Not all wars are examples of diplomacy failing. The economic war that Trump has set up is a personal affair, that he didn’t negotiated with anyone; although at Davos he commented that a weak dollar would help U.S. trade. And it will; it will make U.S. goods less expensive than similar goods from other countries. That should help U.S. manufacturers to some degree. But a weak dollar will make the U.S. less desirable as a place to invest, because it will lower the values of capital assets, especially ...