The change within the campus left occurred in part because some new departments (such as women’s studies) were founded by political activists. But that’s not the whole story. For a more complete explanation we must turn to Mill again. With respect to the two major strains of political thought, Mill said, “it is in a great measure the opposition of the other that keeps each within the limits of reason and sanity.” This remark gives us the meaning of the rise of radicalism within the campus left: where there are no right-of-center voices to keep the left intellectually on its toes, the once thoughtful analysis of the campus liberal left will degenerate into the incoherence of the radical left. The academic’s focus on careful analysis of and abstraction from all relevant evidence gradually gives way to the zealot’s selective use of partial evidence to bolster trains of thought fathered by political wishes and even fantasies, not by fact. Here Mill puts his finger on the mechanism that is at work as the one-party climate degrades the intellectual quality of the academy until, in his words, it breaches the limits of reason and sanity. This is where all of those campus horror stories come from; they are not atypical and isolated—they are the symptoms of a sickness that is systemic. Thus nonsensical conspiracy theories about 9/11 as the work of the U.S. government itself are what we must expect when the campus descends into a political monoculture.

(John M. Ellis, “How Serious Is the Damage?” Academic Questions 20 [winter 2006-07]: 14-21, at 16)