In January, Canadian Prime Minister Mark Carney warned leaders gathered at the World Economic Forum in Davos that states caught between Washington and Beijing needed to stop negotiating alone. “If we’re not at the table,” he said, “we’re on the menu.” The line captured the mood of the moment. Across capitals and conferences, middle powers are suddenly back in fashion. Think tank reports and newspaper columns describe India as a pivotal swing state; hold up Brazil, Indonesia, Saudi Arabia, and Turkey as models of successful hedging; and urge Australia, Canada, Europe, Japan, and South Korea to coordinate more and rely less on the United States. A new vocabulary has followed: strategic autonomy, multialignment, minilateralism, variable geometry. The usual interpretation is that all this activity marks the arrival of a multipolar world. The United States is losing its grip. The rise of the rest has created alternatives to the Western-dominated order.…