The power to perceive things that are out of the natural range of human senses. Usually associated with precognition, the psychic knowing of future events, and retrocognition, the psychic knowing of past events.
For some strange reason, professional astrologers often claim to be clairvoyant, though there is no essential connection between the one and the other. At the beginning of every new year, clairvoyants make predictions based upon their alleged supernatural power of perception which allows them to see the future. Of the thousands of predictions made, some will come true or be considered close enough for government work to qualify as true. The fact is that even a person with no clairvoyance can predict the future accurately some of the time. Try it. Write up a list of predictions dealing with the economy, fashion, celebrities, natural disasters, scientific discoveries, politics, international events and sports. Make at least twenty predictions, ranging from very vague and safe ones (e.g., there will be an earthquake in California) to very specific ones (e.g., George Bush will have a cancerous tumor removed from his colon). You will probably discover two things a year later when you check your predictions to see how accurate you were. One, you probably find that the more vague your predictions were the more accurate they seem. Two, you will probably find that you were right on the money (or close enough for your money) with one or more of your predictions. How did you do it?
Some predictions come true not because of psychic powers which allow a person to look into the future but because of natural powers which help a person anticipate and predict the future based upon past experience and current knowledge. If I wake up in the morning before my wife wakes up and she calls to me as I am about to leave the bedroom and I say to her "I know, put your clothes in the dryer" before she has a chance to speak, and she says to me "How did you know?" am I clairvoyant? Or am I using past experience and knowledge to anticipate what's on her mind? If I buy stock in Intel and a year later the stock doubles in value, am I psychic? Or did I use experience, knowledge, advice and also get a little lucky?
A friend of mine scoffs at scientific studies about the carcinogenic effects of passive smoke, but he believes Nostradamus predicted Hitler's rise to power. Do you think that being a smoker has anything to do with his rejection of the smoking study? Or do you think he has evidence that the scientists who did the smoking studies, or scientists in general, are biased or frauds or otherwise wrong or untrustworthy? Do you think he has evidence that Nostradamus was a clairvoyant? Or does he have psychic powers which allow him to know that the scientists who say smoking is harmful are wrong but the followers of Notradamus are right?
One of the more common appeals as proof of clairvoyance is the dream come true. You dream of your father's death or you just feel that something bad has happened to your father and soon afterwards you find that your father has in fact died. You can't help but feel that there is some sort of connection between your dream or feelings and the event. (Unless you believe in certain kinds of witchcraft, you don't believe that there is a causal connection, such that your thoughts caused your father's death.) A student of mine who related this account was convinced that she had foreknowledge of her father's death, i.e., she was clairvoyant and had seen into the future. Perhaps; but it seems more likely to me that her anxiety about her father was probably based on the way he lived and her feelings about him. He'd been a hippie in the sixties, living in the Haight Ashbury district of San Francisco. He had been a heavy drug user, especially of psychedelic drugs, and had impregnated a woman who believed in free love and had had sex with several men but somehow tagged this guy as the father. He did not have a strong bond with his daughter and his lifestyle, though no longer that of a hippie, was not conventional and the abuse done to his body and mind during his acid days had taken their toll. My own feeling is that her anticipation of her father's death was probably based on either her experience and knowledge about her father's health, and/or her deep feelings of resentment towards him for not loving her and caring for her as a father should. A dream detail involving her hand on his doorknob [Freudians, please restrain yourseves!] seemed very significant to her. She described how she had gone to see her father and how she had had a premonition of his death when she put her hand on his doorknob. She also recollected doing the same thing in a dream. When she found her father's body, she was convinced the dream had been a precognition. To me, it seemed more likely a case of filling in a memory after the event or of confusing a real experience in the past (of opening a door, her father's or others like his) with a dream event. It is also possible that her dream and her father's death were purely coincidental. It seems likely to me that the content of her dream was based on her knowledge, experience and feelings. The coincidence was that her father died shortly after her dream. It would not surprise me to find that she had had other, similar, dreams about her father and her mother as well, who was not indifferent toward her (as her father was) but was hostile and belittling.
Many believers in clairvoyance base their beliefs on coincidences. You dream of an airplane crash or of a building collapsing or of your house on fire and soon afterwards an airplane crashes (and you might even know or know of someone who died in the crash), you see a newscast which features a story on the demolition of a building (which uncannily looks just like the building in your dream), or your house catches on fire. You will not only not forget such a dream but you may well think you're psychic because of the closeness of detail between your dream and the event. Consider a few things, however. How many of us take the time to write down the details of our dreams when we wake up? Most of us can't remember the details; we're lucky if we can even remember the general thrust of our dreams. Yet, when a precognitive dream occurs it is always remembered with precision down to the last detail. This may be because these are special dreams which impress themselves on us with greater force. But I think it is more likely that the details are supplied by us after the fact. We didn't really dream them; we dreamt them up, maybe not intentionally, but we filled in the details of our dream after we heard of the event the dream supposedly foretold. This filling in the past with the present happens often enough in everyday memories, so why shouldn't it happen with dream memories? In fact, it would seem that there would be a much better chance of accuracy of a memory based on an actual experience than one occurring in a dream. The dream state is not one where our awareness is as acute as the waking state. That is not to say that there are not very vivid dreams that are very difficult, if not impossible, to tell from actual experiences. There certainly are. I think that often many people who think they've done or said or heard something but have no corroborating evidence, have dreamed they did, said or heard things which never actually happened. But their dreams are so vivid that they remember them as if they were actual events. Still, most of the time for most of the people the waking state is a more aware state than the sleeping state and we are more likely to remember, and remember accurately, actual experiences rather than dream ones.
But what about those people who have a premonition about getting on a plane? They don't get on and the plane crashes. Isn't that proof that there is psychic power? I don't see why that would be proof any more than the following story is disproof. A man refuses to get on a plane that was about to take him and his lady friend to Hawaii for a week of fun in the sun. He had bad vibes about the plane. His lady friend flies safely to Hawaii, has a wonderful time, and flies safely back to San Francisco a week later. How many people have not gotten on a plane because they had a premonition of disaster, but have failed to report this because there was no disaster? I guarantee you that how ever many there are every day, we will not read about them in the newspapers or see interviews with the failed clairvoyants on the evening news.
Having a premonition that doesn't pan out does not prove that clairvoyance is impossible. But finding cases of people who have premonitions that do pan out doesn't prove there is clairvoyance. Anecdotes are not evidence. What is needed is a controlled test of clairvoyant powers to rule out the possibility of coincidence. When such tests are done on people who claim they are clairvoyant, they always fail. Why? It is possible that they always fail because testing is bad here, on par with testing religious faith. But it seems more likely that clairvoyants fail controlled tests of their powers because they don't have any special powers. Two things which James Randi has found when he has tested the alleged supernatural powers of psychics is (1) they had never tested their powers under controlled conditions, and (2) those who don't offer preposterous rationalizations for their inability to perform seem genuinely baffled at their failure. Clairvoyants are often not frauds; they genuinely believe in their powers. But they've never tested their powers in any meaningful way.
further reading
-----The Wreck of the Titanic Foretold? edited by Martin Gardner. (Buffalo, N.Y. Prometheus Books, 1986).
Gardner, Martin. How Not To Test a Psychic: Ten Years of Remarkable Experiments With Renowned Clairvoyant Pavel Stepanek (Buffalo, N.Y.: Prometheus Books, 1989).
Glymour, Clark and Douglas Stalker. "Winning Through Pseudoscience," in Philosophy of Science and the Occult, edited by Patrick Grim. 2nd ed. (Albany: State University of New York Press, 1990), pp. 75-86.
Randi, James. Flim-Flam! (Buffalo, New York: Prometheus Books,1982), especially chapter 13 "Put Up or Shut Up" where he gives accounts of tests done on several psychics who have tried to collect the $10,000 Randi has offered to anyone who can demonstrate any psychic power So far, no one has collected.
Randi, James. The Mask of Nostradamus (New York: Scribner, 1990).
Sagan, Carl. Broca's Brain (New York: Random House, 1979), pp. 51-52.