After the disputed re-election of the Iranian president Mahmoud Ahmadinejad in June 2009, the clerical regime in Tehran consolidated its grip on power and stifled internal challenges. To the outside world, it appeared that Iran was torn by a conflict between Shiite Islam and democracy.
But last year's unrest and violent crackdown in Iran were actually battles in a larger war that has been raging for centuries within Shiism - a struggle over who should rule the faithful, and how.
Shiite clerics have long debated their role in politics. The "quietist" school - rooted in the sect's tradition of seeking to avoid confrontation with powerful rulers - argues against direct engagement in political matters. The more activist school emphasises the martyrdom of one of Shiism's founding figures, Imam Hussein, who advocated rebellion and confrontation. But even within the activist school, there is a debate over the extent of clerical power.
The model of absolute rule that dominates Iran today is just one of several competing doctrines within the Shiite clergy. Wilayat al Faqih, or "guardianship of the jurist", triumphed under Ayatollah Ruhollah Khomeini, the leader of Iran's 1979 Islamic Revolution. Khomeini's charisma and political skill overshadowed the more moderate vision of Shiism emanating from the Iraqi city of Najaf. By eclipsing the Najaf school, Khomeini succeeded in combining the role of Shiite theologian with that of political leader.
Any long-term change in Iran could be driven by a return to a more traditional interpretation of this concept - one that emphasises rule by consensus, as opposed to an all-powerful leader.
A reinterpretation of Wilayat al Faqih could offer a way out of Iran's crisis: the clergy would keep control over religious and social matters while giving up some political power. There is ample historical and theological precedent in Shiism to justify such a compromise.
In the 7th century, there was a schism within Islam. One camp argued that the Prophet Mohammed's successor, or caliph, should be chosen from among his closest companions. The other camp insisted that any succession must preserve the Prophet's bloodline and, therefore, that his rightful heir was his cousin and son-in-law, Imam Ali.
Shiism emerged as a movement called Shia Ali, or the Partisans of Ali. He was passed over three times in a row for the caliphate, until the year AD 656, when he became the fourth caliph of Islam. In AD 661, Ali was assassinated by a disgruntled follower while praying at a mosque in southern Iraq.
Nineteen years after Ali's death, his son Hussein led a rebellion against the caliph Yazid in Damascus. Yazid's troops besieged Hussein and a small band of supporters near the Iraqi town of Karbala. According to Shiite lore, Hussein and his followers were cut off from the water of the Euphrates River; over 10 days, many starved or died from thirst. The violent deaths of Ali and Hussein gave rise to the Shiite cult of martyrdom, and Shiism assumed the role of a "pious opposition" to the Sunni majority.
In the early 16th century, the Safavid dynasty established Shiism as the state religion in Iran. As most of the Muslim world fell under the Sunni Ottoman Empire, Shiism became identified with Persia. The Safavid rulers of Iran tried to win legitimacy for their rule from Shiite clerics in Iraq and Lebanon.
Until the 19th century, the quietist school of Shiism prevailed: most Shiite clerics steered clear of politics, and Shiites who lived under Ottoman rule in Iraq, Lebanon, and elsewhere did not challenge the dominant Sunni regime. The concept of Wilayat al Faqih dates back to the early 19th century, but Khomeini reinterpreted it in 1970 while he was exiled in Najaf.
In a series of lectures, he grappled with the question of how to create an Islamic state without the Mahdi, the hidden 12th imam whom Shiites regard as infallible and the last rightful successor to the Prophet. Khomeini's innovation was dismissed by other theologians who argued that absolute authority granted to the supreme leader (rahbar in Farsi) goes against the traditional system for choosing a leader in Shiite society. That system requires the consent of the faithful and a consensus among Shiite clerics in choosing the pre-eminent religious leader.
Still, the Islamic Revolution vested Iran with great authority in the Shiite world. Beginning in the 1980s, the Iranian city of Qom eclipsed Najaf as the leading centre of Shiite study, when thousands of Iraqi scholars fled there to escape a crackdown by Saddam Hussein's regime. With Khomeini's vision of the faith ascendant, Shiism came to be viewed in many parts of the world as a violent movement extending from Iran to Lebanon.
After Khomeini's death in 1989 and the selection of Ayatollah Ali Khamenei as his successor, the regime in Tehran continued trying to export the ideals of the revolution. Although some scholars in Qom opposed Khomeini's vision and the authoritarian state, they had to withdraw from public life to avoid a confrontation with the regime.
Emboldened by last year's protests, some dissident clerics spoke out forcefully. One month after the disputed presidential election, Grand Ayatollah Hossein Ali Montazeri issued a religious ruling that did not mention Ayatollah Khamenei by name but declared Iran's leaders no longer fit to rule.
Ayatollah Montazeri reiterated an argument he and other clerics had advanced for years: that an Islamic system of governance must rest on the sovereignty of God as well as the consent of those being governed. "The government will not achieve legitimacy without the support of the people," he wrote.
Ultimately, other clerics are bound to modify Khomeini's vision of an all-powerful leader. Iranians could reach back into Shiite history for the basis of a new political system that remains Islamic and is infused with greater democracy.
Mohamad Bazzi is an adjunct senior fellow at the Council on Foreign Relations and a journalism professor at New York University