A lot of people are in a funk over President Trump’s decision to recognize Jerusalem as Israel’s capital. The liberal media, most former government officials who’ve dealt with the Israeli–Palestinian imbroglio, and just about everyone at the United Nations appear certain that the decision had a lot to do with Mr. Trump’s disruptive nature, the president’s son-in-law Jared Kushner, Evangelical Christians and pro-Israel Republican donors.

It’s possible that his decision was based instead on an old-fashioned understanding of...