilitates with the outgroup. The model provides a mechanism which can be applied to understand how economic context impacts patterns of trust, cooperation and social punishment across different communities.

Link to paper:    Ingroup Norms and Relation Specific Punishment 

Working Papers:

Systems of Violence and Reputation

Public Good Provision in Informal Networks

Truthful Reporting, Gatekeepers and the Limits of Reputation