Criminals have great difficulty in trusting each other – they often have conflicting interests (and may sometimes have incentives to inform on each other) but have no very good equivalent of the state to enforce contracts. One traditional solution is to rely on family members, who are presumably more trustworthy.
But there are others – scholars such as Thomas Schelling and Diego Gambetta have speculated that shared information about violent acts might help to cement cooperation. If I know that you have committed a violent act, and you know that I have committed a violent act, we each have information on each other that we might threaten to use if relations go sour (Schelling notes that one of the most valuable rights in business relations is the right to be sued – this is a functional equivalent). Of course, it’s difficult to establish this empirically – as Gambetta notes in his classic book on the Sicilian mafia, active mafiosi make poor interview subjects – at the very best they are likely to be reticent about their activities.
Paolo Campana and Federico Varese have a very nice “new article”:http://federicovarese.com/sites/default/files/2013%20R%26S%20Campana%20Varese.pdf in “Rationality and Society”:http://rss.sagepub.com/ which tests how both traditional sources of trust such as family ties, and less conventional sources such as shared information about violence, might work among real criminals.
bq. This article relies on two unique datasets we have collected on two Mafialike organizations: a Neapolitan Camorra clan based some 50 kilometres north of Naples, and a Russian Mafia group operating in Rome. … Both groups had been under extensive police surveillance, during which investigators were able to monitor all the telephone lines used by the key players, and listen to their conversations. … In both instances we had access to the files prepared by the police for the Prosecutor Office to be used as evidence in court; they include the transcripts of the wiretapped phone conversations. … The network of contacts between the core members of the Neapolitan Camorra clan amounts to 1370 while the core members of the Russian group have exchanged a total of 295 contacts among them.
bq. Kinship does indeed have a statistically significant effect in the Camorra clan: the frequency of contacts between two associates increases when both are near-relatives of the boss. This finding confirms the importance of kinship within this particular Mafia. Extended kinship appears to play a role in the case of the Russian–Italian group. Rather more surprisingly, in both models violence does have an impact on tie formation between two actors. Having shared information about violent acts increases the frequency of contacts occurring among two actors. The ‘violence effect’ is fairly strong, and greater than that recorded for kinship in both cases, including the Camorra. This would suggest that even in clans made of relatives, having discussed violence is a better predictor of cooperation than kinship itself. This further suggests that there is nothing ontological in the role of kinship in organized crime. When better and more reliable mechanisms to increase commitment are available, criminals will use them, just as organizations in advanced societies tend to rely on merit rather than kinship when recruiting employees.
bq. There is additional, non-statistical evidence of the use of violence as a form of credible commitment. The boss of the Camorra clan discussed here would instruct all his men to shoot together at the same time when committing a murder. Everybody in the firing squad had to fire at least one shot. … Each perpetrator is made ‘a hostage’ to all the others, in order to reduce his incentives to defect and/or inform on his fellow associates.