The university is reviewing courses under new rules restricting teaching about race and gender. Administrators told a philosophy professor to cut some lessons on Plato to comply.

Martin Peterson, a philosophy professor at Texas A&M University, was thunderstruck when he was told on Tuesday that he needed to excise some teachings of Plato from his syllabus. It was one way, his department head wrote in an email, that Dr. Peterson’s philosophy class could comply with new policies limiting discussion of race and gender.

Days before the start of the spring semester, one of the nation’s largest public universities is racing to interpret and enforce the A&M system’s rules. Some professors are reconsidering syllabuses at the direction of administrators, or are unsure whether they will be able to lead certain classes. Course sections are being canceled or potentially reclassified, threatening students’ schedules.

And professors are worried that they are losing the academic freedom they prize.

“A philosophy professor who is not allowed to teach Plato?” Dr. Peterson said in an interview on Wednesday. “What kind of university is that? Is that really what they want?”

“How,” he added, “can we possibly teach philosophy without being allowed to discuss Plato, even if some of Plato’s ideas are a little bit controversial?”