The Matthew Principle is; the rich get richer, while the poor get poorer . The sugarscape model of trading sugar and spice leads actors in the game to distribute the wealth unequally. As a pure model it shows how weaker entities in a trading system can be disadvantaged. Yet economic systems through history have not ended up with extreme inequality and then remained in stasis once achieving that point. Obviously society, culture and even violence contribute to cycles of equality. Peter Turchin argues that equality is necessary for cohesive group action. He also argues that social instability in agrarian society acts as a dampening effect against increasing inequality.

Turchin argues inequality has ramification not only between economic strata, but within those strata; and ultimately these lead to a reduction in the ability for the group to act in the larger interest - or asabiya.

... the corrosive effect that glaring inequality has on the willingness of people to cooperate, which in turn underlies the capacity of societies for collective action. The effect of growing inequality is not limited to the escalation of "class warfare" between the poor and rich. Increasing inequality within classes also leads to intense conflict of commoner versus commoner and aristocrat versus aristocrat.

Turchin limits his analysis to agrarian societies. But a recent example of an outbreak of violence that was related to inequality was in Rwanda. While the western media chose to portray the killings as genocide, many of the killings were by Hutu of Hutu. The regions were non-genocidal killings occurred were largely agrarian and had traditions of passing down land to the sons in the family. Due to high population pressures and limited land for dispersal the land that could be given to the sons was not sustainable in size. Older members of farming communities owned up to four times the size of farm than younger members. Much of the violence and killing was against members of the same economic strata who had more land than others.

We may scoff at an inequality ratio of four. But those on the lower end of the scale did not have enough money or land to feed themselves or their families. Because we have chosen the organisational methods of democracy and capitalism, even our poor have the capability for calorific surplus. While Rwanda fell into violence that redistributed power as well as property, Australia is far more socially stable.

Turchin also argues that extreme inequality breeds revolutionary ideologues through the moralistic perception of social injustice and illegitimacy. He uses the example of the thirty years of warfare between the de Guise and Hugenot factions in France during the 14th century.

It is as applicable today with the Middle East. That region has nearly fifty percent of its population under 25. There is soaring unemployment - as high as 60% in Iraq , and there is massive inequality. Not only in the region between the monarchies and autocrats which control the oil wealth, but also with the West who enjoys a higher standard of living than the Middle East.

While the West assumes it is the recipient of the Middle East's rage, Iraq is showing that it is becoming internally focused. Whereas in the Medieval times when land became scarce and nobles too many - violence between nobles and landed gentry usually culled their number sufficiently that land distribution was sustainable once again - oil in the Middle East is not so easily redistributable. It will probably either have to run out, or be routed around with new energy technologies.

Where violence or pestilence in agrarian societies was a form of redistributing wealth by increasing the supply of land and the demand for labor; modern society does not have the same dynamics. The violence coming out of the Middle East will not change the fact that there remain a lot of unemployed youth, wishing for the western lifestyle and repressed by wealthy elites propped up by oil wealth and the West's insatiable demand for their centrally controlled energy crop.

More Reading on Peter turchin

• Peter Turchin
• Asabiya
• Equality
• What Is It Good For
• Edge Effects: Frontier Induced Cohesion
• War and Peace and War and Australia
• The Equality Cycles
• Why No Aboriginal Agrarianism?