In February, reports of violent mobs, which had previously made headlines in Philadelphia and Chicago, began to appear in New York City. With these new accounts of theft and beatings, the once benign term "flash mob" has taken on a more insidious connotation.

Christian Borch, in "The Politics of Crowds: An Alternative History of Sociology," encourages his fellow sociologists --- as well as police officers --- to take the destructive behavior of some participants into account when dealing with groups of rioters.

"The notion from the 1960s that social movements happen as a legitimate response to social injustice created the impression of riots as being rational," Borch said. "Crowds however do not have to be rational entities." Borch argues that seeing participants of group riots as rational individuals driven by a sense of injustice is a misleading assumption these days.

In his book published last year by Cambridge University Press, he follows the development of the concept of crowds from a sociological context. Borch traces sociological debates on crowds and masses from the birth of sociology until today, with a particular focus on developments in France, Germany and the United States.

Analyzing the so-called 'UK Riots' in the summer of 2011, Borch describes how young people set the streets of London alight and looted shopping centers, yet the police adopted an initial strategy of communicating with the rioters who were perceived as discontent. This tactic failed, though, and eventually the force resorted to using batons and containment.

"The riots in London demonstrate the existence of a lack of rational thought processes as the events had an entirely spontaneous and irrational character," says Borch. "People looted for the sake of looting, for many this was not necessarily born out of a sense of injustice."

Borch also took into consideration a Danish example: the violent reactions to the clearance of 'Ungdomshuset' in 2007. In that instance, the "Youth House" functioned as a venue for music as well as a rendezvous point for leftist groups and others from 1982 until 2007, when it was torn down after prolonged conflict. The revolts developed into serious criminal actions.

"During the Danish riots there existed on the one hand a sense of rationality within the young people's protests, in so far as they were driven by a political motivated interest. However, other people who were normally not affiliated with 'Ungdomshuset' became a part of the conflict and participated in the riots without any shared purpose. They were having fun and the adrenalin kicked in," says Christian Borch.

Demonstrations are capable of creating a self-perpetuating sense of dynamics which accentuate the irrational elements. Thus, setting cars alight and breaking windows became part of the rioting. Inner group dynamics fuel pointless behavior.

Regarding the London riots, Borch stated, "The rational way of regarding the crowds came to nothing whereas the traditional form of containment did. This shows that at certain times a successful solution is not to handle crowds based on dialogue-orientated efforts."

In addition to the police, Borch encourages town planners, sociologists and economists to apply a more critical approach when dealing with the concept of crowds.