Turtles Upon Turtles: Turtles All the Way Down

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“A well-known scientist once gave a public lecture on astronomy. He described how the earth orbits around the sun and how the sun, in turn, orbits around the center of a vast collection of stars called our galaxy. At the end of the lecture, a little old lady at the back of the room got up and said: 

“What you have told us is rubbish. The world is really a flat plate supported on the back of a giant turtle.” 

The scientist gave a superior smile before replying, “What is the turtle standing on?”

“You’re very clever, young man, very clever,” said the old lady. “But it’s turtles all the way down!”

— cited in Stephen Hawking’s, A Brief History of Time, 1988

“Turtles all the way down” is a jocular expression of theInfinite Regress problem in cosmology posed by the “Unmoved Mover” paradox. A comparable metaphor describing the cause and consequence problem as a cycle is the “Chicken and Egg” problem. In epistemology the problem is known as the Münchhausen Trilemma.”