From German geist or Dutch geest ("spirit"). The supposed life-essence or consciousness of a person, surviving bodily death and still present in some way in the physical world. The belief assumes that the physical body and the soul, or life-principle, are separate entities and that the soul survives physical death. ("Ghost" in this case is defined as a disembodied spirit able to physically manifest, rather than as just another term for "spirit.").
Belief in ghosts is among the most ancient and universal of all paranormal beliefs, although there are innumerable cultural variations on exactly what ghosts are and why they appear. In traditional European belief, a ghost is the conscious spirit-essence of someone who has died. The spirit may be unable to go on to spiritual realms because of unfinished tasks on Earth or his refusal to accept his own death.
In Chinese and other Oriental belief, a human being has two souls, the divine soul or true living essence, which returns to the spiritual realm after death, and the kwei or earth-soul, which remains on earth and eventually fades. The earth-soul isn't the essence of the person but a sort of crude copy or mimic. It may become a hungry ghost and prey upon the living.
Some parapsychologists postulate that at least some ghosts aren't spirits but "impressions" left behind by a person while alive or at the time of death, especially a traumatic death. Most ghost phenomena, these researchers note, are repetitious and purposeless, more like video or audio recordings.
Ghosts, according to the belief, can manifest to any and all the senses. A ghost may present itself as an image, sounds, odors, tactile, feelings of cold, a feeling of intruding presence, or any combination of impressions. Or the ghost may move physical objects and be called a poltergeist ("prankish spirit"). Some parapsychologists consider ghosts and poltergeists separate phenomena.
Parapsychologists have hypothesized that ghosts may become temporarily visible by (1) absorbing matter or energy from their surroundings, often from a living person, who may complain of feelings of cold as the ghost drains heat energy from him, or (2) "appear" to the viewer by stimulating the visual centers of the brain in some unknown fashion. In this case the viewer experiences what amounts to an hallucination, but its ultimate source is outside him. Animals, with senses more acute than man's, are supposed to be able to see or sense the presence of ghosts, even if humans on the scene sense nothing unusual.
Folklorists generally distinguish two types of mythical ghost, the spectre-ghost or apparition, frightening but harmless, and the hungry ghost, which actively preys upon the living. Vampires are a form of the hungry ghost.
Even today in the industrialized world, belief in
ghosts and hauntings, or at least allowing their
possibility, is widespread and held by many people,
including the educated.
The problem with ghosts is similar to that with UFOs: thousands of testimonials but no proof or even reliable evidence of their existence. Proving or disproving the existence of ghosts as true paranormal entities is difficult, amounting to trying to show the existence or non-existence of things that may or may not exist in a material sense.
Psychical researchers have offered what they consider evidence in the form of photographs, videos and sound recordings, but none of these are convincing and all would be easy to fake. Other known phenomena can explain ghosts. People may hallucinate or misidentify, influenced by wishful thinking, grief and loneliness. Who hasn't wanted a departed loved one to show in some way that he/she is still alive and conscious in some way?
Someone who vividly dreams of a departed person can be convinced that he has indeed been visited by the soul of a loved one. Another possibility here is hypnagogic or hypnopompic "dreams," or "lucid dreams," so vivid and lifelike that the dreamer may not be able to distinguish them from the objectively real. There is also the phenomenon of what could be called the construct hallucination or dramatized hallucination wherein a person, often under extreme stress, hallucinates a vision of an encounter from a departed loved one or some other supernatural being, often comforting or giving advice. These experiences are loosely called "visions" and seem to be elaborate dramatizations concocted by the unconscious mind of a traumatized person to lend him or her reassurance and a sense of validity in order to help resolve a major difficulty.
The numerous accounts of ghost encounters, the vast amount of literature on the subject, and the difficulty in proving or disproving the individual accounts help keep the belief alive.
(From many sources and accounts)