Millions of 18-year-olds are excited about heading to college this month — leaving home, making friends and taking courses that meet only a few hours a week. On the first day of classes, however, they may be startled to find that the professor who enters Calculus I or Intro to Philosophy is more than a half-century older than they are.

The phenomenon of the teacher who sticks around well past age 70 has been widely noted, yet colleges have had little success in mitigating its impact. A survey commissioned by Fidelity Investments and reported at Inside Higher Ed in June found that “some 74 percent of professors aged 49-67 plan to delay retirement past age 65 or never retire at all.”

Never retire at all? Another study cited in the article, this one using National Science Foundation data, calculated that since the 1970s only 28 percent of higher education faculty had retired by age 65.

Think of this from an employer’s point of view. In today’s economy, is there any worse policy than guaranteeing an employee the same job for 40-plus years, even if he or she meets few of the organization’s needs and costs a lot in the bargain?

That’s what tenure ensures. An assistant professor comes up for promotion at about age 35, and if the candidate qualifies, the school maintains him or her until the professor (or death) decides otherwise. Granting tenure in 2010 commits the school to that employee until 2050 or beyond.

No Flexibility

If a major was popular in the 1980s, and a school hired and tenured professors in response, the school keeps them regardless of how many majors the field has in 2010. The college not only has no flexibility to shift the workforce when demand goes down — a professor of sociology can’t shift to chemistry — but also has to pay a higher cost for the employee every year (because of ordinary salary adjustments, pension contributions and medical coverage).

Take the case of French professors. According to the Modern Language Association, the discipline recorded 248,000 course enrollments in 1980 in accredited, not-for-profit institutions (including two-year schools). In 1990, the number rose to 272,000, and in those heady years a certain number of faculty members hired to teach those courses won tenure. Since then, enrollments have dipped more than 20 percent, averaging about 207,000 for the last 10 years. For German, the drop is worse: 133,000 in 1990 to 95,000 today.

Obviously, some of these professors aren’t needed now. But ever since 1994, when mandatory retirement rules were ended, administrators can’t make them leave. As Columbia professor Mark Taylor put it in 2010, “Tenure decisions render illiquid a significant percentage of endowments at the precise moment when more flexibility is required.”

The only way to force a tenured professor out is to close an entire department, a step a few schools have taken. But no ambitious dean likes to face the fracas that ensues. When the State University of New York at Albany, for example, cut five low-enrollment humanities programs, an NPR story on it highlighted the “outcry” that followed which “resonated with the public and the press.”

Most professors in slipping fields don’t notice the effects much. Tenure frees them from worrying about student interest. They love having smaller classes and fewer papers to grade.

The standard course universities have taken is to offer buyout packages to accelerate retirements. But that old tactic may no longer work. It’s not just the bad job market.

In the Fidelity survey, professors ranked personal reasons more often than financial concerns for continuing to work. Only 55 percent declared that uncertainty over having enough money to retire comfortably was their main reason for staying, while 89 percent said they “want to stay busy and productive” and 64 percent said they “love the work too much to give it up.”

Hiring Changes

What’s a manager to do when an expensive and not-so-productive 73-year-old worker can’t be released or reassigned? The obvious answer is to stop the process before it starts, and use more nontenured instructors.

In 1969, tenured and tenure-track faculty amounted to 78 percent of the higher education workforce. By 2009, that rate had slipped to 33 percent, even as the number of professors over 65 doubled from 2000 to 2011, the Bureau of Labor Statistics reports. Faculty leaders complain about the trend, citing the bad wages and benefits in nontenured employment. But the Fidelity survey explains why administrators have no choice.

Tenure started 100 years ago as a way to preserve academic freedom, not to keep employees in place 10 years past customary retirement age. The continued resistance to reform shows arrogant disregard for rising college costs for students, for meritocratic decision-making and for academic innovation.

The current method of converting tenured slots to nontenured ones is too slow. We need another incentive, and there is none more powerful among selective institutions than the U.S. News rankings, which scare administrators every year. What if the rankings included another variable, “Percentage of professors over age 65”? No university wants to top that list, and we can be sure that once it appears, a whole new set of creative solutions to the never-retiring professor will be found.

Mark Bauerlein

Mark Bauerlein is a professor of English at Emory University and an occasional contributor to Bloomberg View.