Even before President Trump’s election, hatred had begun to emerge on the American left—counterintuitively, as an assertion of guilelessness and moral superiority. At the Women’s March in Washington the weekend after Mr. Trump’s inauguration, the pop star Madonna said, “I have thought an awful lot of blowing up the White House.” Here hatred was a vanity, a braggadocio meant to signal her innocence of the sort of evil that, in her mind, the White House represented. (She later said the comment was “taken wildly out of context.”)

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