Neurath's boat (or Neurath's ship) is a simile used in anti-foundational accounts of knowledge, especially in the philosophy of science. It was first formulated by Otto Neurath. It is based in part on the Ship of Theseus which, however, is standardly used to illustrate other philosophical questions, to do with problems of identity.[1] It was popularised by Willard Van Orman Quine in Word and Object (1960).
Neurath used the simile in several occasions,[1][2] the first being in Neurath's text "Problems in War Economics" (1913). In "Anti-Spengler" (1921) Neurath wrote:
We are like sailors who on the open sea must reconstruct their ship but are never able to start afresh from the bottom. Where a beam is taken away a new one must at once be put there, and for this the rest of the ship is used as support. In this way, by using the old beams and driftwood the ship can be shaped entirely anew, but only by gradual reconstruction.[2]
Neurath's non-foundational analogy of reconstructing piecemeal a ship at sea contrasts with Descartes' much earlier foundationalist analogy—in Discourse on the Method (1637) and Meditations on First Philosophy (1641)—of demolishing a building all at once and rebuilding from the ground up.[3] Neurath himself pointed out this contrast.[2][4]
The boat was replaced by a raft in discussions by some philosophers, such as Paul Lorenzen in 1968,[5] Susan Haack in 1974,[6] and Ernest Sosa in 1980.[7] Lorenzen's use of the simile of the raft was a kind of foundationalist modification of Neurath's original, disagreeing with Neurath by asserting that it is possible to jump into the water and to build a new raft while swimming, i.e., to "start from scratch" to build a new system of knowledge.[5][8]
Prior to Neurath's simile, Charles Sanders Peirce had used with similar purpose the metaphor of walking on a bog: one only takes another step when the ground beneath one's feet begins to give way.[9]
If we envision natural language as a ship at sea, then our situation can be described as follows: If we are unable to make landfall, then our ship must have been constructed on the high seas—not by us but by our ancestors. Our ancestors must have been able to swim and have somehow carpentered together a raft out of, say, driftwood. They then continually improved on this raft until today the raft has become a comfortable ship. So comfortable that we no longer have the courage to jump into the water and once more start from scratch. To solve the problem of the method for thought, we must put ourselves in such a shipless condition, that is, bereft of language, and then attempt to retrace the activities whereby we could, while swimming free in the middle of the sea of life, build for ourselves a raft or even a ship.
Certainly some logic is taken for granted in the presentation of the pragmatist picture. But to suppose that this shows that picture to be incoherent is to forget, what is crucial, that we are, to use Neurath's figure, rebuilding our raft while afloat on it.
The coherentists reject the metaphor of the pyramid in favor of one that they owe to the positivist Neurath, according to whom our body of knowledge is a raft that floats free of any anchor or tie. Repairs must be made afloat, and though no part is untouchable, we must stand on some in order to replace or repair others. Not every part can go at once.
Peirce's view is similar to Neurath's. Inquiry is the process of acquiring beliefs by making adjustments to our body of background belief. We revise our beliefs (and add or subtract beliefs) so as to better account for and deal with experience. ... Peirce uses a metaphor similar in spirit to Neurath's boat. Inquiry 'is not standing upon the bedrock of fact. It is walking upon a bog, and can only say, this ground seems to hold for the present. Here I will stay till it begins to give way.' (CP 5.589)