How to convince a machine that two plus two equals five

(Disclaimer: the alternative to these facts is unbearable.)

They say that humans are smarter than machines, but that a machine can never -- at least for some particular meanings of never -- go wrong, while a human could easily be stupid enough to believe that two plus two equals five -- at least for some particular meanings of two, plus and five.

But that is obviously a gross misunderstanding. One can as easily convince a machine that two plus two equals five, as follows. Define a function called "my plus", which takes as arguments two items a and b, whose implementation is the following. If a is two and b is two, then equals five; else equals whatever the machine implicitly understands a plus b means in the machine's narrow view of the world. See? easy.

But then, how to convince a human that two plus two equals five? In precisely the same way.

Machines, ever the perfect slaves.