I think it is super important in the current debate about government surveillance to separate two different arguments. First, I have stated and continue to believe that large scale secret programs without supervision and without checks and balances are unacceptable for a democracy. The potential for abuse and the cost in terms of a loss of rights (eg having a fair trial) are simply too large.
Second, we should, however, not make the mistake of applying what Taleb would call a turkey argument to the severity of threat of terrorism: the turkey believes for a long time that the farmer doesn’t pose a threat. For instance, this piece in the Atlantic points out that from 1999 to 2010, about 3,000 people in the US were killed by terrorists compared to 364,000 by gun violence. True. But a single nuclear bomb detonated in Times Square would dramatically shift that balance. And there are very likely people out there in the world trying to figure out how to do just that.
So the debate we need to have as a society is what kind of more limited and properly supervised programs we are willing to accept to try to prevent such an event from occurring. The answer may still be only a very restricted set but we should not be kidding ourselves about the severity of the threat based on a false reading of statistics.