In August, a day after Kamala Harris accepted the Democratic nomination for president, a conservative-against-conservative argument erupted on social media. Steve Hayes, the editor and CEO of The Dispatch, called out his fellow conservatives for “fluffing” the progressive Harris and “embracing” the “nutty” Robert F. Kennedy Jr. “What a mess the modern conservative movement is,” he sighed. The pile-on was swift. Sarah Longwell, publisher of The Bulwark, was first. “Honestly, what are you talking about Steve?” she wrote. The problem with the conservative movement, she said, was the capitulation to Donald Trump, not the opposition against him. Hayes shot back:...