Peter Shaffer's play Amadeus and its film adaptation by Milos Forman were similar exercises which played with ideas based on limited historical knowledge. If you had been there, in Mozart's time, you'd know they got it all wrong, but none of us had.
Fiction, even fiction that "plays with ideas" starts out by observing history and then filling in the author's ideas. But twisting historical events and the nature of organizations that are still with us? Opus Dei a buncha murderous thugs? No thanks, Danny boy.
Those are interesting questions outside of this discussion and they're covered in a thin book by Umberto Eco Six Walks in Fictional Woods, which is a collection of his university lectures, I think. Highly recommended.
Interesting Cat. I like Eco and I may look for that collection. Thanks.
And you make a good point about Amadeus. (Almost makes me question my opinion on these issues : ) .
If you mean that if the author twists the facts too far the novel will not be believable and therefore not readable, I agree. If you mean it's improper or unethical for the author to do that, I disagree. I mean, an author could write a book about Abraham Lincoln's experiences in World War II right? Why not? Go right ahead. Of course, it's doubtful whether anybody would be interested in reading it.