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Turkey’s political discussion changes quickly. Yesterday it was mostly Syria. Today it is making peace with Kurds. That has been a boon to prime minister Recep Tayyip Erdogan’s political standing—at least for the moment.

2012 marked the AKP’s ten-year anniversary as the ruling party, a rare feat in Turkish politics. The party has been one of the few constants in a new, more vital Turkey. But it was a difficult year for Erdogan because of Syria’s unending civil war. After a year of intense criticism over his handling of Syria, including from members of his own party, Erdogan’s political fortunes seemed to be suffering.

For the first time, the prime minister was losing public support, and his effort to constitutionally change Turkey’s...