Amid a national debate on whether colleges are open to all viewspoints, Brown University's president gave a surprising talk to students Tuesday to welcome them back for the spring semester.

Ruth Simmons, the president, told them she was concerned about reports she hears from students, parents and alumni about "the lack of diversity of opinion on campus." Students have told her of a "chilling effect caused by the dominance of certain voices on the spectrum of moral and political thought," according to an account of the speech in The Brown Daily Herald.

Simmons was not available to comment Wednesday and did not release a copy of her remarks. But a Brown spokesman said that the student newspaper's account did reflect her views.

Several prominent critics of higher education in general, and of Brown in particular, called the talk significant and praised Simmons. In conservative circles, Brown has long been bashed for being politically correct and squelching non-liberal ideas, so the idea that the university's president would speak out as Simmons did was viewed as a big deal.

According to The Brown Daily Herald, Simmons urged students to avoid just talking to and taking courses from people with whom they agree. "Familiar and appetizing offerings can certainly be a pleasing dimension of learning, but too much repetition of what we desire to hear can become intellectually debilitating," she said.

Simmons also told students to engage in civil, open debate on every issue possible, and said people at Brown need to ask why the university has a reputation for "limiting debate" and "fostering hostility to particular ideas and different perspectives."

To help bring diverse views to the campus, Simmons said she was creating a new fund to bring a wider variety of speakers to the university.

Stephen H. Balch, president of the National Association of Scholars, said he was "delighted" by the speech. He said he hoped this would become a "leadership event" that would be recognized as significant by other college presidents.

Balch, who called himself a frequent critic of Brown, said he thought it was particularly fitting that a call for ideological diversity would come from that university. Brown earned the enmity of many conservatives by adopting a curriculum without much in the way of requirements.

As Balch put it, "the university lets students wander through the groves of academe, but if each and every tree that the students see is the same," then what is the purpose of the freedom given to students?

Also praising Simmons was David Horowitz, who has had fierce battles with Brown in the past.

In 2001, Horowitz, who was once a campus radical but has moved rightward ever since, took out an ad in The Daily Herald denouncing the idea of the United States paying reparations for slavery. Students who were angered by the ad threw out most of the copies of that day's newspaper, setting off a major national debate over free speech and political correctness.

Horowitz is still not ready to say that he is happy with Brown. He cites the "near monopoly" of campus speakers from the left and the "one-sided nature of Brown's faculty." But he praised Simmons. "I agree and support the general tenor of Dr. Simmons's remarks. Intellectual diversity is an endangered value on American campuses generally and at Brown in particular." He noted that the last time he spoke at Brown, Simmons came to the talk -- something presidents at campuses he visits never do.

In his national campaign on that issue, Horowitz is pushing an "Academic Bill of Rights" -- in Congress and in state legislatures -- that he says would bring ideological diversity to campuses, but that critics say is an attempt to squelch liberal thinkers.

Asked if he would drop his campaign if the ideas Simmons talked about took hold, Horowitz said that if such ideas were not just talked about, but carried out nationally, he would "joyously retire."