Most colleges and universities encourage students to express their views about social and political issues, but the marketplace of ideas often ends inside the locker room. That’s what Josh Rosen, UCLA’s standout quarterback, may be learning from his coach, Jim Mora.

In mid-July, at the Pac-12 Media Day, Mora admonished Rosen to be “socially responsible.” Mora had already cautioned Rosen earlier in the year for criticizing Donald Trump and for challenging the university’s licensing deal with a sporting goods company.

In April, Rosen posted an Instagram photo of himself playing golf at one of Trump’s courses while wearing a hat that profanely disparaged the Republican presidential candidate. (A later Instagram revealed that he also had a poster in his dorm room with the same anti-Trump message.) The next month, after UCLA announced a 15-year, $280-million apparel deal with Under Armour, Rosen posted a sarcastic message: “We’re still amateurs though … Gotta love non-profits #NCAA.” And before that, he had posted a picture of himself and a female student sitting in an inflatable hot tub in his dorm room.

Mora, in an L.A. radio interview in May, warned Rosen against following the bad example of Johnny Manziel, the former Cleveland Browns quarterback caught up in scandals relating to abuse of women, drugs and alcohol. Then Mora suggested that Rosen should emulate pro quarterbacks Tom Brady, Peyton Manning and UCLA alumnus Troy Aikman. All three have had successful NFL careers, and all three are politically conservative. Brady is a friend of Republican presidential candidate Donald Trump, and Manning and Aikman have donated thousands to GOP Senate and presidential campaigns. 

Maybe Mora was merely trying to give Rosen some friendly career advice: Don’t alienate fans or jeopardize potentially lucrative commercial endorsements. But Mora’s picks for positive role models fit into a disturbing pattern in college sports: Outspoken conservatives are admired and forthright liberals, not so much.

For example, since 1964, the American Football Coaches Assn. has bestowed an annual award to “service to others.” Almost all the winners have been politically conservative types, including FBI director J. Edgar Hoover; evangelist Billy Graham; Presidents Richard Nixon, Gerald Ford, Ronald Reagan and George H. W. Bush; actor John Wayne; General Electric Chief Executive Jeff Immelt; former University of Nebraska coach and Republican Rep. Tom Osborne; and former New York Mayor Rudy Giuliani.

Last year, when Northwestern University football players tried to form a union, the school’s head coach, Pat Fitzgerald, led the opposition. Fitzgerald characterized the unionization attempt as a personal betrayal. Former Northwestern quarterback Kain Colter pointed out that college student-athletes live under rules and regulations that resemble a “dictatorship.”

At the Pac-12 news conference, Mora gave lip service to Rosen’s right to express his opinions. Referring to former UCLA basketball stars Kareem Abdul‑Jabbar (then called Lew Alcindor, who graduated in 1969) and Bill Walton (class of 1974), Mora acknowledged that UCLA had “a long history” of “socially aware” students who were “not afraid to rattle the cage a little bit.” But, Mora added, it is now a “different world” where anything Rosen says will be “analyzed and sometimes overanalyzed,” so he should be “socially responsible.”

Of course, Walton and Abdul-Jabbar did more than “rattle cages” while at UCLA.

According to John Matthew Smith, who wrote a history of UCLA’s basketball program, Abdul-Jabbar was “born a child of the civil rights movement [but] grew into a man of the Black Power era.”

While at UCLA, Abdul-Jabbar publicly supported Muhammad Ali’s controversial refusal to enter the Army because of his anti-war beliefs, and he protested the shooting of African Americans by police. “We catch hell because we are black,” he told a 1967 youth conference in Los Angeles. His decision to forgo a spot on the 1968 Olympic team to volunteer with inner-city kids instead invited rabid and racist condemnation. 

Walton led campus protests against the Vietnam War and in 1972 was arrested during a demonstration. His conservative coach John Wooden chastised him and many newspaper commentators condemned his actions.

UCLA athletes’ activism often went beyond outspoken individuals. The 1970 championship basketball team signed a letter to President Nixon condemning his “expansion of the immoral, genocidal and imperialistic war the United States is now waging in Southeast Asia” — not everyone’s idea of socially responsible behavior.

College athletes are nascent public figures. It isn’t surprising that they are counseled to play it safe. Following Rosen’s controversial postings, UCLA senior tackle Conor McDermott made that clear when he told the Arizona Daily Star that his young teammate was “very smart and likes to talk about his opinions. But some things you have to keep to yourself.”

Rosen is a smart, and apparently irreverent young man with a liberal social conscience. He shouldn’t be intimidated. Still, he might want to get beyond brash mottoes and truncated tweets. Walton and Abdul-Jabbar were students of U.S. political and social history. They could back up their opinions with analysis and evidence. They were criticized for their views, but their outspokenness didn’t prevent them from pursuing lucrative careers in professional sports. 

Whether liberal or conservative, college athletes have a right to speak out. When they do, they are going to have to defend their ideas, face some backlash and lose some fans. Josh Rosen needs to sharpen his analysis, not shut his mouth. 

Peter Dreier is professor of politics at Occidental College and author of “The 100 Greatest Americans of the 20th Century: A Social Justice Hall of Fame.” Kelly Candaele produced the documentary “A League of Their Own” about his mother’s years in the All American Girls Professional Baseball League.

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