I think there's some truth to Mankiw's observations. What he doesn't say is that both the right and the left are way wrong. Both political sides have implicitly rejected Austrian economics, which I find to be far more accurate in representing reality. I say "implicitly" because I've yet to meet a right-winger or left-winger, per the descriptions Mankiw offers, who has demonstrated even a hint of understanding of Austrian economics; they can't explicitly reject that which they do not know.

Wanna know why the U.S. is so screwed up economically (and will continue to get worse)? It's because both factions of the Republicrat Party use essentially the same, wrong models of economics, differing only in degree.