In all my life I have met only one person who claims to have seen a ghost. And the interesting thing about the story is that that person disbelieved in the immortal soul before she saw the ghost and still disbelieves after seeing it. She says that what she saw must have been an illusion or a trick of the nerves. And obviously she may be right. Seeing is not believing.
Unlike C. S. Lewis, I’ve never met anyone who’s seen a ghost. I don’t automatically believe ghost stories. But I don’t automatically disbelieve them, either. Nor do I reflexively write off stories of possessions, visions, miracles or other creepy stories of the paranormal.
Context is everything. I can disbelieve in orcs because I know J. R. R. Tolkien made them up for his epic universe. I can disbelieve in Martians because we know Mars to be inhospitable to all but the simplest organic life. I can disbelieve in the Flying Spaghetti Monster because it was some wiseass college kid’s attempt to poke fun at religious beliefs while questioning the need to present intelligent design in school curricula.
But we have no such context of knowledge which makes ghosts or demons inherently impossible … or even unlikely.
There have been many attempts to scientifically prove natural explanations for paranormal phenomenon. It’s almost too easy to disprove UFOs or spiritual mediums; Lord knows there have been a supertanker-full of hoaxes and magicians’ tricks foisted on the credulous by mountebanks looking for a laugh or easy money. (Can anyone say “Uri Geller”?)
But when it gets down to brass tacks, lab experiments generally fall apart either because the scientists get the metaphysics wrong or because the experiment assumes what needs to be proven.
An example of “getting the metaphysics wrong”: A few years ago, a psychologist claimed to have proven the soul doesn’t exist because the experiment had shown where in the brain the will to act originates. However, Christians have never claimed that there was any separation between body and soul; assuming that a soul willed something, it would make sense that that command would show up somewhere in the brain. So the experiment only proved that the scientist didn’t really know what he was testing for.
An example of scientific question-begging: Even more recently, another scientist claimed to have proven that ghost sightings result from the mind imposing a pattern on random bits of information. His team had found that people who see more patterns in a series of images than were actually present had a surplus of a particular chemical. However, his team also found that some people saw fewer patterns than were presented; when examined, the “skeptics” were found deficient in the chemical the “believers” possessed in abundance. As interesting as the results are, the scientists failed to prove first that ghosts don’t exist.
The importation of materialist, determinist expectations into such experiments is the rock on which science constantly founders. It’s a joke among biologists that “under rigidly controlled environments of water, food, light and temperature, the organism will do as it damn well pleases;” so will God. An extract from the science humor magazine The Journal of Irreproducible Results shows the difficulty of forcing God into the lab:
In the case of the Cherubim and four Archangels, the experimenter noted that the reward [a 3 gm Noyes unleavened pellet] would disappear while the S was in the start box. It was thought at first that some rats were loose in the laboratory. However, none were found and one assistant advanced the hypothesis that these occurrences illustrated that angels are not confined by time. …It is possible that the methods used in this study were inappropriate for angels and need modification. It is possible that, rather than attempting to teach angels a right-left habit, an up-down or a right-wrong habit may be more suitable. In addition, the reward may have been unsuitable. Perhaps the Ss could have been motivated by depriving them of the sight of God and the reward could have been the sight of God. Our laboratory technicians are presently working on a solution to this problem.
Far from being limited to splashy, inexplicable miracles, God is perfectly capable of interfering with His cosmos in ways indistinguishable from ordinary, natural means, even using probability in His favor.[*] For much the same reason, since at least 1853 the Church has insisted that priests consult with health professionals to definitively rule out natural illnesses of mind and body before proceeding with an exorcism. Yet, as Fr. Gabriele Amorth writes, demons occasionally can be tricked into revealing their presence … for example, by blessing an article of clothing without the possessed person’s knowledge.
One other objection exists. It’s a fact that individual priests and bishops have used the threat of Hell and Satan to coerce behavior. But it doesn’t follow from that fact that Satan doesn’t exist. Abusus ad usum non tollit (wrong use does not preclude proper use). There is one sure way to find out whether Satan exists: just keep f***ing up!
“There are more things in heaven and earth, Horatio, Than are dreamt of in your philosophy” (Hamlet, 1:5). I submit there’s a difference between not giving every report of paranormal phenomena the full weight of one’s credence and the knee-jerk disbelief of all such reports that’s often mistakenly called “skepticism”. Belief in the existence of immaterial beings and an immaterial dimension (if you will) to nature doesn’t contradict the material nature of the universe Man experiences and Science explores; perhaps, someday in the distant future, Science will be able to include the supernatural in its study of Nature.
Until then, I’ll cheerfully concede the existence of ghosts, even if the only ones I see show up for their ritual bribe of candy on October 31st. “Blessed are those who have not seen and yet believe” (Jn 20:29).
Besides, to be completely candid in the matter, I really don’t want to find out firsthand that ghosts do exist. I’ve had enough terrors for one life.
[*] The law of probability, I contend, proves that God has a sense of humor.
 Lewis, C. S. (1960). Miracles. New York: Touchstone/Simon & Schuster, p. 9.
 Lester, D. (1983). The learning of a simple maze habit by angels. In G. H. Scherr (Ed.), The Best of The Journal of Irreproducible Results (pp. 190-191). New York: Workman Publishing Co.
 Amorth, G. (1999). An Exorcist Tells His Story. San Francisco: Ignatius Press, p.120.