In a lawsuit filed this month against Northwestern University in Illinois, pro-Palestinian activists sought to halt the school’s required antisemitism training. The training requires students to watch a video that outlines historical Jewish connections to Israel, says that most forms of anti-Zionism are antisemitic, and states that those views are “representative of the majority of Jewish people.” The pro-Palestinian activists allege the video is discriminatory, including against anti-Zionist Jews, who, the lawsuit states, “are also a cognizable ethnic group” covered by federal civil rights protections. But are anti-Zionist Jews a significant bloc of the American Jewish community, or insignificant outliers?...