Greenspan and Tax Cuts
I agree with Atrios and Krugman that Alan Greenspan's behavior relative to the 2001 Bush tax cuts was irresponsible and that his efforts at self-exculpation are unconvincing (BDL is too kind here). On the other hand, I don't think it makes a ton of sense to attribute vast causal powers to Greenspan's testimony on this regard.
The tax cuts passed because (a) the GOP was monomaniacally focused on reducing income tax rates for rich people, and (b) a shocking number of Democrats from red America seem to have felt that this, rather than some symbolic cultural issue, was a good topic on which to surrender. Obviously, if Greenspan had transformed himself into a technocracy-oriented social democrat and denounced the Bush economic agenda from the rooftops, that might have made a difference, but piping up more clearly as a small-government advocate of spending cuts and balanced budgets wasn't going to swing this thing around.