In the Doctor Who episode "Blink", the Doctor has a one-way conversation with a video camera, reading off of a script. The script would have been written some years later by someone watching the video that the Doctor recorded. The person, Sally, watching the video years later wonders how the Doctor knew what to say, and the Doctor advised her to look to her left, viz at the transcriptionist. How did the Doctor know the transcriptionist was to Sally's left? Well, obviously, because the transcription said as much:it had the Doctor saying "look to your left", and he was reading it while recording the video.
I don't see any logical problem with this: at the time of the videography, the Doctor was reading a preexisting script, and at the time of the transcription, the transcriptionist was transcribing a preexisting video.
The problem arises if one posits that every bit of information one has must have a source. In that case, a source seems to be lacking for the Doctor's knowledge of the transcriptionist's being to Sally's left: he got it from the transcription, which got it from him, so there's no root source at all.
(I seem to recall the same problem arising in the book The Time Traveler's Wife, by Audrey Niffenegger. However, I read it some years ago and am not sure — and certainly don't remember the details.)
So my questions are several:
- Do any sources from the sci-fi/fantasy world discuss seriously the issue of how the Doctor knew something only known from his own transcription, or the corresponding problem in other sci-fi/fantasy works?
- Do any philosophers (or information-science people perhaps) propose a rule along the lines of "every bit of information must have an original source" (or its negation)? (This would have nothing to do with time travel, and is of independent interest.)
- If so, do any sources connect that to the issue that I raised, which arises in sci-fi/fantasy works?