I’ve started reading Arthur Conan Doyle’s Sherlock Holmes stories for the first time since I was a teenager, and I realize now that in one of the stories’ most characteristic scenes, Doyle cheats.
A visitor calls on Holmes and Watson. Holmes instantly deduces the visitor’s occupation, social background, and other important facts, amazing the visitor and Watson — and, presumably, the reader.
But Doyle doesn’t let the reader see the minutiae from which Holmes makes his deductions. We readers see the situation via Watson, who (as Holmes loves to point out) doesn’t notice small but crucial details. If Watson doesn’t report a telltale stain on the visitor’s glove or a revealing scuff on her shoe, we can’t know that it’s there until Holmes says so.
And here I thought that playing fair in mystery stories means letting the reader see the same clues as the detective.