Toughness is a quality lacking in subtlety, for one either has it or does not. There is no coming in second best, only winning or losing. While the quality of most commodities is distributed over a continuous scale with products at every level, the ability to resort successfully to violence functions as a dichotomous variable: that is, within any given context one and only one supplier has what it takes, and if buyers cannot count on his services, they can never feel safe. Thus we see an additional reason why the protection market is monopolistic.

DEFINE: Clarifies why the protection market is naturally monopolistic rather than graded like typical commodities.

Diego Gambetta, The Sicilian Mafia The Busi…, loc. 105