THREE DECADES ago, a German history professor listed 210 proposed explanations for the fall of the Roman Empire. The remarkable array included such fanciful causes as Bolshevism, public baths, hedonism, the pressure of terrorism and, most famously, lead poisoning. The last explanation has been discredited. It is highly unlikely that lead water pipes caused the ...

After the election, many people blamed Facebook for spreading partisan — and largely pro-Trump — “fake news,” like Pope Francis’s endorsement of Trump, or Hillary Clinton’s secret life-threatening illness. The company was assailed for prioritizing user “engagement,” meaning that its algorithms probably favored juicy fake news over other kinds of stories. Those algorithms had taken ...