I am not a psychic, but as a professional sceptic I occasionally play one to reveal the tricks used by peddlers of the paranormal.
The most common ruse is known as cold reading, where you reveal facts about someone you have never met. It is not difficult. Armed with the knowledge that certain facts are likely to apply to anyone (e.g. a scar on your knee, a white car in your past, the number two in your address), a friendly and confident patter punctuated with inquisitive looks and knowing nods - and no moral scruples - you too can be a psychic, astrologer, palm reader or tarot card diviner. No matter how you market yourself, the process is the same.
And it's easy to find customers, because a great number of people are ready to believe. According to a 2005 Gallup poll, three-quarters of those surveyed believe in at least one paranormal phenomenon, including 41 per cent who are convinced of ESP, 32 per cent of ghosts, 31 per cent of mind reading, 26 per cent of clairvoyance and 25 per cent of astrology.
Spend 10 minutes online and you can catalog many other highly questionable beliefs that aren't related to the paranormal, such as that space aliens landed at Roswell, New Mexico, that the earth was created less than 10,000 years ago, that the Holocaust never occurred, and that 9/11 was orchestrated by the US government to galvanise America for war.
Why do so many people believe such weird things?
First, all humans seek patterns. That's our nature. We are also storytellers because it helps us find meaning in a chaotic world. In order to survive, we have evolved to find cause-and-effect relationships in nature, and then weave a plausible story to explain them. Our ancestors who identified the pattern linking the seasons to animal migrations ate better and left behind more offspring. But because believing that the rain gods can be appeased through rituals isn't fatal, we also have inherited magical thinking. Add to this the fact that many of these beliefs make us feel better, meet some emotional need, promise miracle cures or instant wealth, and in general appeal to our emotional brains and bypass our rational brains.
What can we do about this? Think sceptically. How? Here are a few questions to ask when considering extraordinary claims:
- Is the person making this claim a qualified expert in the field, or a quack? People who are not trained in a subject can make contributions, but it is rare.
- Does the source often make similar claims? Paranormalists and members of fringe groups have a habit of going well beyond the facts.
- Have the claims been verified by another source? Typically pseudoscientists will make statements that are unverified, or verified by a source within their own circle. Who is checking the claim, and who is checking the checkers?
- How does the claim fit with what we know about how the world works? When considered in this manner, get-rich quick schemes and stock-market secrets never sound so good.
- Has anyone gone out of the way to disprove the claim, or have they only sound evidence to confirm it? This is known as confirmation bias, or the tendency to ignore negative evidence. This is why we need the methods of science, which include the attempt to prove yourself wrong.
- Does the preponderance of evidence converge to the claimant's conclusion? The theory of evolution, for example, is proven through a convergence of evidence from a number of independent lines of inquiry. No one fossil proves anything.
- Is the claimant employing accepted rules of reason and tools of research? UFOlogists suffer this fallacy in their continued focus on a handful of unexplained atmospheric anomalies and visual misperceptions while ignoring the fact that the vast majority of sightings are easily explained.
- Has the claimant provided a different explanation for the observed phenomena, or is it strictly a process of denying the existing explanation? This is a classic debate strategy - criticise your opponent and never affirm what you believe in order to avoid criticism. Creationists do this to great effect. But to be legitimate, positive evidence in favor of your idea must also be presented.
- If the claimant has offered a new explanation, does it account for as many phenomena as the old explanation? For example, sceptics who argue that lifestyle, not HIV, causes AIDS do not explain nearly as much of the data as the HIV theory does, such as the rise in AIDS among haemophiliacs shortly after HIV was inadvertently introduced into the blood supply.
- Is there extraordinary evidence for the extraordinary claim? Evidence is key. Normal claims need normal evidence, but extraordinary claims require extraordinary evidence.
Michael Shermer is the publisher of Skeptic magazine, a monthly columnist for Scientific American, and the author of Why Darwin Matters, How We Believe, and Why People Believe Weird Things. He is touring Australia as part of National Science Week 2008.