Today, of course, while the right still dabbles eagerly in the anti-fluoride, anti-vaccination, and other anti-science pathologies, the left may be the even greater culprit. Certainly the anti-fluoride coalition in Portland depended more on self-identified liberal voters than on conservatives. But there are key differences in how liberals and conservatives come by their fears. On the right, these mental illnesses stem from fear of government. On the left, their origins are a bit harder to pin down, but as I see it, they stem from an old mix of righteousness and the fear of contamination—from what we might recognize as Puritanism.

Let me give another example of left-wing Puritanism in action, one less glaring than the Portland referendum but which will be recognizable to many of you. Last month, at a birthday party for a three-year-old, I was hit with the realization that most of the parents around me were in the grip of moral panic, the kind of fear of contamination dramatized so well in The Crucible. One mother was trying to keep her daughter from eating a cupcake, because of all the sugar in cupcakes. Another was trying to limit her son to one juice box, because of all the sugar in juice. A father was panicking because there was no place, in this outdoor barn-like space at some nature center or farm or wildlife preserve, where his daughter could wash her hands before eating. And while I did not hear any parent fretting about the organic status of the veggie dip, I became certain there were such whispers all around me.