I disagree with you. They may be a noisy measure, but they are not meaningless. If I have ten technical positions, and for each one I interview someone from MIT and someone with a two-year degree from community college, I'm pretty sure that at least 9 of those 10 positions are better filled by a MIT grad.

OK, but the fact that you said, "at least 9 of those 10" instead of "10 out of 10" suggests that we're not really disagreeing. I'm not saying they're completely meaningless, but they are extremely noisy, to use your term, and very expensive to obtain, in terms of time and money.

90% signal is far from "extremely" noisy.

Don't focus too much on the S/N analogy. Remember, a legal barrier is equivalent to a claim of 100% accuracy, so even 90% (which wasn't my number, anyway) is terrible. What he and I apparently agree on is that the accuracy is less than 100%.

How is it a legal barrier? He's free to hire someone with the CC degree, or no degree at all. Degrees serve as an indication of knowledge (not to mention commitment), just like experience, test scores, or any other means of evaluating someone's merit. And I don't know anyone who thinks that a degree from any school is 100% proof of anything. It's just an indicator.

I think it's ridiculous to think that utopia is a world in which credentials are ignored. And they're only part of what helps people get jobs...this argument is like saying that we shouldn't use interviews for jobs because some people aren't very friendly and are therefore at a disadvantage.

The actual problem is not credentialism per se, but legal credentialing requirements that are pushed by the professional lobbies for the purpose of creating artificial barriers to entry.

For instance, lawyers used to be able to pass the bar and become a lawyer by simply self-studying and passing the tests. The bar associations wanted to raise the barriers to entry to the profession, so they passed laws requiring a Law school degree. Students then started taking correspondence courses. The bar associations then changed the accreditation rules to mandate a minimum amount of classroom face time. These artificial credentialing laws ended up hurting the poor. Because before a student could study with books from a library card and become a lawyer. Now he must pay a very expensive tuition bill. Also, the artificial barriers to entry drive up wages for the credentialed professions, which means everyone has to pay more for doctors, legal help, etc.

Something like 30% of all jobs in the United States now have a legal credentialing requirement. Other companies are forced to use college attendance as a proxy for IQ tests, simply because the Supreme Court made it illegal to use IQ tests in hiring.

Again, I'm saying that actual ability is more important than credentials, not that credentials will be completely ignored. As for legal barriers, it looks like bokonist has already addressed that here.