The debate over the future of the Democratic Party’s foreign policy has become intensely personal. In May, Senator Brian Schatz of Hawaii posted on social media that although he did not favor “black listing,” he thought it nevertheless “fair to want a whole new crop of foreign policy staffers in the next democratic administration.” After all, he added, “it’s not like the same 120 people are the only people who know anything.” His post followed a stream of stories and social-media commentary call