Possibilities

I was watching a trailer for an old movie where someone quoted the famous Sherlock Holmes line: "when you have eliminated the impossible, whatever remains, however improbable, must be the truth."

It's from The Sign Of The Four, if you're wondering, and is probably Conan Doyle's most quoted line. (He never wrote "Elementary, my dear Watson.")

I have to admit it's logically sound, but in practice unworkable. Eliminating all possibilities in the real world is quite a task. Even eliminating the likely explanations is beyond most people.

So deduce away, Sherlock, but it's better to figure out what happened through positive proof than a lack thereof. It's too easy to fool ourselves into believing we've eliminated all other possibilities. (Imagine watching a magic show and, when you can't figure out how the trick is done, concluding it must be magic.)