A Special Case

A biologist, a statistician, a mathematician and a computer engineer are
on a photo-safari in Africa. They drive out into the savannah in their
jeep, stop and scour the horizon with their binoculars.
The biologist: “Look! There’s a herd of zebras! And there, in the middle:
a white zebra! It’s fantastic! There are white zebras! We’ll be famous!”
The statistician:
“It’s not significant. We only know there’s one white zebra”
The mathematician:
“Actually, we know there exists a zebra which is white on one side”
The computer engineer:
“Oh no! A special case!”