When I was growing up, I found myself, like all young people, in a world full of
adults telling me stories. Stories about the nature of the world and the place of
humans in it, stories about what to believe and how to behave. My problem was that
there were many different stories, so how do you decide to choose between them
and form your own views? I asked my father about this, and he advised me, when
forming my view of the world, not to take any notice of the status of people making
particular claims. It did not matter, he said, whether they were called prince or
bishop or professor, or whether they wore fancy clothes like mitres or mortar boards.
The only thing that mattered, he said, was the quality of the evidence in support of
the claims they were making, and that I should be the judge of that quality. By quality,
he meant how robust was the evidence?Was it just an opinion derived from what
other people said, or was it based solidly on empirical observations anyone could
make? In other words, how scientific was the evidence?
This book is based on my father’s advice to seek out the best-quality, empirical
evidence you can find, and stick to what it implies until better evidence comes along.
It is the quality of the evidence that you need to learn how to evaluate. In this book
I discuss the criteria you should bear in mind when evaluating the evidence for any
claim, in the hope that this will help you to develop an independent, critical way
of thinking. Reduced to the simplest terms, my advice to you when confronted by
people making claims about any subject is not to accept their claims at face value,
but to ask “How do you know that?” and rigorously examine the quality of the
replies they give.