Turtles Upon Turtles: Turtles All the Way Down
“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 the Infinite 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.”"