I know more about climate change than Tony Blair; if I had a dog and had taken it on my last trip to see Jim Lovelock it would know more about climate change than Tony Blair.
He's right, but misses the point. What Blair's selling is not expertise but contacts - not human capital but network capital.
And there's tons of evidence that network capital matters. Knowing other researchers allows scientists to collaborate on generating ideas. Social capital is often crucial in helping scientists turn inventions into companies. Non-executive directors are often useful not so much for their expertise as their contacts with suppliers or customers. And it's a knowledge of other people that helps entrepreneurs make money; any good salesman will tell you that it's at least as important to know your customer as your product.
It's for reasons like this that the internet and mobile phones can boost economic growth, particularly in Africa, and this may be why the privately educated earn more than the state educated, even controlling for qualifications.
Indeed, it could be that network capital is actually more important in raising incomes than human capital. I mean four things:
1. What looks like a return to experience is in fact a return to knowing more people. If you've done a job for a few years, you'll have met likely employers and your reputation will have grown. Beyond a certain point, it may be these that raise your earnings more than the technical skills you've acquired from an extra year of work. This, surely, accounts for Blair's high earnings now.
2. Returns to human capital might be over-estimated, if a university education serves to signal ability rather than merely develop it.
3. This lovely paper (pdf) by Marcel Fafchamps estimates that, among agricultural traders, network capital gives a higher return than human capital.
4. Macroeconomic evidence for a strong link between human capital and subsequent growth is surprisingly weak; see, for example, the critiques here (pdf) here (pdf) and here (pdf).
Which brings us to a nice irony. Blair famously said the key to economic success, for individuals and economies, was "education, education, education." But his subsequent career demonstrates that what might be more important are "contacts, contacts, contacts."