Analyses of national indebtedness invariably leave out an important set of factors, says Dalrymple: national culture and history:

Greek ‘prosperity’ had been based almost exclusively on borrowing, and by the government at that. It was for current consumption alone. Moreover, to compare the dysfunction of the Irish government with that of Greece would be absurd; it would be like comparing a bee to a crocodile.

I have no idea what weight exactly should be given to political, cultural and historical differences, but I think it is mad to ignore them.