I think Mass Surveillance is a bad idea, extremely high risk and the potential for abuse is high.  I also think that it consolidates too much power in one place which is dangerous for the future and the secrecy is a big problem.<p>That said there is an obvious use for it in helping stop attacks and pretending there isn&#x27;t is weird to me.<p>&gt; show me one incident, just one where government surveillance has helped stop a terrorist attack and I&#x27;ll be all in for your surveillance<p>Whether or not these exist they&#x27;re likely to be classified, it&#x27;s possible attacks have been stopped - the classification of information makes it hard to know.<p>Though mass collection can help, if you have intel of suspicious people you could look through the entire history of their communication - see what they&#x27;ve been saying and to whom.  When you newly learn that a person is a part of ISIS (for example) you can look through their entire communication stream retroactively.  Since the attackers are not always that sophisticated (they used SMS in Paris like you said) you can potentially learn a lot of information by doing this (their network, maybe plans).<p>They&#x27;re posting videos of themselves on youtube showing off weapons and locations - I suspect there&#x27;s a lot of information available in their communication that&#x27;s useful for stopping attacks.  It&#x27;s a tool you would obviously want if you had to do the job.<p>That said I think the secrecy is dangerous because it prevents the public from being able to determine what level we&#x27;d accept (and legal recourse against abuse).  It also is more likely to encourage abuse and since James Clapper lied to congress about it we can&#x27;t trust the organizations that have tasked themselves to do it.