it's hard to evaluate the claim that the nsa surveillance program has prevented attacks, and it's the sort of case where people have such obvious and powerful motivations to lie, distort, etc. that you'd be silly believe them without evidence. now on the other hand, the complete assurance of greenwald, snowden and others that the program isn't effective against terorism at all is at least equally hard to assess. but here's my view: i think we're at that choice point. i would take somewhat more terrorism in preference to universal oppression of the sort created by the nsa.
it's often said that the first duty of an american president is to keep americans safe. no, you sweet little kindergartner, that's the first duty of your mommy. the first duty of the american president is to keep americans free.