Time was, presidential years featured solemn sermonettes about the citizen’s duty to vote, and the virtue of prodding the apathetic to plod, even if sullenly, to the polls. There has, however, always been a twofold difficulty with such civic piety: Even in normal times — remember those? — there was no such duty. And hectoring the uninterested and indifferent to express their opinions with ballots must lower the caliber of election results.