Quite possibly the greatest book ever written on the subject of turtle stacking.
-- Lisa Simpson on Yertle the Turtle by Dr. Seuss
A well-known scientist -- Bertrand Russell, in one version of the story -- was giving a public lecture on astronomy. He described how the earth orbits around the sun, which, in turn, orbits around the center of the Milky Way, one of billions of galaxies. At the end of the lecture, an old lady at the back of the room stood up and said, "You're completely wrong, young man. The Earth is flat and is supported on the back of a giant turtle." The astronomer was taken aback, but stepping gamely up to the plate, responded, "I understand, Madam, but can you tell me what the turtle is standing on?" "Another turtle, of course." Taking a deep breath, he started to say, "Well yes, but ..."
"It's no good, Sonny," she interrupted. "It's turtles all the way down!"
The "Turtle Problem" is routinely used as a shorthand phrase for the philosophical notion of "infinite regression." The idea is that a solution which depends on a never-ending series of similar steps is no solution at all. Take, for instance, the policing problem. To keep the police honest, you need someone to police them, the police-police. But to keep them honest, you need the police-police-police ... ad infinitum.
Then there's the so-called Intelligent Design approach to creation, which claims that a complicated world couldn't have happened on its own, that it needed a designer, usually referred to as "God." Since God must be at least as complicated as her/his creation, then God also has a creator, God's God. Who in turn would have been created by ... and we're back with the Turtle Problem.
Most meditators, myself included, are quite familiar with the Turtle Problem. I'll be sitting there thinking, "Okay, here I am, staring at a wall." Then comes, "Who is having this thought?" (a standard technique in some forms of meditation), followed instantly by, "Who is having the thought, 'Who is having this thought?'" And before you can say infinite regression, my mind's off and running down mirrored corridors, bouncing the question (as I imagine) between the twin hemispheres of my brain: turtles all the way down.
At which point, any hope that I can ever know for sure What Is Real seems absurd, and the "brains in vats" premise of The Matrix doesn't look quite so weird after all.
Barry Evans (firstname.lastname@example.org) thanks the Agents for letting him believe that he lives and loves in Old Town Eureka.