Okay so as anyone can tell you, Foucault can be tricky. I might have made some fatal misreadings.
This is my reading of it thus far
(Please take it with a grain of salt):
Summary:
With examples, Foucault is illustrating a long sequence of ideological shifts related to how madness has been interpreted and responded to. He says that there were a series of romantic and satiric "Ships of ____" in literature and art. And claims that among them, the 'Ship of Fools' was the only one to truly exist. Particularly in Nuremberg. He goes on to say that it happened after it was discovered that isolating Lepers in the middle ages actually succeeded in reducing leprosy, and it was then imagined that the same approach could be taken to madness, and then it happened.
He claims that they were handed over to merchants, sailors and pilgrims who would take responsibility for them for a time. It was claimed that the changing scenery, confinement onboard, and religious pilgrimages were thought to have a positive effect on them. At worst the practice was just a way of shuffling the 'mad' around to someone else's backyard.
" But of all these romantic or satiric vessels, the Narrenschiff is the only one that had a real existence—for they did exist, these boats that conveyed their insane cargo from town to town. Madmen then led an easy wandering existence. The towns drove them outside their limits; they were allowed to wander in the open countryside, when not entrusted to a group of merchants and pilgrims. The custom was especially frequent in Germany; in Nuremberg, in the first half of the fifteenth century, the presence of 63 madmen had been registered; 31 were driven away...."
It goes on... Where is he getting these numbers? Maybe it's my monolingual poverty showing but where does he get his sources? Were 'ships of fools' really a thing?
All I can find is references to an allegory in Plato's: Republic, and the poem Foucault mentions. Thanks!
Winifred B. Maher and Brendan Maher in "The ship of fools: Stultifera Navis or ignis fatuus?" (1982, admittedly psychological researchers) allege that various writers have taken Foucault's claim at face value but there is little evidence to support it. This is similarly argued by Andrew Scull's March 2007 article "Foucault's Fictions: Scholarship of Fools) (Times Literary Supplement). And further supported by Richard Wilson ((2013) "Ship of Fools: Foucault and the Shakespeareans"). And Foucault's approach to historical evidence and his accuracy in that work has been criticised before as in Porter's "Great Confinement" (1990). Foucault was more a philosopher than historian, as Gary Gutting argued in his 1994 "Foucault and the History of Madness" (Cambridge Companion to Foucault), Foucault was more interested in broad analysis of historical themes and zeitgeists than specific facts.
So no, it seems unlikely that the ship of fools as a solution to mental illness was ever a thing, or at least that if it was, it was not at all a common or well-documented one.
Though the previous comment have presented a set of articles against Foucault's view in the point of accuracy, there does exist a citation for your questioned part(the Nuremberg and Frankfort regarding Narrenschiff) in the French edition, and, surprisingly, in my country's translation(Korean):
For why this happened, this article tells that the English edition omitted about half the original book and references, by translating the 'pocket edition', which Foucault himself made by editing parts for the public audience(Well, it still never fits the pocket).
Further, the author argues against some scholars who were critical to Foucault regarding hisotrical accuracy; though ones not present and surely older than the scholars cited in the upper comment.
Finally, he guards Foucault by citing a preface to the book-the original French written in 1961 which Foucault has deleted and replaced with a joke in 1972:
To do the history of madness will therefore mean: to make a structural study of the historical ensemble - notions, institutions, juridical and police measures, scientific concepts - which hold captive a madness whose wild state can never in itself be restored; but, short of this inaccessible primitive purity, structural study must ascend back to the decision which at once joins and separates reason and madness; it must strive to discover the perpetual exchange, the obscure common root, the originary affrontment which gives meaning to the unity as much as to the opposition of sense and the senseless.
So basically, Foucault was never trying to write a History of Madness itself; but a history not of 'Madness itself', which is naturally impossible to grasp in the light of reason: thus using the only way possible, by the review of Madness objectified and confined.
I am no expert to him nor history of psychiatry, but it seems there is more to be said than to just say he abridged facts for his structural analysis.
The important thing always to remember when reading Foucault is that for him myths and legends have as much weight as historical events when it comes to tracing the outlines of a discourse. As he is not writing straight history, he does not see a reason to delineate the two. In fact, part of his work is to dissolve the traditional division between the subject and the object. Unfortunately, due to poor translations and the unwillingness to engage with his project, Foucault has suffered from some unfair criticism of his methods.
In his first book Folie et déraison: Histoire de la folie à l'âge classique (translated as Madness and Civilization: A History of Insanity in the Age of Reason), Foucault draws from his training in philosophy and psychology to examine the interplay between text and context and chart the emergence of the discipline of psychiatry and the epistemic shift from “madness” to “mental illness”. Foucault uses the symbol of the “ship of fools” in its various iterations in history, literature, and visual art to explore the pre-modern approach to insanity, which he argues was defined by liberty and itinerancy rather than confinement.
But Foucault is not happy to restrict himself to the realm of the symbolic and cannot resist bringing in real-world examples. Unfortunately, the evidence he cites is not always referenced in a reliable manner. Sometimes, as in the case of the early abridged translations, the references themselves are abandoned. At times, the references are incorrect. For example, in the first chapter of the original French edition of Folie, Foucault refers to the accounts contained in a text by the German historian Theodor Kirchhoff. Unfortunately, the reference in Folie is to Kirchhoff’s Geschichte der Psychiatrie of 1912 when the actual source for the records was his Grundriss einer Geschichte der deutschen Irrenpflege of 1890.
Kirchhoff’s 1890 volume contains numerous examples of the expulsion and transportation of those deemed “mad” in late-medieval Germany. It is a straightforward recitation of accounts of the mentally ill taken from state archives that is still consulted by historians of late medieval and early modern Germany. What is up for debate is whether Foucault uses these records selectively to craft a narrative around the “ship of fools”.
The problem, as noted by the historian H. C. Erik Midelfort and others, is that Foucault has to stretch to interpret the periodic transport by river of the mentally ill as a real-life example of the “ship of fools”. Even Foucault’s most enthusiastic supporters, including Greg Gutting, acknowledge that the evidence is thin and that the mere use of water-based transportation to remove those deemed undesirable from one settlement to another is not quite the same thing as a peripatetic vessel inhabited solely by the “mad”.
Historians also tend to criticize Foucault for omitting evidence that contradicts his claims—for instance, the introduction of spaces of confinement such as prisons for the insane in 14th and 15th century Germany. As Foucault aims to construct an argument about the shift from transportation to confinement in the early modern period, he often fails to acknowledge the examples mentioned in Kirchhoff’s text.
A near-contemporary of Foucault who also makes use of Kirchhoff’s work is George Rosen. Rosen’s project is a more traditional history of mental illness that dispenses with Foucault’s romantic notion of the “ship of fools”. Rosen also does not fail to mention examples of confinement in the late medieval period, arguing that these two treatments for insanity have long been in use simultaneously.
In fact, both confinement to institutions and transportation continued to co-exist into the late modern era. Transportation, euphemistically renamed as “traveler’s aid” in 20th century America, was used as a method to expel the mentally ill, the homeless, and others deemed undesirable from a city—though the boat was replaced by a train, bus, or airplane.
SOURCES:
Foucault, Michel. Folie et déraison: Histoire de la folie à l'âge classique. Paris: Plon, 1961.
Gutting, Gary. “Foucault and the History of Madness”, in The Cambridge Companion to Foucault. Gary Gutting, ed. Cambridge: Cambridge University Press, 2005.
Kirchhoff, Theodor. Grundriss einer Geschichte der deutschen Irrenpflege. Berlin: Hirschwald, 1890.
Midelfort, H. C. Erik. "Madness and Civilization in Early Modern Europe: A Reappraisal of Michel Foucault", in After the Reformation: Essays in Honor of J. H. Hexter. Barbara C. Malament, ed. Philadelphia: University of Pennsylvania Press, 2016.
Rosen, George. “The Mentally Ill and the Community in Western and Central Europe During the Late Middle Ages and the Renaissance,” Journal of the History of Medicine and Allied Sciences 19, no. 4 (1964): 377–88.