"Characters can be ignorant, but the author can't say the three magic words 'I don't know.'"

One funny exception to this is Mark Twain's "A Medieval Romance," which you can read here:

http://www.readbookonline.net/readOnLine/1537/

Just scroll down and read the last three paragraphs.

Eliezer's nothing-but-applause-lights speech sounds strangely like every State of the Union address I've ever heard...