I’m in Europe for a few weeks, giving myself some physical (if not mental) distance from Trumpland. So I decided to take a short break from my healthcare series to write about the European economy — specifically the perception that Europe is in economic decline. According to conventional wisdom, Europe is falling far behind the United States. It has lost any dynamism it once had and is quickly becoming a museum of its former glories. This perception is widespread: at Davos in January Howard Lutnik, Trump’s Commerce secretary, gave a speech that was so insulting toward Europe that Christine Lagarde,...