There are many varieties of "ghost" story, and not all ghost stories are about ghosts. The reality of ghosts cannot be separated from psychology, as they are "psyche" phenomena regardless of any independent existence that they may or may not have. I read Lord Dunsany (Edward Plunkett)'s story "Ghosts" last night, based purely on the title. Dunsany was part of the Abbey Theatre circle in Dublin, and was friends with many of the great literary figures of his time. He was related to Oliver Plunkett, the sainted Bishop of Armagh, and was friends with the likes of W.B. Yeats and Lady Gregory. The story is about a house in Oneleigh, where the narrator visits his brother and has a quarrel with him. The house has all the traditional "haunted house" elements, with the howling winds outside, dark corners, and deathlike stillness in certain parts of the house. There is of course a "door that hasn't been opened", and "spiders watching by the deathbeds of yore". In short, the house is a troubled psyche, and the room is an entrance to the collective unconscious, where we encounter long-forgotten history.
In this room, the narrator sees spirits, and near them dogs that represent their sins. The dogs take notice of him, and circle around him, and their influence preys on his weaknesses, and gives him the urge to kill his brother. So, now we are dealing with the Shadow--and the Shadow is always the first archetype encountered on such a journey. He chooses dogs as his symbol, and "dog" is certainly the reverse of "god". One might also think of the hounds of Hell, or Cerberus at the gates of Hades. Nonetheless it is a confrontation with his own darkness, and his undeveloped emotions.
Our narrator then begins to do a geometric proof. When he completes the theorem, all of the ghosts melt away, the room is empty, and he realizes the absurdity of killing his brother. Rationality and logic dispel the demons of the unconscious. A rather tidy ending, and an interesting way of trying to synthesize rationality and irrationality.
But is this really a synthesis? It plays up to the belief that we've held since at least the 19th century, that Reason will triumph and all old ghost stories and superstitions will just disappear in a puff of smoke. It is good that the narrator has talked himself out of murdering his brother rationally. But the ghosts don't really disappear. They may go away for the time being, but they will always reappear. Even in the Gigantomachy of Greek mythology, Zeus battles Typhon, the dragon, but doesn't actually kill the dragon--he simply banishes it to the depths of the Earth. The brighter our light shines, the darker our shadow behind us. These things don't go away, and the idea that Reason will conquer all is as absurd as thinking that paying for indulgences will get you to "Heaven".