Is academic freedom under threat on American campuses?

Concerns are rising over the state of academic freedom at American colleges and universities.

Charles Kesler, Professor of Government at Claremont McKenna; Geoffrey R. Stone, Professor of Law at the University of Chicago; David Brooks at The New York Times; and Peggy Noonan at the Wall Street Journal have all written recently about policies and actions in American higher education that seem to undermine free speech and academic freedom (click on their names to read the articles). 

What exactly is the nature of academic freedom? What is the purpose of a university? Robert P. George, a professor at Princeton, weighed in on this issue at First Things, commending Princeton for adopting a set of principles also endorsed by the University of Chicago. What are those principles? See here.