You know our political discourse has lost its moorings when it’s the Republicans who play that famous race card in defending one of their own. The person in need of defense is Dr. Ben Carson, a renowned Johns Hopkins surgeon. Carson happens to be black, Yale-educated — and conservative. After his impassioned criticism of President Obama at the National Prayer Breakfast, many in the GOP thought they’d found their 2016 standard-bearer. But however brilliant, Carson has raised eyebrows since coming into the spotlight. Last week, he told Sean Hannity, “Marriage is between a man and a woman. No group, be...