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2+2 = 5

Bertrand Russel used humour to show that whatever is logical is not necessary true. He was saying the following

Do you pretend that if 2+2=5, then Bertrand Russel is the pope ?
  1. Suppose that 2+2=5
  2. Let's substract 2 from each side, then 2=3
  3. By symmetry we have 3=2
  4. If you substract 1 on both sides, 2=1
  5. Now the pope and I are two distinct people, since 2=1 the Pope and Russel are one.
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