> For example, if you had a system that could scour through essentially infinite amounts of hay and be able to spit out each brown needle that passed through (think keyword filters), then definitely you'd want all the hay you could find, and then even more hay.
It doesn't work that way. In a big system with too much diversity, anomalies become indistinguishable from noise and you cannot eliminate noise. This translates in so many false positives that (1) the security agencies will end up spending their resources on investigating innocents and (2) a lot of innocents will suffer from being discriminated, investigated and even tortured.
And another thing - it's a commonly known fact that security agencies have the means to listen and to record phone conversations, ever since the phone was invented. If anything, a would-be bomber would have to be pretty dumb to speak about his actions on the phone or to send unencrypted messages over the Internet. If this stuff still happens only speaks to their level of sophistication, but training on the matter can render whatever "smart filtering" you have useless.
It doesn't work that way. In a big system with too much diversity, anomalies become indistinguishable from noise and you cannot eliminate noise. This translates in so many false positives that (1) the security agencies will end up spending their resources on investigating innocents and (2) a lot of innocents will suffer from being discriminated, investigated and even tortured.
And another thing - it's a commonly known fact that security agencies have the means to listen and to record phone conversations, ever since the phone was invented. If anything, a would-be bomber would have to be pretty dumb to speak about his actions on the phone or to send unencrypted messages over the Internet. If this stuff still happens only speaks to their level of sophistication, but training on the matter can render whatever "smart filtering" you have useless.