I don’t know what’s changed in more recent years, perhaps the economy, but it doesn’t seem to be like that these days. Students often work part-time, they choose courses on the basis of job prospects and they limit the time they spend on campus. If I had my way, I would recommend the full university experience to everyone, but I’d be wrong. Financially, there’s an advantage, one I didn’t know much about at the time. Over their lifetimes university graduates earn 40 to 75 per cent more than workers who go to work straight from school. One estimate puts the lifetime earnings of male graduates at $2.3 million compared to $1.7 million for those who go straight to work. The earnings of female graduates are put at $1.8 million compared to $1.4 million. You might have noticed those figures say nothing about whether or not university education is the cause of those extra earnings. Those people might have done well anyway. It is my unfortunate duty to tell you most would not have. University education brings about extra earnings, rather than being merely associated with them. An ingenious Australian study of identical twins (“by definition, the same innate ability and family background”) found that it’s the twin that does the extra study that gets the extra earnings.

Research conducted by Dr Andrew Leigh, now a member of parliament, found that each extra year of education beyond Year 10 added an extra 10 per cent to lifetime earnings. But it didn’t answer the more important question: what is it about those extra years that makes the students so much more valuable? If you think the answer is "learning more stuff" you’ll have to answer to Bryan Caplan. A university professor himself, he has just published a book titled The Case Against Education. Its implications are enormous. He is in no doubt that graduates earn more, and that graduation is the reason. But he thinks it has little to do with what they learnt. Consider two students who had each learnt as much. One had a family tragedy and couldn’t sit the final exam, the other could. US statistics show that the one who got the final piece of paper earns roughly 10 per cent more than other people for each extra year of education, whereas the one who learnt the stuff but missed out on the certificate gets only 4.2 per cent more. Or ask someone whether they would have rather have learnt stuff without getting a degree or got a degree without learning stuff.

And what could they possibly have learnt at university that would be of use to an employer anyway? Calculus? Literature? Most jobs don’t even require algebra, and literature doesn’t help people write, which is what’s required in jobs. There are exceptions: economics might be one, engineering another. But most courses teach things that aren’t useful for employers. So why do employers pay so much for people who’ve done them, or at least have got the certificates to show they once did them? Caplan reckons it’s profiling, a bit like racial profiling, where police use the way someone looks as a rule of thumb to work out whether they are likely to commit a crime, or the profiling by insurance companies who use postcodes to tell them what to charge. It mightn’t be fair, but it's quick. Seen that way, university is a sorting tool for employers, one they don’t pay for. It helps them identify characteristics that will be needed on the job but have nothing to do with what was learnt. One is intelligence. You need a certain amount to get enough marks to pass, whatever the subject. Another is consciousness. You need to apply yourself. And the third is conformity. Sane free-thinkers realise quickly there’s not a lot of point to what they are learning and drop out. Degrees certify IQ, the ability to knuckle down and a worker who won’t make trouble. So they are great for employers and great for graduates, albeit at the cost of enormous wasted resources. Employers could get the same outcomes if the courses lasted for two years instead of four, or even one. Or if they administered tests themselves.

If Caplan’s right, we should be pushing politicians for less education rather than more, especially as the ageing of the population makes workers more scarce. My own company, Fairfax, is doing just that. It has taken on several truly excellent journalists precisely for the reason that they left university rather than see it through. They wanted to do the job rather than study it. University isn’t for everyone, but life is. And it’s even better than university. Peter Martin is economics editor of The Age. Follow Peter Martin on Twitter and Facebook