Shell Game (short story)
"Shell Game" is a science fiction short story by American writer Philip K. Dick. It was submitted to the Scott Meredith Literary Agency and received by SMLA on December 12, 1953. It was published in "Galaxy Science Fiction" in September 1954 Plot summary. A group of paranoid mental patients, long stranded on an alien planet by shipwreck of the robot controlled hospital spaceship transporting them to a mental hospital, believe themselves to be constantly under attack by aliens or Terrans. They discover the damaged ship in a bog, and from recorded tapes they learn their condition  and the circumstances of the shipwreck. Even when they discover this evidence of the truth and attempt to verify or disprove the information on the ship's tapes, they construct sophisticated explanations to explain the "attacks" as a plot by the enemy who they now regard as definitely Terrans. After much internal dispute and sometimes violent conflict at the end of the story the survivors of the infighting are unsure if they are paranoid or victims of a plot. As one of them states they are like rulers who are all 12 or 13 inches long so have no basis  for comparison. The central question of this story is how would people determine whether their judgments are reasonable or unreasonably paranoid when they agree they have evidence that all or none of them are, in fact, paranoid. This story was later expanded in the novel "Clans of the Alphane Moon". Copyright status. Shell Game" is still under United States copyright protection. "Shell Game" appears in the following Philip K. Dick collections: