"Russel's Papadox" joke

The great logician Betrand Russell (or was it A.N. Whitehead?)
once claimed that he could prove anything if given that 1+1=1.
So one day, some smarty-pants asked him, "Ok. Prove that
you're the Pope."
He thought for a while and proclaimed, "I am one. The Pope
is one. Therefore, the Pope and I are one."
- Donald