Trudy Rubin: Turkey must show clear evidence that cleric in U.S. was involved in coup attempt

Could an old man in Pennsylvania really be responsible for an attempted coup that nearly unseated a NATO ally and threatens America’s fight against ISIS? That’s the claim of Turkish president Recep Tayyip Erdogan, who is demanding that the United States extradite Fethullah Gulen, a 77-year-old Turkish cleric living on a 26-acre retreat, whom he blames…