Several years ago, in the course of doing some research on the history of criminal law, I became fascinated by the concept of feud. Feud is a social phenomenon which has been with us probably since men and women first walked upright. It is tied to vengeance and to concepts of family, kin, tribe and nation.

Vengeance, of course, is that emotion human beings feel when they have been wronged in some way. It is, perhaps, best expressed by the biblical concept of “an eye for an eye.” Vengeance embodies the notion that there must be an “equality of hurt,” that if I am injured by you, then I have the right to injure you in a like manner. In this way I may reach some form of psychological closure, feel that the score between us is even.

Vengeance is a harsh concept, but it is one that has pervaded and continues to pervade society. In most countries today, vengeance is illegal if it takes a violent form. Instead, legal systems provide an alternative means to punish those guilty of harming others and of recompensing those injured.

Feud expands on the notion of vengeance. The idea of feud is that if you harm me or one of my friends or relatives, then I not only have the right to seek vengeance against you or your friends or family, but, in fact, I have an obligation to do so. In many cultures, failure to take vengeance in such a context dishonors the individual or individuals who fail to do so.

Thus, feud adds two important dimensions to the idea of vengeance. First, it makes vengeance mandatory, not voluntary. Second, feud expands vengeance from being a personal matter to a group matter. This is, obviously, an extremely dangerous expansion in both respects, since it tends to make vengeance both more frequent and more widespread.

Historically feuds have done enormous damage. We are all familiar, of course, with the classic American feud between the Hatfields and McCoys. But the most extraordinary feuds seem to have been those engaged in by the inhabitants of medieval Iceland. These feuds could last for years and often caused great loss of life. Indeed, during the Middle Ages, Greenland was colonized by the Icelanders and other Scandinavians. Within about a century, however, the population of Greenland was reduced to zero. A number of historians believe that this depopulation of an entire country was caused by long-standing feuds and the violence they caused.

I bring up the subject of feud today not simply for historical interest but because I am coming to believe that in order to understand the tragedy going on in the Middle East now, we must recognize that the battles between the Palestinians and the Israelis involve more than politics or conflict about territory. The terrible conflict between the two parties has been going on so long and has been so intense during the past years that it has come to resemble a feud in many respects. It would appear that neither the rules of international law nor the appeals of other countries for a cease-fire and a just and lasting peace will produce positive results.

In this seemingly hopeless situation, I think that it is important to analyze this conflict in feud terms for several reasons. First, if, indeed, the Palestinian-Israeli conflict has now taken on some aspects of feud, then we must recognize that continuing violence by either side will only make matters worse. Every time one side kills, then the other side must respond. This is precisely the escalation of violence we are seeing on both sides. Any belief that continuing violence will bring an end to the conflict fundamentally misunderstands the peculiar  and deadly  logic of feuds. In the context of a feud, violence simply breeds more violence. One death leads to 20 deaths.

Second, I am afraid that the dynamic of feuds is such that they can rarely be stopped by the parties involved once they have begun. Self-restraint is not a characteristic of feuding parties. Outside intervention, often requiring the threat of force or sanctions, may well be the only way to put an end to the escalating violence.

The conflict in the Middle East is a horrible and gut-wrenching affair, a tragedy of monumental proportions for the Palestinians, the Israelis and the world. There has been so much death and so much destruction that it almost is impossible for outsiders not caught up in the violence to understand. That is very much what feuds are like. If my analysis is correct, then the community of nations cannot waste time. We must stop this feud immediately. Otherwise, future historians may well speculate about the Middle East and the catastrophe that befell it  and the world as a whole  much as present historians speculate on the catastrophe that destroyed Greenland in the Middle Ages.

 Mike Hoeflich is a professor in the Kansas University School of Law.