One stream of our political discourse right now pits self-aggrandizing progressives who are not themselves scientists but wish to associate themselves with the prestige of science (“We believe in science!” etc.) against right-leaning populists who abominate what they call “elitism” and who wish to lower the status of certain elites and elite institutions (Silicon Valley, Wall Street, the Ivy League, etc.), a face-off that produces very little more than a mutual and self-reinforcing sneer. Our friends on the Left can turn anti-expertise just as quickly — see Alexandria Ocasio-Cortez on why it is more important to be “morally right” than “factually correct.”

I remember a few years ago a headline in the New York Times that reading something like: Why are the jails so full when crime rates are going down? The answer from those who advocate more aggressive sentencing and law enforcement was: Crime rates are going down because the jails are so full. Criminal justice measures at the time were relatively aggressive, and crime rates were going down — everybody agreed on the facts, but there was no broader agreement. Many people believe very deeply that New York City’s crime rates went down dramatically at the turn of the century because of the policies of Rudy Giuliani, who used to be a mayor before he became whatever it is he is today. But crime also went down in similar cities around the country and around the world, including in places where no similar policies had been pursued. We have a great deal of information about that era and some plausible stories about why that wondrous change happened in New York City. But the fact is that nobody really knows, and what people “know” is mostly determined by cultural and political affiliations, not by knowledge.