I spent five years on a PhD programme at an elite institute in one of the top four research universities in the UK. Some of the graduate students there were genuinely brilliant. But some couldn't think their way out of a wet paper bag. They still got PhDs, though, because they did everything their supervisor told them to.

Since leaving academia for industry, i have met a few more genuinely brilliant people. But they don't have PhDs, because that's not what you do in industry.

You can't make inferences about people's intelligence from their possession of PhDs. All it tells you is that they are capable of sustained hard work in trying conditions and on low pay, given a sufficient supply of coffee.

You miss my point... how do you "over produce" education?

It is not a 'product' it is a pursuit. It's like saying "Over producing exercise, or happiness".

Actually, it is a pursuit for the individual but a product for society. Ultimately, there exist two productive paths for a newly minted PhD - either join academia or enter the workforce. Both paths are governed by the laws of supply and demand. Ergo, it is possible to over-produce education, from the point of view of society.

Why does one have to be productive ?

You are mostly talking about American society as far as I can tell.

Why does one have to be productive ?

For sustained survival. It is reasonable to assume that anyone who decides to do a Phd is motivated to explore the depths of a topic and push the boundaries of human knowledge. However, that knowledge has value only in the scope of the world we live in. This value is governed by society, by us, and manifests itself as research grants, job opportunities etc. So one needs to consider this IF one wants to be productive (by doing a PhD). And of course, the whole point is void if one does not want to be productive, ergo, is not interested in his sustained survival.

This is a general observation. I don't see why it should be mostly about American society.