■ reaching false conclusions;
■ begging the question;
■ false analogy;
■ using words ambiguously;
■ chop logic.
These are discussed briefly below.
Sweeping statements
In our desire for certainty and to carry the point we often indulge
in sweeping statements. We sometimes then repeat them more
and more loudly and angrily in order to convince our opponent.
If we do it often enough and forcibly enough we can even
deceive ourselves.
It has been said that ‘it’s never fair, it’s never wise, it’s never
safe to generalize’. But that is a generalization in itself. Scientific
method is based on generalizations. They can be valid if they are
inferred properly from adequate, relevant and reliable evidence.
Generalizations are invalid when they have been produced by
over-simplifying the facts or by selecting instances favourable to
a contention while ignoring those that conflict with it. The classic
form of a fallacious generalization is the contention that if some
A is B then all A must be B. What frequently happens is that
people say A is B when all they know is that someA is B or, at
most, A tendsto be B. The argument is misleading unless the
word ‘some’ or ‘tends’ is admitted.
Many of the fallacies considered below are special cases of
unsafe generalization, the most common symptom of unsound
reasoning.
Potted thinking
Potted thinking happens when we argue using slogans and
catch phrases, when we extend an assertion in an unwarrantable
fashion.
It is natural to form confident beliefs about complicated
matters when we are proposing or taking action. And it is
equally natural to compress these beliefs into a single phrase or
thought. But it is dangerous to accept compressed statements
that save us the trouble of thinking. They are only acceptable if
fresh thinking has preceded them.
296 How to be an Even Better Manager