The Philosophers' Magazine

Issue 44, 1st quarter 2009

Best kept Secrets

Brendan Larvor
Pages 83-88

Three is a magic number

Logical theory – and philosophical theory generally – is just that, theory. Generations of logic students felt a sort of unease about it without knowing what to do about it. Nowadays, students of mathematical logic feel a similar unease when faced with the fact that in standard predicate calculus, “All unicorns are sneaky” is true precisely because there are no unicorns. Blanché’s analysis reminds us that such feelings of unease may indicate a shortcoming in the theory rather than in the student’s understanding.