William James Tychonievich has an interesting post "The influence of adjacent lines of text" about how when reading, nearby lines of text can cause the reader to misread a particular line. He also has a fascinating idea:
"In this case, the misreading was almost immediately corrected, lingering just barely long enough to register consciously. I wonder how many similar mistakes we make, just below the threshold of consciousness, every time we read, and what subliminal psychological effects they might sometimes have. I wonder if such errors could be anticipated and even consciously designed and exploited — either as a poetic technique or for more sinister purposes."
A similar thing occurs when one misreads a particular word which then affects the meaning of a sentence. The writer Gene Wolfe has said that he was reading a story where there was a line that said something like "the mountains are nice," but he read it as "the mountains are mice." So, he started thinking about what that would mean and he ended up writing a story titled "The Mountains are Mice" where people do experiments in mountains, so the mountains are like lab mice.
Something similar has happened to me on a few occasions. One time several years ago I was looking at classical music CDs and I read a title as "The Dalmation of Faust," though actually it was "The Damnation of Faust." A few weeks ago, I was reading Bruce Charlton's blog and glanced over to the sidebar and read the title of my post "Some thoughts on physics" as "Some thoughts on psychics." As it happens, I do have some thoughts about psychics.
I believe that precognition and clairvoyance can occur and have occurred in the past. The mathematician Kurt Godel also believed in ESP and in particular, he thought that the large number of frauds distracted from the genuine cases. Many people have had precognitive dreams, which become apparent after the fact. William James Tychonievich records an interesting example here. Others have had dreams which warn them of some danger. There have also been examples of people who have seen events from a distance. In 1759, Emanuel Swedenborg (1688 - 1772) saw a fire in Stockholm while he was at a dinner party in Gothenburg and was able to describe features of the fire accurately. Tycho Brahe had a jester named Jep, who was also supposed to be clairvoyant. Here is an interesting quote from an 1890 biography of Brahe by John Louis Emil Dreyer:
"Two other inmates of Tycho’s house may also be mentioned here. One was a maid of the name of Live (or Liuva) Lauridsdatter, who afterwards lived with Tycho’s sister, Sophia, and later was a sort of quack-doctor at Copenhagen, where she also practised astrology, &c. She died unmarried in 1693, when she is said to have reached the ripe age of 124. The other was his fool or jester, a dwarf called Jeppe or Jep, who sat at Tycho’s feet when he was at table, and got a morsel now and then from his hand. He chattered incessantly, and, according to Longomontanus, was supposed to be gifted with second-sight, and his utterances were therefore listened to with some attention. Once Tycho had sent two of his assistants to Copenhagen, and on the day on which they were expected back the dwarf suddenly said during the meal,” See how your people are laving themselves in the sea.” On hearing this, Tycho, who feared that the assistants had been shipwrecked, sent a man to the top of the building to look out for them. The man came back soon after and said that he had seen a boat bottom upwards on the shore, and two men near it, dripping wet. … When any one was ill at Hveen, and the dwarf gave an opinion as to his chance of recovery or death, he always turned out to be right."
So, it seems like some people do have the ability to be clairvoyant or predict things. I am not a believer in determinism, so in this case I would understand predictions to be in the sense of forseeing a consequence of an action that has already been undertaken, though the actual way it may play out is not set in stone. In addition, if the action is arrested, the future may change.
Nonetheless, the problem seems to come when people say "I am psychic," rather than, "I have had a psychic experience." I think that underlying the physical laws of the universe, there are other principles that are not themselves physical and hence not mechanical. So, they cannot be counted upon to work in the same way every time. Clairvoyance is rare and those who can do it consistently are rare even among clairvoyants. An interesting example of someone who seemed to be able to have insights consistently comes from the chapter "Suspicions of Something More" by Thomas V. Morris from the book God and the Philosophers:
"I married a wonderful young woman with sparkling eyes whom the reportedly psychic grandmother of a high school friend had once described to me many years before as my future wife, although we were not to meet until my junior year at college, and then I set myself to prepare at Yale for the sort of vocation this same remarkable older woman had told me I would follow, despite all my plans for a business career. For someone unfamiliar with modern, logical, analytic philosophy of religion, her description of my future vocation in context was striking - 'something like science, only spiritual,' she had said. During my graduate years, I studied the techniques of science to pursue topics of the spirit."
In this case, I would view the prediction not as looking into the future as if it were a prerecorded video, but as being able to look into Morris's deepest wishes and goals and those of others (perhaps unknown to them) and make predictions from those. Similar to how if one knows someone very well, it is possible to predict their behavior, though not in a mechanical way.
An analogy to psychic experiences can be made with writers. I think writers can also be inspired by something beyond themselves and then they try to translate this into a story. C.S. Lewis said that his stories began with pictures (the inspiration), which he then had to link together with invention. Just as different writers have different amounts and kinds of inspiration, different psychics have different amounts and kinds of insight.
But, because it is not mechanical, when those who cannot do it on command try to force prediction or clairvoyant visions, it usually ends in falsity. Also, if people use their gifts for the wrong reason, they will probably go away in that case as well.