In the case of such a broad surveillance system, I'm having trouble coming up with good secret reasons. Perhaps I'm being unimaginative. If, for example, this system was preventing hundreds of terrorists, what damage would be done by stating that it has unequivocally stopped major threats?

What's the damage in revealing what's going on and why?

Is the plan "if we're quiet enough, bad guys won't bother using encryption or cover their tracks?

I'm curious to know, what information, in theory, would change someone's opinion, and must remain secret in order to keep things safe. Aside from breaks on popular ciphers or mass collusion with major hardware/software vendors.

Edit: I'd trust a president stating for sure that this is entirely necessary, and stating there is secret information that'd even change the EFF's opinion. Obama's speech doesn't give that perception at all. It feels like he's stumbling around to justify something he knows is bad, using nebulous threats.

I think Obama is somewhat conflicted over the balance and is unable to reveal the interesting parts of that question.

Assuming an environment where all digital information is monitored and it actually is used in a reasonable way (active, investigations, internal warrants from courts, etc.) I could see there being an argument that keeping the extent of it secret prevents people from knowing what's being monitored and avoiding those methods of communications. I don't agree with this argument primarily because things change in leadership and governments and having a system like this (especially with it being secret) can lead to abuse.

This was Snowden's point about changes in policy and 'turn key tyranny'.

Clearly access to this information changed Obama's opinions pretty severely - there must be a lot we don't know.

What if it had prevented a biological weapon that could have killed millions of people in NYC? Revealing this publicly could cause mass panic.

Obviously I have no evidence of something like this, but it's a thought experiment to consider. Would that make the surveillance worth it in your mind?

The thing is, I don't think anyone is claiming major successes. They're just saying that it's OK. Watching Obama's talk just gives you the feeling it's political nonsense, with a bit of CYA lines too.

The catch-22 you've described is why it's so important for as little to be classified as possible. When secrets are kept from the people who those secrets are intended to protect, it is impossible for the people to know and debate their value. It creates two classes of people: ordinary people, and their rulers who possess this special information.

This is why even a vague societal acceptance of the idea that safety requires sacrificing certain rights is exceedingly dangerous. It creates a slippery slope where the people make progressively greater sacrifices to the "cleared" class so that, according to that same class, they can protect the people. But the people never know if they were safer. All they know is that they gave up rights for a promise that may or may not have been kept.

I'd like to think I would, but it's hard to define ideas when you're missing huge pieces of information.

Yet, we're at a point that the boogey-man of 'terrorism' has made us throw that away for the concept of safety.

Yes, I'm absolutely certain that if you're in the position to protect people and enforce the laws that its rather nice to be able to do anything to make that happen- but we've just got to accept some level of risk (and hazard) in exchange for them not violating everything just to create that risk-free perception.

That's one way to put it but it seems like a jarringly bad way. Secrecy is such powerful force that we shouldn't bluntly say it has a corrupting, corrosive and poisonous effect on our society? I disagree. It is so powerful we should say that.

Sorry if that's too simple or something