A further danger in drawing conclusions from evidence is to
forget that circumstances may alter cases. What has happened in
the past will not necessarily happen again unless the circum-
stances are the same. You may be able to infer something from
history but you cannot rely on that inference. Times change.
Begging the question
We beg the question when we take for granted what has yet to be
proved. This can take the form of assuming the point in dispute
without adequate reason; what the logicians call petitio principii.
If you spot anyone taking for granted a premise which is not
contained in the conclusion you must challenge the assumption
and ask for information about the premises upon which the
conclusion is based. You can then assess whether or not the
conclusion follows logically from those premises.
Challenging assumptions is a necessary part of thinking
clearly. You should challenge your own assumptions as well as
those made by others.
False analogy
Analogy forms the basis of much of our thinking. We notice that
two cases resemble each other in certain respects and then infer
an extension of the resemblance. Analogies also aid under-
standing of an unfamiliar topic.
Analogies can be used falsely as vivid arguments without any
real evidence. Just because A is B, where both are familiar
matters of fact, does not mean that X is Y, where X and Y are
unfamiliar or abstract. When we argue by analogy we claim that
if:
x has properties of p1, p2, p3 and f, and
y has properties of p1, p2 and p3, therefore
y also has the property of f.This could be true unless y has a property incompatible with f, in
which case the argument is unsound.
Analogies may be used to suggest a conclusion but they
cannot establish it. They can be carried too far. Sometimes their
relevance is more apparent than real.
300 How to be an Even Better Manager