Fuzzy Thinking and PseudoScience
This list is abstracted from "Why People Believe Weird Things", written. by Michael Shermer. Reading this book is highly recommended. Particularly, chapter 3 of Shermer is recommended here. It provides an excellent outline of fallacies in thinking.
1. Anecdotal evidence is not useful.
All an anecdote tells you is what happened in one case. It tells
you nothing about the general population and you cannot draw any
general conclusions from it. You must have well-designed and controlled
experiments to get enough data to reach real conclusions.
2. You need more than scientific language.
Words and phrases must have precise operational definitions. All
hypotheses must be testable.
3. Bold claims need evidence.
Extravagant claims require a lot of evidence. The boldness of a claim
does not make it true. A far-out claim will not be accepted until it has
been successfully tested many times. The bulk of evidence must support it.
4. Radical (heretical) claims can be wrong.
Surely the Wright brothers got laughs concerning their attempt to fly.
Alfred Wegener was scorned when he proposed that Earth's continents
actually move around. These ideas survive because they stood the test.
The Wright brothers' airplane actually flew, and a mass of evidence has
shown that Wegener was right. But - there is a large number of other
radical claims that did not withstand the tests and have been forgotten.
5. Where is the burden of proof?
Who must prove what? The person making an extravagant claim must prove,
via experiments and evidence, that the new claim is actually more valid
than current ideas. The new hypotheses must make better predictions and
successfully explain more phenomena better than current theory. The
current experts are not obligated to prove that their idea is better.
6. Rumors are not necessarily real.
You have almost certainly heard some wonderful story and later wondered
if could really be true. Large numbers of such stories fall into the
category of "urban legends," meaning that they never really happened.
It is wise to take these stories as amusing fiction until you can find
some confirmation of them.
7. Unexplained does NOT mean not explainable.
The fact that you have never seen or cannot explain some phenomenon
does NOT mean that it must be some unexplained supernatural thing.
It would be quite arrogant to assume that you know everything.
8. Watch for rationalization of failures.
Pseudoscience cannot tolerate failures; they will be rationalized or
explained away in some manner. True science must accept negative
results as part of the search for the truth.
9. Look out for "post hoc, ergo propter hoc" reasoning.
If event B follows event A, that does NOT prove that A caused B.
Event B could follow A purely by chance. You must have well-designed
and controlled experiments to show that B always follows A. A single
occurrence is not sufficient.
10. Beware of coincidence.
Truly random behavior can produce some interesting coincidences. Causal
relationships do not always exist. Some interesting combination of
events may be nothing more than chance. The fact that you have never
heard of it before may mean simply that the probability of it is very
low and you don't expect to see it often.
11. Check the misses as well as the hits.
Is the thing you are looking at really representative of its population?
If one prediction of a "psychic" appears to be correct, how many others
were not correct? We tend to remember the hits and forget the misses.
None of this is intended to say that there are no problems in real scientific thinking.
1. Theory influences observations.
What you see is often influenced by what you expect to see. Observations
will be interpreted according to current knowledge, which can obscure
important implications of the observations.
2. Observations change the observed quantity.
The classic example of this is found in the measurement of the motion
or position of a sub-atomic particle. The process of measuring perturbs
the particle.
3. Instrumentation influences results.
The basic idea here is this: that which your instruments cannot detect
might not exist. It might be below your detection limit.
There are historical examples of this.
Spectacular advances in knowledge often occur when
detection capabilities improve so that previously unseen things or phenomena
can be observed.