Criminals use nicknames both to separate insiders from outsiders and to stymie potential investigations into their activities (which is itself a form of stonewalling outsiders). They use violence strategically rather than randomly, and prefer to send hard-to-fake signals about their badness and their inability to fit in any part of the larger world: hence the tendency toward showing incompetence at tasks other than criminality, as seen on The Sopranos, the tendency toward extreme tattoos, and the tendency toward group participation in criminal events. The last binds the participants together. You can see some of the same behavior in almost any group of people; for example, a group of teenagers might decide they’re poor math students, they like to wear black, and they prefer to smoke weed with one another, the last being necessary to ensure group culpability—”they try to force each other to participate and torment or ostracize those who refuse.”

This comes from Codes of the Underworld, a clever book that is actually about signaling, semiotics, and economics more than any other subjects, despite my introduction. Its conclusions feel obvious after reading, but I doubt I could’ve articulated them prior. It has an impressive range of detailed examples supporting its general observations.

For example, criminals are good at finding liminal spaces where criminality might be implied, but not completely; Gambetta cites drivers who would nominally “forget” cash when handing over their license to police:

A quick-witted and corrupt policeman could choose to pocket the banknote (or bargain for more); if not corrupt, he was unable to treat the display of the ostensibly “forgotten” banknote as sufficient evidence of attempted bribery.

Steven Pinker makes similar claims about linguistic issues in The Stuff of Thought, where he describes the verbal tango people in crimes, love affairs, and other situations undergo. In both crime and love affairs, very good reasons often exist for evading overt, blunt language: being caught by police in the former and being unambiguously rejected in the latter.

As the above issue regarding bribes perhaps shows, criminals are more rational than they’re often made out to be: “Far from being driven by a feudal or monarchic mentality, mafiosi display a surprisingly modern mind-set in managing their organization, at odds with much of the Italian nepotistic and corrupt style.” I like the sentence itself as well as the thought behind it: the sentence compacts a lot of material into a short space (“monarchic mentality,” “Italian nepotistic”), which alludes to allegedly common knowledge while also correcting that knowledge. Some parts are wonderfully academic in their obtuse cleverness, as when Gambetta says, “This sort of usage seems a jocular custom, a form of bantering, and it would be a stretch to attribute it to an instrumental motive.” In other words, friends sometimes greet each other affectionately and informally. But those moments are few, especially relative to the easy density in Codes of the Underworld and the fact that it also nearly functions “semiotics for dummies,” with a fair amount of the theory one might otherwise find in Umberto Eco or Roland Barthes. In short, it’s multidisciplinary and academic in the best sense of both words.

A blurb from Thomas Schelling on the back says that “[…] the book’s interpretations will carry well beyond the field of conventional crime.” He’s right, and one major strength is that, as with the best nonfiction books, Gambetta uses a particular field or example from a particular field (in this case, criminality) to comment simultaneously on a much larger issue (how people communicate and form social bonds) without straining too far to either side, which would destroy the whole.

(Here is Tyler Cowen’s take, or rather citation. I don’t know of any other interesting posts about the books.)