The guarantor must be able to punish cost-effectively or clients defect.

Evidence

In order to reassure our clients that we can supply credible protection, we also need strength, both physical and psychological. The capacity to command respect, to inspire awe, has frequently been attributed to mafiosi of stature. But above all, mafiosi must be able to resort to violence; the ability to inflict punishment is crucial to the role of guarantor. “Peppe” must be stronger than the parties he protects combined, and both parties must know that in case of “misbehavior,” punishment is a feasible and, for the mafioso, not too costly option. If this were not so, they could simply fight back, protecting themselves effectively from the consequences of whatever action they wished to take. — Diego Gambetta, The Sicilian Mafia The Business of…, 104

Categorization

• XREF: This is the Gunslinger/Schelling credibility condition and the sine qua non of the private-judge/enforcer model — punishment must be feasible and cheap for the enforcer, else the commitment is not credible. Also the exact logic the Godfather names when he says true power is the ability to grant favors and enforce them.