The “very stable genius” in the Oval Office is, in fact, extremely unstable, in word and deed. That’s not a psychological diagnosis, although you can make that case too. It’s just a straightforward description of his behavior. And his instability is starting to have serious economic consequences.

To see what I mean about Trump’s behavior, just consider his moves on China trade over the past month, which have been so erratic that even those of us who follow this stuff professionally have been having a hard time keeping track.

First, Trump unexpectedly announced plans to greatly expand the range of Chinese goods subject to tariffs. Then he had his officials declare China a currency manipulator — which happens to be one of the few economic sins of which the Chinese are innocent. Then, perhaps fearing the political fallout from the higher prices of many consumer goods from China during the holiday season, which would result from the tariff hikes, he postponed — but didn’t cancel — them .

Wait, there’s more. China, predictably, responded to the new United States tariffs with new tariffs on U.S. imports. Trump, apparently enraged, declared that he would raise his tariffs even higher, and declared that he was ordering U.S. companies to wind down their business in China (which is not something he has the legal authority to do). But at the Group of 7 summit in Biarritz he suggested that he was having “second thoughts,” only to have the White House declare that he actually wished he had raised tariffs even more.