This is not a very 'Tumoriffic!' update. My health is fine right now. This is about current events. It is not an exhaustive or radical post, just an analogy that occurred to me as I considered doing a particular test on a patient.
There is such a thing as too much information--too much of the wrong kind of information, or information too dearly bought. This is true in medicine, and I believe it is true in national security.
Beginning in the late 1800's, burgeoning technology granted us more and more power to image and measure the body as never before. The number of screening tests ballooned. One might assume that the that early detection--more information--would automatically lead to fewer deaths and less misery. That is not always the case.
Similarly, technology has granted our government power to monitor private individuals as never before. The advocates for this technology believe that it will automatically lead to fewer deaths and less misery.* I am skeptical. I think it is human nature to overestimate benefits and underestimate risks of new technologies in all fields. National security should learn from medicine.
Sometimes, information can lead us down destructive paths. We used to test every middle-aged man's PSA instead of limiting the test to those at high risk. Unfortunately, most men with a high PSA did not have prostate cancer, most prostate cancers would not grow fast enough to impact lives, and treatments were (an are) risky. For every 1,000 we tested, we terrified over a 100 with a 'positive result.' The resulting biopsies and treatment left 29 of those men impotent and 18 in diapers. They gave two men heart attacks, and one man a blood clot in his lung. One man may have died due to the treatment, and one man might have lived longer. (http://www.cancer.gov/cancertopics/factsheet/detection/PSA) The PSA test gave us more information, but we did not know what to do with it.
In medicine, we gloried over the supposed prostate cancer deaths averted and did not see the harms. In national security, they tout the terrorist plots foiled, but, inevitably, innocents are harmed. (e.g., http://www.portlandcopwatch.org/PPR34/PJTTF34.html, and http://www.humanrightsfirst.org/our-work/refugee-protection/refugees-falsely-accused-of-terrorism/page/2/)
Sometimes, the very act of gathering information is harmful. For at least 70 years after the invention of the x-ray, doctors routinely x-rayed pregnant women to image the fetus and evaluate the pelvis to plan delivery. As first publicized by British physician Alice Stewart in 1958, this could increase the child's risk of cancer by a factor of ten. The x-ray may have prevented some delivery complications, but it caused millions of cancers. (http://www.ratical.org/radiation/KillingOurOwn/KOO6.html) The NSA's inquiries are showing harms much more quickly. (e.g., http://www.reuters.com/article/2013/11/13/us-usa-security-hearing-idUSBRE9AC0S720131113, http://legalinsurrection.com/2013/11/lavabit-founder-i-had-effectively-lost-the-ability-to-control-my-own-network/, and https://www.aclu.org/blog/national-security/you-may-have-nothing-hide-you-still-have-something-fear)
These are but a few examples. In national security as in medicine, technology has given us powers once only attributed to gods. It is natural to want to use them to try to prevent all of the disease or evil in the world. Sometimes, however, the prevention is worse than the disease.
* Note that I am not going into questions of motives. Instead, I am taking as a given that most in the medical profession want to heal, and most in national security want to protect.