John Allen Paulos in his excellent Who’s Counting column at ABC News:
Thinking about the genesis and consequences of the Iraq War and the recently passed Foreign Intelligence Surveillance Act (FISA) that authorizes wholesale wiretapping, I recalled a relevant party game I once wrote about. The game, described by philosopher Daniel C. Dennett in his book “Consciousness Explained,” is a variant of the familiar childhood game requiring that one try to determine by means of Yes or No questions a secretly chosen number between one and one million.
In 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.
More here.