(CNN)Rupert Murdoch threw a grenade. J.K. Rowling caught it in midair and lobbed it back. The explosion -- in the battlefield of social media -- injured the truth. Murdoch, the conservative media magnate, never afraid to ruffle liberal feathers, tweeted that Muslims "must be held responsible" for "their growing jihadist cancer." Rowling, the creator of Harry Potter, deployed her rhetorical mastery. "I was born Christian," she tweeted back. "If that makes Rupert Murdoch my responsibility, I'll auto-excommunicate." At last count, more than 20,000 people had re-tweeted her. The comedian Aziz Ansari shot back, "Rups can we get a step by step guide? How can my 60 year old parents in NC help destroy terrorist groups? Plz advise."
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Frida Ghitis: Rupert Murdoch tweet: Muslims must be accountable for jihadist 'cancer'
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J.K. Rowling, Aziz Ansari tweet: Are all Christians accountable for evil done by some?
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Ghitis: Both extremes wrong. All Muslims not guilty, but must play role in fighting jihadists
@placeholder, for one, with a large following and gift for communicating his views, has the ability to advance the conversation away from both extremes.