He taught me Ph.d Micro I at Harvard, so it’s too bad he wants to wreck both Spain and Europe, and for so little in return. Didn’t one of his theorems suggest this was a bad idea? It’s not as if Catalonia is treated like Tibet. (Haven’t I spent a few nice days walking around Barcelona in my time? Didn’t Air Genius Gary Leff get a decent meal at El Bulli? Didn’t they once make a young people’s movie about the place in which no one has to do any work?) Don’t we have bigger problems to worry about? How easily does he think negotiations for separation can go, especially with entire eurozone deals at stake and a Spanish history of sending in troops? He mentions that the territory is subjected to «humillación constante» de España. Maybe he’s been misquoted, but from what I see I take this as a paradigm example of how a really smart person can be taken in by rather primitive tribal arguments.
The discussion in the comments is surprisingly rational, with no shortage of people pointing out that maybe culture and language matter more to people than the mathematical models of rootless cosmopolitan economists. Nobody's even used the "R" word yet; contrast that with what you hear when secession is raised in the US.