Bad Economics/Economists: Right Diagnosis, Wrong Prescription

My friend Alan Nelson recently posted a link on facebook to the following article: http://www.nytimes.com/2014/03/23/business/economic-view-when-the-scientist-is-also-a-philosopher.html with an appropriately snarky note that the author, N. Gregory Mankiw (the Chair of the econ department at Harvard, natch), seemed to be arguing that the only changes to the status quo permissible are those that are verifiably Perato efficient improvements.  An obvious corollary is that, since every reasonably substantive and complex policy change will have winners and losers, we should never change policies at all.