The short answer
Mostly that a person can turn up, focus and finish something long. That's worth knowing, but it can be shown directly in about a month, and the degree says much less about what a person can do.
Economists have a name for what a degree does. It's a signal. Michael Spence described it in 1973: when an employer can't see skill, they look for something they can see. Bryan Caplan has argued that part of what the signal shows is persistence. Can this person stay with four years of it?
That's a real thing to know. But ask what else the paper tells you. The most common grade in American colleges is now an A, about four in ten. In a 2014 survey, 96 percent of college provosts said they were preparing students well for work, and about 11 percent of business leaders agreed. So the paper has gotten softer, and the people reading it have noticed.
Why? Look at what's asked. Full-time students studied about 24 hours a week in 1961 and about 14 in 2003. Richard Arum and Josipa Roksa found that close to half of students showed little improvement in reasoning and writing in their first two years. That points at what the system asks of students, not at the students. A demanding course is expensive to run. An easy one costs less. Nobody has to want that for it to happen.
If the degree mostly shows you can learn, focus and be trained, you can show those directly. Tell a person ahead of time what they'll be tested on. Give them a few weeks. Then have them do it, for real, in front of someone who does the work. You don't need four years to find out whether someone can learn. You need to watch them learn something.
And the book's view is that this ability should be built long before college, in childhood.
If you're hiring, ask what the degree was standing in for in this role, then test that directly. If you're a student, collect proof of what you can do alongside the degree: finished work, written feedback, someone who does the job willing to vouch for it.
This is about the four-year bachelor's as a general ticket. Medical school, nursing programs, apprenticeships and engineering tracks give real training. And four weeks shows that a person can be trained. It doesn't make anyone a surgeon or an engineer.
The one useful thing a bachelor's degree certifies, that a person can learn, focus, and be trained, can be shown directly in about a month instead of four years.
A credential almost anyone can buy, and almost no one can fail, isn't proof of anything. It's a receipt.
The ability to focus, carry a project through, and teach yourself should be built by about age ten, not purchased at twenty-two.
A college that sells you a degree that doesn't get you hired often gains you as a customer for the next degree, and an easier course costs less to run.