How to Win Every Argument: The Use and Abuse of Logic (2006)

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76 How to Win Every Argument

tends to be more common, and more deceptive, when it appears
in the 'some are not' form.


Since we know that some Marxists are not school-teachers, it follows that
some school-teachers are not Marxists.
(No it doesn't.)

Your own wilful use of this fallacy requires careful planning. It
is a short-range tactical fallacy, and is best concealed by not
letting the audience know if you are talking about 'some' or 'all'.
The claim that 'Texas rabbits are animals which grow to more
than a metre long' is skilfully ambiguous. It is not clear whether it
refers to some Texas rabbits or all of them. Your surreptitious
false conversion would then leave your audience convinced that
any animal in Texas more than a metre in length must be a
rabbit. It would also leave any Texans hopping mad.


False precision

False precision is incurred when exact numbers are used for
inexact notions. When straightforward statements about
experience are decked out in numbers well beyond the accuracy
of possible measurement, the precision is false and can mislead
an audience into supposing that the information is more detailed
than is really the case.

People say the Scots are mean, but they have been shown in surveys to
be 63 per cent more generous than the Welsh.
(What measurement of generosity allows for that kind of a figure to
be put on it?)
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