Edward Snowden points to a different danger of such secret data accumulation:
Well, I'll add this. For those of you unfamiliar with concepts of penal architecture, the Panopticon was a proposal by the 18th century philosopher Jeremy Bentham. No true Panopticons were ever constructed for reasons of technical difficulty. The nearest thing to a true Panopticon was built in Cuba in the 1920s:[Snowden] said the [analysts and governments] labored under a false premise that “if a surveillance program produces information of value, it legitimizes it. . . . In one step, we’ve managed to justify the operation of the Panopticon.”The Panopticon is a architectural concept for a prison where the guards can watch, unseen by the inmates, from a tower in the middle into all cells build in a circle around the tower. It leaves the inmates in a perceived state of permanent surveillance. The French philosopher Michel Foucault described the effect:
Hence the major effect of the Panopticon: to induce in the inmate a state of conscious and permanent visibility that assures the automatic functioning of power. So to arrange things that the surveillance is permanent in its effects, even if it is discontinuous in its action; that the perfection of power should tend to render its actual exercise unnecessary; that this architectural apparatus should be a machine for creating and sustaining a power relation independent of the person who exercises it; in short, that the inmates should be caught up in a power situation of which they are themselves the bearers.The original Panopticon, like the digital version the NSA is building, takes away all feeling of privacy. Even when one is not watched, knowing that the possibility of being watched is always there, creates uncertainty and leads to self disciplining and self censorship. It is certainly a state the powers that be would like everyone, except themselves, to be in.
ironic postscript from Wikipedia:
[T]he essential elements of Bentham's design were not only that the custodians should be able to view the prisoners at all times (including times when they were in their cells), but also that the prisoners should be unable to see the custodians, and so could never be sure whether they were under surveillance or not.
This objective was extremely difficult to achieve within the constraints of the available technology, which is why Bentham spent so many years reworking his plans. Subsequent 19th-century prison designs enabled the custodians to keep the doors of cells and the outsides of buildings under observation, but not to see the prisoners in their cells. Something close to a realization of Bentham's vision only became possible through 20th-century technological developments – notably closed-circuit television (CCTV) – but these eliminated the need for a specific architectural framework.