When the University of California Regents rescinded former Harvard president Lawrence Summers's invitation to speak at a Board dinner this month, it was too easy to link Summers with Erwin Chemerinsky: Just days before, the University of California at Irvine had rescinded Chemerinsky's invitation to serve as dean of their new law school. While the two cases share some common elements--in both, the officials reneged under pressure on commitments presumably made in good faith and for good reasons--the superficial similarities conceal deep differences. In the Chemerinsky case, UC threatened Chemerinsky's academic freedom; in the Summers case, UC threatened mine--and that of everyone else who teaches here.

UCI unhired Erwin Chemerinsky because, he said, they were worried about "conservatives out to get me," and they knew some of the UC Regents would vigorously oppose him. This threat almost certainly came from someone outside UCI: maybe the politician who said appointing Chemerinsky dean would be "like appointing Al Qaeda in charge of homeland security," maybe a discontented donor, maybe both.

Universities' vulnerability to outside pressure is what brought us academic freedom in the first place. In 1900, the Stanford economist-turned-sociologist Edward Ross said he opposed immigration because it threatened Anglo-Saxon racial purity. Jane Stanford, widow of railroad tycoon Leland Stanford and benefactor of the university (as well as beneficiary of immigrant labor) insisted Ross be fired. Ross countered, "It is my duty as an economist to impart ... in a scientific spirit, my conclusions on subjects with which I am expert." Mrs. Stanford won.

The Ross case inspired what became the American Association of University Professors' 1915 "General Declaration of Principles." In it, the AAUP explained universities must act so it is clear that "what purport to be the conclusions of men [sic] trained for, and dedicated to, the quest for truth, shall in fact be the conclusions of such men, and not echoes of the opinion of the lay public, or the individuals who manage or endow universities." Otherwise the truth is imperiled.

As the AAUP's 1915 statement indicates, academic freedom differs from freedom of speech. Scholars enjoy it not because they have First Amendment rights (indeed, as the historian Thomas Haskell points out, in 1915, nobody had the First Amendment rights Americans enjoy today) but because of their training and participation in a specialized community of inquiry. What Ross said, though unpleasing to us and indeed to many decent people in 1900, was at the time within the realm of legitimate sociology. His ideas demanded investigation and critique--not firing.

Insofar as UCI succumbed to "the opinion of the lay public, or the individuals who manage or endow universities" when it unhired Erwin Chemerinsky for expressing opinions within his expert competence (including especially his comments on now-resigned Attorney General Alberto Gonzales), they obviously violated a core canon of academic freedom. Perhaps because the case was so blindingly clear, UCI un-unhired Chemerinsky.

Summers's case differs. Here, the objection came from within the community of scholarly inquirers at UC Davis who organized a petition signed by UC professors who believe it "inappropriate at a time when the University is searching for a new president" to invite Summers, who "has come to symbolize gender and racial prejudice in academia" since his clash with African American Studies professor Cornel West and his 2005 comments on genetic differences in scientific aptitude between men and women.

You might think this looks a lot like the case of Edward Ross--in both, a northern California university doesn't want to hear from an economist talking the sociology of innate differences. But there are key distinctions. Summers doesn't work here and, as one of his Harvard colleagues points out, he doesn't have the right to "speak anywhere and everywhere" or indeed on everything.

What's more, academic freedom depends on reactions like the response to Summers's 2005 comments. Knowledgeable scholars including the sociologist (and my colleague) Kim Shauman explained that there was actually a great deal more research into, and knowledge of, the ways women founder in scientific careers than Summers had originally suggested. Summers, Shauman said, was "uninformed." As the economist Brad DeLong noted, "Summers's views on gender, genetics, and math achievement are almost certainly wrong, are unsupported, and should not be pushed forward by somebody who is twenty years beyond the stage of his career where you throw out lots of unfiltered ideas in the belief that what matters is the quality of your best one." For the scholarly community to retain its rights, it must present evidence and argument to define what is and isn't good scholarship--that's how the ideas of, say, an Edward Ross become known as bad sociology.

Chemerinsky lost a deanship for expressing expert opinions that rubbed someone the wrong way. His case tells UC professors we should watch what we say in the newspapers, which is bad enough. Yet the proscription of Summers represents, in principle, a more serious limit to academic freedom on UC campuses: Lawrence Summers and his ideas are apparently unhearable here.

Last week the AAUP reaffirmed and elaborated its long-standing commitment to academic freedom by discussing what kinds of material professors can present. Some political campaigns have demanded that professors exhibit more "balance" and keep controversial opinions out of their teaching, seizing on a 1940 AAUP statement that professors "should be careful not to introduce into their teaching controversial matter which has no relation to their subject." AAUP responded by saying academics were obliged to do no such thing. "Controversy is at the heart of the free academic inquiry," AAUP holds. As Michael Bérubé points out, "'controversial' matter, in and of itself, is not a problem; rather, irrelevant material is the problem."

By succumbing to a demand that they reject a controversial, though--as a former treasury secretary, university administrator, and respected economist--obviously relevant speaker, the Regents have suddenly made life much more difficult for those of us in the business of presenting controversial, if relevant, ideas and guest speakers on UC campuses. Casting someone as utterly outside the university's conversation is the severest penalty we as scholars can impose--appropriate perhaps to Holocaust deniers and such ilk as exhibit a chronic impenetrability to reason. Lawrence Summers, though he said some things well worth objecting to, falls well short of that standard. By applying this ban to him, the Regents suggest an impossibly low tolerance for controversy at the University of California.

By Eric Rauchway