The veil of secrecy shrouding the detention of Osman Kavala, a tireless and generous supporter of civil society in Turkey, has yet to be lifted since his detention at Istanbul’s Ataturk airport on Oct. 18. But the slander campaign against the prominent businessman and philanthropist is continuing full blast. Aydin Unal, a columnist for the pro-government Yeni Safak, likened Kavala to Fethullah Gulen, the Pennsylvania-based imam who is accused of seeking to violently overthrow Turkish President Recep Tayyip Erdogan. “It is quite clear that Kavala, just like Fethullah Gulen, is one of the baby-faced, masked as peace-loving, humanitarian-seeming tools collected...