Exclusive premises 65fallacy quickly to get rid of them so that we can continue as
before.
The exception that proves the rule is a fallacy beloved of those
who are emphatic in their judgements. They have the world
neatly divided into categories, and do not intend the irritant sand
of exceptions to intrude into the well-oiled machinery of their
worldview. In their smooth-running world, all pop stars are drug
addicts, all feminists are lesbians and all young people are
weirdos. Any honourable exceptions to the above categories are
ejected with equal smoothness as 'exceptions that prove the
rule'. The great thing about this particular fallacy is that it renders
your argument invulnerable to factual correction. The most
embarrassing proofs that you are just plain wrong can be swal-
lowed whole as 'exceptions that prove the rule', and need
occasion no more than a slight pause in your declamation.
'Lend us a fiver. I've always paid you back before.'
'What about last week?'
'That was the exception that proves the rule. You know you'll get it back
in the long run. '
(Put on your trainers.)Exclusive premises
The standard three-line argument called a syllogism has two
premises and a conclusion; the premises are the evidence and
the conclusion is deduced from them. If both of the premises are
negative, no conclusion can be validly drawn from them and the
fallacy is called the fallacy of exclusive premises.
No handymen are bakers, and no bakers are fishermen, so no handymen
are fishermen.