Turtles all the way down

"Turtles all the way down" is a humorous expression of the problem of infinite regress. The saying alludes to the mythological idea that the earth rests on the back of a large beast (World Turtle/Tortoise) or beasts (World Elephants). Those beasts, in turn stand on the back of another beast. In one version, it is a giant turtle who swims in an endless ocean. In another version, it is yet another turtle standing on a column of turtles continuing indefinitely (i.e., "turtles all the way down").

Quotes with "turtles all the way down" have been incorrectly attributed to William James and Bertrand Russell (see "Variations" section below). The earliest allusions in print to this mythological story can be found in the 17th and 18th centuries, but the first publication of "turtles all the way down" is attributed to Joseph Berg in 1854 (see below). The quote was further popularised by John Green's book of the same title - in which he used the quote in reference to thought spirals (which both he, and the protagonist of the book, experienced as a symptom of their OCD).

Quotes

• Some ancient Asian cosmological views are close to the idea of an infinite regression of causes, as exemplified in the following apocryphal story: A Western traveler encountering an Oriental philosopher asks him to describe the nature of the world: “It is a great ball resting on the flat back of the world turtle.” “Ah yes, but what does the world turtle stand on?” “On the back of a still larger turtle.” “Yes, but what does he stand on?” “A very perceptive question. But it’s no use, mister; it’s turtles all the way down.”
  • Carl Sagan, Gott and the Turtles (1974), essay published in Broca's Brain: Reflections on the Romance of Science (1979)

• My opponent's reasoning reminds me of the heathen, who, being asked on what the world stood, replied, "On a tortoise." But on what does the tortoise stand? "On another tortoise." With Mr. Barker, too, there are tortoises all the way down.
  • Joseph Frederick Berg (1854); from a transcript of remarks addressed to his fellow clergyman Joseph Barker.

Variations

• There is an Indian story -- at least I heard it as an Indian story -- about an Englishman who, having been told that the world rested on a platform which rested on the back of an elephant which rested in turn on the back of a turtle, asked (perhaps he was an ethnographer; it is the way they behave), what did the turtle rest on? Another turtle. And that turtle? 'Ah, Sahib, after that it is turtles all the way down.'
  • Clifford Geertz, The Interpretation of Cultures (1973), p. 28-29.

• Like the old woman in the story who described the world as resting on a rock, and then explained that rock to be supported by another rock, and finally when pushed with questions said it was "rocks all the way down," he who believes this to be a radically moral universe must hold the moral order to rest either on an absolute and ultimate should or on a series of shoulds "all the way down."
  • William James, Rationality, Activity and Faith (1882). James referred to the fable of the elephant and tortoise several times, but told the infinite regress story with "rocks all the way down" in this 1882 essay.

• If everything must have a cause, then God must have a cause. If there can be anything without a cause, it may just as well be the world as God, so that there cannot be any validity in that argument. It is exactly of the same nature as the Hindu's view, that the world rested upon an elephant and the elephant rested upon a tortoise; and when they said, 'How about the tortoise?' the Indian said, "Suppose we change the subject."
  • Bertrand Russell, Why I Am Not A Christian (1927).

External links

• Full text of Carl Sagan's Broca's Brain: Reflections on the Romance of Science
• Full text of Berg & Barker's Great Discussion on the Origin, Authority, and Tendency of the Bible
• Full text of Bertrand Russell's Why I'm Not A Christian