A mathematician, an engineer and a priest are on an airplane, and the pilot announces the plane is going down, and unfortunately there is only a parachute for him. The pilot jumps out and leaves the three passengers to their own devices.

At first, they are of course shocked and at a loss for solutions to their problems. The engineer decides staying in the plane is suicide, so he does a few quick calculations in his head and jumps out. Mid-air, he manages to adjust his clothes just so into an airfoil of sorts, and slows his descent to the ground enough to survive.

In the meantime, the priest decides to put his faith in God, and also jumps out, all the time praying. Miraculously, he lands in a haystack and survives.

The engineer and the priest, having found each other on the ground, watch the plane on its way down, and see the mathematician jump out as well. He just falls down unceremoniously, and crashes violently into the ground. Horrified, the two rush to where they saw the mathematician hit the ground, approaching with trepidation. As they arrive at the site, they are extremely surprised to find the mathematician dusting off his clothes, completely unharmed. "How on Earth did you survive that?", they ask.

"Induction", replies the mathematician.