Use argument by analogy to help support a case but do not
rely upon it. Don’t allow anyone else to get away with far-
fetched analogies. They should be tested and their relevance
should be proved.
Using words ambiguously
The Lewis Carroll approach – ‘When I use a word it means just
what I choose it to mean, neither more nor less’ – is a favourite
trick of those who aim to deceive. People use words that beg the
question; that is, they define a word in a special way that
supports their argument. They shift the meaning of words in
different contexts. They may choose words which have the same
meaning as each other but which show approval or disapproval.
There is a well-known saying that the word ‘firm’ can be
declined as follows: ‘I am firm, You are obstinate, He is
pigheaded.’
Chop logic
‘Contrariwise,’ continued Tweedledee, ‘if it was so, it might be, and if
it were so, it would be; but as it isn’t, it ain’t. That’s logic’.Chop logic is not quite as bad as that, but it can be equally
misleading. It includes such debating tricks as:
■ selecting instances favourable to a contention while ignoring
those that conflict with it;
■ twisting an argument advanced by opponents to mean
something quite different from what was intended – putting
words in someone’s mouth;
■ diverting opponents by throwing on them the burden of
proving something they have not maintained;
■ deliberately ignoring the point in dispute;
■ introducing irrelevant matter into the argument;
■ reiterating what has been denied and ignoring what has been
asserted.
How to Think Clearly 301