To answer the question of why we seek justice and revenge, we first need to understand the evolution of the tendency in humans to form cooperative coalitions. This is because it’s this phenomenon only that gives rise to contexts in which we seek justice and revenge.So why do we form cooperative coalitions at all?Why do people come together and work together?The fundamental condition to be met for the formation of a cooperative coalition is that there must be some common goals that the coalition is trying to achieve. The attainment of these goals must benefit each member of the coalition in some way. If a member of a coalition feels that the goals of his coalition are not in line with his own goals then obviously he will decide to break free from the coalition.In short, it’s the gains that motivate people to form coalitions and stay in them.Ancient coalitionsIn our ancestral times, forming cooperative coalitions helped our ancestors to hunt large animals, share food, invade territories, build shelters and defend themselves better. Those who formed coalitions had an evolutionary advantage over those who didn’t.Hence, those possessing the psychological mechanism of coalition formation out-reproduced those who didn’t. The result being that more and more members of the population were willing to form cooperative coalitions.Today the people who desire to form coalitions far outnumber those do not possess any such desire to the point ‘forming alliances’ is considered by many as the fundamental attribute of human nature. The point is that the psychological mechanism of forming coalitions has made its way into our psyche because it had myriad benefits.But the full story about coalition formation in humans isn’t so simple and rosy…Justice, punishment, and revengeWhat if some members of a coalition are defectors and free riders i.e. they take away only the benefits without contributing anything or even incurring huge losses to other members of the group?Such members will have a huge fitness advantage over those who’re loyal to the coalition. Also, when huge costs are incurred over other members they’d doubtless want to break free from the coalition, and the coalition will get torn apart.So the presence of defectors and free riders will work against the evolution of the psychological tendency to form cooperative alliances. If such a tendency has to evolve, there must some opposing force that keeps defectors and free riders in check.This opposing force is the human psychological desire for justice, punishment, and revenge.
The desire to punish those who’re disloyal toward the coalition helps keep disloyalty in check which in turn facilitates the evolution of the tendency to form cooperative coalitions.We frequently witness the human desire for justice, punishment and revenge not only throughout history but also in our day to day lives. When strict punishments are in place for those who fail to contribute their fair share, high levels of cooperation tend to emerge. Add to this the desire to harm slackers and those who’ve incurred a heavy cost on others. This, in common language, is called revenge. Studies have shown that people’s reward centres of the brain are activated when they punish or observe punishment of those who they think deserve punishment. Revenge is indeed sweet.