Testimony

For much of what we believe, we have to rely on what other people tell us. Their reports are as liable to error as our
own. Still, we can be reasonably certain of some people’s reports and reasonably doubtful of others. In chapter
three, we’ll present some rules for deciding which reports are trustworthy. Here we will simply raise a few
cautionary concerns about relying on testimonials.
Testimonials are often very vivid and detailed, making them appear very believable. They are often made by
enthusiastic people who seem trustworthy and honest and who lack any reason to deceive us. They are often
made by people with some semblance of authority, such as those who hold a Ph.D. in psychology or physics.
To some extent, testimonials are believable because people want to believe them [See wishful thinking,
below.]. Often, one anticipates with hope some new treatment or instruction. One’s testimonial is given soon
after the experience while one’s mood is still elevated from the desire for a positive outcome. The experience
and the testimonial it elicits are given more significance than they deserve. (Carroll 2003: 375).
Because it is easy for people to deceive themselves (see self-deception, below), scientists do not usually rely on
testimonials or anecdotes, except perhaps to stimulate them to design controlled experiments to test hypotheses.
(Designing controlled experiments is discussed below in the chapter on causal reasoning.)
The testimonial of personal experience in paranormal or supernatural matters has no scientific value. If others
cannot experience the same thing under the same conditions, then there will be no way to verify the
experience. If there is no way to test the claims made, then there will be no way to tell if the experience was a
delusion or was interpreted correctly. If others can experience the same thing, then it is possible to make a test
of the testimonial and determine whether the claim based on it is worthy of belief.
Testimonials regarding paranormal experiences are scientifically worthless because selective thinking and selfdeception
must be controlled for. Most psychics do not even realize that they need to do a controlled test of
their powers to rule out the possibility that they are deceiving themselves. They are satisfied with their
experience as psychics. Controlled tests of psychics will prove once and for all that they are not being selective
in their evidence gathering, that is, that they are counting only the apparent successes and conveniently
ignoring or underplaying the misses. Controlled tests can also determine whether other factors, such as
cheating might be involved. (Carroll 2003: 375).
Thus, while testimonial evidence is sometimes essential—as in telling your physician your symptoms—it is easy to
overvalue other people’s experiences, especially if they are put forth enthusiastically and authoritatively.