Mathematician John Allen Paulos on party games and FISA:

In [Daniel] Dennett's more interesting and suggestive game, one person, the subject, is selected from a group of people at a party and asked to leave the room. He is told that in his absence one of the other partygoers will relate a recent dream to the other party attendees. The person selected then returns to the party and, through a sequence of Yes or No questions about the dream, attempts to accomplish two things: reconstruct the dream and identify whose dream it was.

The punch line is that no one has related any dream. The individual partygoers are instructed to respond either Yes or No to the subject's questions according to some completely arbitrary rule. Any rule will do, however, and may be supplemented by a non-contradiction clause so that no answer directly contradicts an earlier one. The Yes or No requirement can be loosened as well to allow for vagueness and evasion.

The result is that the subject, impelled by his own obsessions, often constructs an outlandish and obscene dream in response to the random answers he elicits. He may think he knows whose dream it is, but then the ruse is revealed to him and he is told that the dream really has no author. In a strong sense, however, the subject himself is the dream weaver. His preoccupations dictated his questions which, even if answered negatively at first, frequently received a positive response in a later formulation to a different partygoer. These positive responses were then pursued.

What's that got to do with warrantless surveillance? Faced with random stores of information, investigators will feel driven to tease out a narrative. The wider the net, the more fertile the ground for storytelling: Delusion will be rewarded, biases confirmed.

Having so much unfiltered information (phone records, emails, internet searches, travel itineraries, financial statements, Facebook postings, credit card bills, etcetera) with which to work and having no requirement for specific focus or judicial warrant, any wild hunch or obsession can be pursued relentlessly without fear of disconfirmation.

The resulting combinatorial explosion of connections and interconnections will always provide ample raw material for the development of any investigative group's pet theory. If, for example, there are 400,000 Americans (and a million names) on the terrorist watch list, as the ACLU announced last month, then there are about 80 billion pairs of possible co-conspirators on the list and more than 10 quadrillion possible threesomes on the list. Search this large "party" diligently enough for confirmatoryYesses and ignore willfully enough disconfirmatory Noes, and who knows what will result.

Via Matt Steinglass, who has more.