On what is and is not an argument about Ricardian Equivalence (long and wonkish, but politically relevant)

Further to the issue I raised in my last post, Krugman has responded to the criticism David Andolfatto (referencing myself and Stephen Williamson) offered. Krugman notes that his original claim was the somewhat bold one of accusing Lucas (another Nobel prize-winner) of not understanding what Ricardian Equivalence is (the charge that Williamson, Andolfatto and I [...]