Academia is once again in the news. Donald Trump’s recent commencement address at the University of Alabama, where he said that America’s “next chapter will not be written by The Harvard Crimson, it will be written by you—the Crimson Tide,” sounded one leitmotif of the new, Trump-inspired populism that is washing over the academic establishment. Trump’s announcement that he was seeking to remove Harvard’s tax-exempt status sounded another.

These days, whenever the public’s attention is roused by academia, the oculus of media scrutiny turns up references to my book Tenured Radicals, first published more than 30 years ago but subsequently expanded and updated several times.

Given the renewed interest in academic culture, I thought I would adapt a few thoughts from the introduction to the most recent edition of the book.

Academic life, like the rest of social life, unfolds within a frame of rules and permissions. At one end, there are things that one must (or must not) do; at the other end, there is the rule of whim. The middle range, in which behavior is neither explicitly governed by rules nor entirely free, is that realm governed by what the British jurist John Fletcher Moulton, writing in the early 1920s, called “Obedience to the Unenforceable.”