Two pilots who are flying an airplane together start punching each other in the cockpit. One ejects those members of the crew whom he believes to be close to his rival; the other screams that his copilot isn’t a pilot at all, but a thief. At that moment, the plane spins out of control and swiftly loses height, while the passengers look on in panic.

These are lines from a recent newspaper column by Can Dündar, a Turkish journalist, and I can think of no clearer aid to understanding the perverse, avoidable, almost cartoonish confrontation that has engulfed Turkey since last December, and that threatens to undo the political and economic gains of the past decade.

The parties to the confrontation are the prime minister, sixty-year-old Recep Tayyip Erdoğan, and a Turkish divine, Fethullah Gülen, thirteen years his senior. Erdoğan leads the ruling Justice and Development Party (AKP), and works in the political hurly-burly of Ankara, the country’s capital. Gülen is Turkey’s best-known preacher and moral didact. He lives in seclusion in Pennsylvania, reportedly in poor health (he has heart trouble). Gülen presides loosely but unmistakably over an empire of schools, businesses, and networks of sympathizers.

It is this empire that Erdoğan now depicts as a “parallel state” to the one he was elected to run, and he has undertaken to eliminate it. The feud began in earnest last December and has had a remarkably destructive effect. Many of Gülen’s followers work within the government and have had much power. Now large parts of the civil service have been eviscerated, much of the media has been reduced to unthinking carriers of politically motivated revelation and innuendo, and the economy has slowed down after a decade of strong growth. The Turkish miracle is over.

Erdoğan’s AKP government and the Gülen movement share a modernizing Islamist ideology, and although relations between them have been deteriorating for some time, before the current crisis it was possible to be affiliated with both. Coexistence ended abruptly on December 17, when more than fifty pro-AKP figures, including the head of Halkbank, a state-owned bank, a construction magnate, and the sons of three cabinet ministers, were taken in for questioning by prosecutors who are regarded as Gülen’s men.

The raids were allegedly carried out by Gülenist policemen and they were given much attention by newspapers and TV stations with a similar pro-Gülen bent. Allegations that the well-connected detainees were guilty of bribery, smuggling, and other crooked activities were tweeted and retweeted in a frenzy of condemnation; the Gülenist assault from within the government as well as outside it had been well planned. Incriminating evidence…