I grew up voraciously reading mystery novels, with Agatha Christie being my author of choice, with other mystery writers thrown in from time to time. She was a prolific writer and I suspect that I have read at least 90% of her output. Hence my ideas about the conventions of that genre have largely been shaped by her books.
One of the cardinal rules was that the author had to play fair by the reader. There had to be a rational solution to the mystery that fitted the facts that had been presented. No magic and supernatural elements were allowed. The author was allowed to plant fake clues to lead the reader astray (and we in fact expected it) but there could not be facts that contradicted the solution.
I extend this expectation to everything that constitutes a puzzle or mystery, such as mystery films.
I recently watched the 2005 French film Cache (the English title is Hidden) starring Daniel Auteuil and Juliette Binoche. It is a slow-moving suspense film. The central plot is that a family consisting of parents Auteuil and Binoche and their 12-year old son suddenly start receiving videotapes on their doorstep that seem to be taken from a hidden surveillance camera pointing at the front of their house and thus captures their comings and goings. Later on, the tapes arrive wrapped in paper that has crude drawings in crayon of blood spurting from the necks of people and chickens.
Needless to say they become worried by this stalking and the film is about the toll it takes on them as they try to figure out who is doing this to them and how and why, although Auteuil has reason to suspect that it is something that had its origins in his childhood.
The film never answers those questions and the viewer is left at the end trying to figure it out. Film critic Roger Ebert in an initial review highly praised the film and then later did an extremely close, almost frame-by-frame, analysis of it trying to solve the puzzle, and suggests various possible solutions but points out that none of them are satisfactory since every postulated one has problems in that some fact seems to contradict it. He says that the film director Michael Haneke seemed to delight in the fact that people could not solve the puzzle. Haneke even has a closing scene that is important but he shoots it in such a way that apparently over 50% of viewers missed entirely (as I did) a key interaction between two people, because they were at a distance and at the edge of the screen while other figures were moving around in the central foreground. Haneke was supposedly pleased that so many people missed it.
I found the film highly unsatisfying for those reasons. I enjoy solving puzzles. But human-created puzzles (crosswords, Sudoku, jig-saw, and the like) are constructed according to rules that guarantee a solution and only the skill of the puzzle-solver stands in the way of a solution. It is easy to construct a puzzle that has no solution but who would bother to attempt it?
It is similar to scientific research. With the puzzles of nature that form the basis of scientific research, one assumes that a solution must exist and that the only thing that prevents one from finding it is insufficient information or cleverness. One is certain that one is not being deliberately misled. Einstein expressed this sentiment famously as, “The Lord God is subtle but malicious he is not” but since religious people can never get it into their head that Einstein was using god as a metaphor, I prefer his alternative formulation of “Nature conceals her secrets because she is sublime, not because she is a trickster.”
Since books and films are human creations, the same rules should apply. In my opinion, if a film poses a puzzle, then it should contain a solution that can be figured out. It is not necessary that everything be nicely wrapped up and tied with a bow at the end. It could have alternative explanations that are each plausible, such as in Rashomon or a film could be constructed in a way that it is hard to reconstruct the sequence of events, as in Memento. Those are allowable and in some cases desirable if you want to leave people with the idea that sometimes we just cannot figure out the solution to a puzzle because of insufficient information.
It is also different with questions of meaning and motive because those are inherently ambiguous and possibly unknowable and people often do act out of contradictory motives. A film that leaves you guessing about the whys is fine. But to make the actual facts of the events such that no solution is possible seems wrong to me.
But a filmmaker should not insert facts that preclude anyone arriving at any answer at all because each one is confounded with a contradictory piece of information. To do so is to reveal the filmmaker as a ‘trickster’. I refuse to waste time trying to solve such fake puzzles and think of it as a betrayal of trust between the filmmaker and the audience. I suspect that Cache falls into that category though I am willing to be proven wrong. So while the film was interesting (and Binoche in particular gives a fine performance) it left me feeling dissatisfied and even cheated.