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Two years after the Arab revolutions began, the Middle East is more polarized than it has been in modern times — but the divide is no longer between dictators and democrats. Instead, politics in Egypt, Tunisia and Libya has become a battle between secular and Islamic forces, while in Syria, Iraq, Lebanon and the Persian Gulf, Sunni Muslims face off against Shiites.

The common denominator across the region is zero — as in zero-sum games. Even where all sides are nominally committed to democracy, as in Egypt, political movements are more prone to seek the destruction of their rivals than accept the need for compromise and accommodation.