If friends tells us they’ve just seen the baby elephant in the zoo, or they’ve just been to Paris, of course we believe them. But if they tell us that the baby elephant was striped, or they have been impregnated by aliens, or have just seen Elvis levitating in the park, then it is time to put our critical thinking caps on.

Strange things may turn out to be true, but we require proof - evidence which can be checked, before drawing conclusions.

It is hoped that a clearer understanding of critical thinking and the scientific approach will unfold as we progress through the book. Almost all of us know how to think and have common sense. We do not believe that the moon is made of green cheese even though very few of us have been there.

But do we use critical thinking as often as we should?

What is critical thinking?

It is an over-used term and nearly everyone is in favour of it. In this document we mean an ability to think for ourselves, by examining the evidence and arguments, using a scientific approach and not accepting on trust the views of the group, or the anecdotal evidence (i.e. stories) of others. Gullibility and an inability to think critically are at the root of many of the confusions and dilemmas which face us today.


"Nullus in Verba"

(take no-one’s word for it)

Motto of the Royal Society, Britain’s oldest scientific society
The aims of the document are:
Some paranormal beliefs may be harmless enough, and might even be helpful to some, for example to those who feel themselves to be in touch with departed loved ones. However, they may also give false hope to vulnerable people, and deprive them of their hard earned money at the same time. (Psychics and fortune tellers are not always cheap.) Such beliefs might also lead to more dangerous ideas - from phoney cancer cures to religious cults which, in extreme cases could cost you your worldly possessions, your sanity, or even your life (see chapter on cults). The belief that people can be born or turned into witches with special powers, or that children can be possessed by devils, could lead to bullying at school, child abuse and occasionally death.

It is important for us to be able to inform ourselves and examine arguments critically. The better our understanding, for example, of the difference between objective evidence and anecdotal evidence, or between science and pseudo-science, and the better our understanding of how our beliefs are formed, the less likely we are to be conned by people offering expensive miracle cures, by adverts for beauty products, by cults and their charismatic leaders, by people claiming to have been abducted by aliens and so on. (Terms such as pseudo-science will be explained as we go. See also Glossary)

Perhaps Voltaire was not going too far when he suggested that we, the human race, will only stop doing daft things when we stop believing daft things.

Most of us are in urgent need of a spell in a scientific purgatory.



  • to investigate some of the claims of the paranormal - to examine the evidence and to suggest possible natural explanations
  • to try to offer a taste, a glimpse into the wonders, the mysteries and the liberating possibilities of science, in contrast to the allure of the paranormal (Love of mystery is a natural and essential aspect of the human mind; the purpose is not to dampen but to encourage it)
  • to encourage an understanding of the difference between science and pseudo-science, and to put us on our guard against intellectual dishonesty