Fear of punishment promotes the emergence of cooperation and enhanced social welfare in social dilemmas

Social punishment has been suggested as a key approach to ensuring high levels of cooperation and norm compliance in one-shot interactions. However, it has been shown that it only works when punishment is highly cost-efficient. On the other hand, signalling retribution hearkens back to medieval sovereignty, insofar as the very word for gallows in French stems from the Latin word for power and serves as a grim symbol of the ruthlessness of high justice. Here we introduce the mechanism of signalling an act of punishment and a special type of defector emerges, one who can recognise this signal and avoid punishment by way of fear. We perform extensive agent-based simulations so as to confirm and expand our understanding of the external factors that influence the success of social punishment. We show that our suggested mechanism serves as a catalyst for cooperation, even when signalling and punishment are very costly. We observe the preventive nature of advertising retributive acts and we contend that the resulting social prosperity is a desirable outcome in the contexts of AI and multi-agent systems. Overall, we suggest that fear acts as an effective stimulus to pro-social behaviour.