I came across the claim that sir Arthur Conan Doyle didn't write the Sherlock Holmes stories and probably just, at most, edited them.
Normally such a claim would not be taken seriously. But the person who made the suggestion was Martin Gardner, an hero to many skeptics and a debunker of many ideas in pseudoscience and the paranormal. For those who are too young to remember him, he was the author of the Mathematical Games column in Scientific American for several decades and a leading skeptic and science writer (see bio here).
In an essay included in his book Science Good, Bad and Bogus published in 1981 he argues that the rational and scientific character of Holmes could not have been produced by a character like Conan Doyle. Conan Doyle was a credulous believer in spriritualism and fairies and a careless observer of psychic demonstrations. He was such a believer that he refused to believe that Houdini was performing tricks and not real magic even after Houdini denied being a psychic.
I doubt Gardner's argument as it seems to be based purely on what someone is capable of imagining. So my question is is there any other reason to doubt that he wrote the stories and invented the character?