Whether Jewish or gentile, liberal or conservative, we supporters of Israel must admit we haven't always framed our defense of the Jewish state in the most fair-minded of ways. Our opponents in this arena—Israel-bashers in politics and the culture, across parliaments and campuses—too often play with one hand tied behind their backs. Call it the test of antisemitic motives: whether openly or surreptitiously, anyone opposing a particular policy or constitutional feature of Israel is immediately suspected, as many have complained, of harboring antisemitism or connivance with Palestinian terror. This is done, both deliberately and accidentally, by conflating two different stances....