Precognition

Precognition refers to a type of extra-sensory perception which would (if it exists) allow a person to perceive future events. In the New Age world as well as the world of con artists, such "gifts" are possessed by only the select, special few, and are therefore, likely to be pricey to see "in action".

Precognition is similar to clairvoyance, and makes a great narrative device because it brings up ideas of fate, destiny, and free will &mdash; so people can be easily attracted to the idea. In the real world, it is, of course, bullshit pseudoscience.

Unless it's not, …

Explanations of anecdotal evidence
Most "evidence" for precognition tends to come from anecdotes rather than any actual data &mdash; indeed, properly controlled trials show no effect. People who don't do this for a living &mdash; such as dear ol' Aunt Gladis who says she can predict the future &mdash; tend to rely on confirmation bias and selective reporting, which are both effects of the human mind recalling and confirming some instances and forgetting and disconfirming others.

That is to say, dear Aunt Gladis had a dream one night that a plane would crash and the next day one did. So she says to herself "I can predict the future". And if it should happen again, for instance she dreams her son would get sick and he does, that reinforces her belief that she is "seeing the future." However, what she conveniently forgets are the thousands of other dreams that "predicted" the future, which never played out in the real world. This is because cases that don't agree aren't particularly interesting or notable &mdash; no one remarks at a lack of co-incidence. Furthermore, the worldwide frequency of plane crashes is about once every 2 or 3 days, so there's an excellent chance that there will be a plane crash within 1 day of dreaming about one.

So should Aunt Gladis be thinking of a dear old friend and then a minute later they happen to call her, she'll remark upon it, but if the friend calls her out of the blue when she wasn't thinking of them, she'll not mention the lack of a premonition. The confirmation bias effect is pretty much responsible for all reports of psychic powers, from mediumship to remote viewing. Remarkably, even apparently scientific tests can fall foul of these effects. When someone is asked to exhibit some form of telepathic power and they get it wrong, the statistical context is often brought up in a certain way to say that this sort of incorrect guessing is inevitable due to chance, or that not everyone is psychic. On the other hand, if they happen to guess correctly, the statistical context focuses on the odds that the individual has defied in order to make their prediction. For example, someone correctly guessing several Zener cards in a row has defied 100 to 1 odds for correct guessing, and this is hyped even though it is a plain statistical possibility.

Mythological precognition
Most mythologies throughout the world address precognition in some way. Someone, usually a Hero archetype, or someone from the 'divine' realm will warn the world about some impending disaster they foresaw in a dream, or that they were warned about by some kind of mysterious otherworldly voice. Mythical figures have the added advantage of generally focusing their precognition on things that are so far in the future, no one alive can call their bluff. The Christian Bible calls it prophecy if it's from the acceptable God, and "divination" if it's from a big bad ugly god. Not surprisingly, divination is a sin, but prophecy is the work of "Holy Men". If the prophecy comes true, the old fart is hailed as a man of God. If the prophecy does not come true, it is put down as something which has a future fulfillment after the rapture.

Jesus predicted that Peter would deny him three times, and that Judas would betray him. Those two, at least if you follow the redacted version of the scene, came true.

Folk beliefs
In Finland, there is a tradition of etiäinen, which is a ghost-like doppelgänger that precedes the arrival of a real person, or more generally, any premonition. In Norway, the same entity is called vardøger. An etiäinen is usually heard, rarely seen. Etiäinens can for example make noise in the hallway in the same manner the real person will when he arrives. Like ghosts, etiäinens are spontaneous and can cause anxiety. Unlike a ghost, which is usually associated with a particular location, an etiäinen can occur anywhere. Besides the mundane event of arrival, a recently deceased person can appear as an etiäinen.

More generally, the Finnish word etiäinen also refers to premonition. Even just a vague feeling that something particular will happen in the future can be called etiäinen, if it appears suddenly and spontaneously. This is similar to déjà vu, except that the event is in the future instead of currently occurring, i.e. an experience of "remembering the future". The experience can be vivid and very convincing. Etiäinen is still a living tradition; you can have an "etiäinen" about a SMS message for example.

This is all in line with the fact that awake auditory hallucinations and mild delusions are not particularly rare. While they are common in mentally ill people, they still occur in persons identified as sane. Transient auditory hallucinations featuring recently deceased family members occur in the majority of the population. Research of these phenomena is nevertheless difficult, because they are only individual experiences, which cannot be quantified or experimentally proven.

Etiäinens aren't really something you could commercialize, because they can't be made to appear on demand. Nevertheless, when clairvoyants are introduced, the ability to see etiäinens is treated as evidence of "psychic powers". These claims are typically unproven or unprovable.

Hitler was psychic
British historian Holocaust denier David Irving believes The Führer himself foresaw that little David would turn up and specially chose David to write about him. Despite Hitler having such wonderful psychic powers, he overlooked the catastrophic defeat that followed from invading Poland and starting World War II? Well, it must be pleasant to think that you are specially chosen by God the Führer and little David might not want to spoil things by thinking it through.

Princess Diana
Medium and general psychic Sally Morgan foresaw the road accident that killed Princess Diana a year before it happened but didn't warn the princess. Sally's powers weren't quite working, and so she thought the victim was the queen, though she didn't get round to warning the queen either.

Science and precognition
But wait! If precognition is possible, then it must have been studied, and there must be something to it, right? Of course, right &mdash; if by precognition, you mean a fraction of a second before you are conscious of your choice, a computer using live fMRI can "see" your choice being made, and predict it before you make that choice. Given that this prediction is made a fraction of a second before the predicted event, its utility is limited.