## Russell's Paradox

*A*and its negation

*not A*to both be true. How can this be, and be coherent? What does it all mean?

**Richard Elwes**explores how these questions brought triumph to one man and ruin to another, ventures to the limits of mathematics and finds that, with infinity, you're spoilt for choice.

Suppose you walk past a barber's shop one day, and see a sign that says

"Do you shave yourself? If not, come in and I'll shave you! I shave anyone who does not shave himself, and noone else."

This seems fair enough, and fairly simple, until, a little later, the following question occurs to you - does the barber shave himself?

**Jon Walthoe**explains the tricks involved and how great thinkers like Pythagoras, Newton and GĂ¶del tackled the problems.