Ben Carson’s presidential campaign is surging on a wave of support from socially conservative voters inspired by his passionate talk about faith and his attacks on Planned Parenthood. But while Carson insists he’s a fierce opponent of abortion, he also defends a long series of actions on the issue that are sharply at odds with the beliefs of the very voters fueling his rise. Carson, a retired pediatric neurosurgeon, has referred women to doctors who perform abortions, was a trustee of a foundation that gave hundreds of thousands of dollars to Planned Parenthood, and his campaign struggles to articulate which...