It gets worse. This isn’t a randomly selected example—it’s specifically selected as a case where reason would have a hard time noticing when and how it’s making things worse.
Well, the history of bringing manioc to Africa is not the only example. Scientific understanding of human nutrition (alongside with disease) had several similar hiccups along the way, several which have been covered in SSC (can’t remember the post titles where):
There was a time when Japanese army lost many lives to beriberi during Russo-Japanese war, thinking it was a transmissible disease, several decades [1] after the one of the first prominent Japanese young scholars with Western medical training discovered it was a deficiency related to nutrition with a classical trial setup in Japanese navy (however, he attributed it—wrongly—to deficiency of nitrogen). It took several decades to identify vitamin B1. [2]
Earlier, there was a time when scurvy was a problem in navies, including the British one, but then British navy (or rather, East India Company) realized citrus fruits were useful preventing scurvy, in 1617 [3]. Unfortunately it didn’t catch on. Then they discovered it again with an actual trial and published the results, in 1740-50s [4]. Unfortunately it again didn’t catch on, and the underlying theory was also as wrong as the others anyway. Finally, against the scientific consensus at the time, the usefulness of citrus was proven by a Navy read admiral in 1795 [5]. Unfortunately they still did not have proper theory why the citrus was supposed to work, so when the Navy managed to switch to using lime juice with minimal vitamin C content [6], then managed reason themselves out of use of citrus, and scurvy was determined as a result of food gone bad [7]. Thus Scott’s Arctic expedition was ill-equipped to prevent scurvy, and soldiers in Gallipoli 1915 also suffered from scurvy.
Story of discovering vitamin D does not involve as dramatic failings, but prior to discovery of UV treatment and discovery of vitamin D, John Snow suggested the cause was adulterated food [8]. Of course, even today one can easily find internet debates about what is “correct” amount of vitamin D supplement if one has not sunlight in winter. Solving B12 deficiency induced anemia appears a true triumph of the science, as a Nobel prize was awarded for dietary recommendation for including liver in the diet [9] before B12 (present in liver) was identified [10].
Some may notice that we have now covered many of the significant vitamins in human diet. I have not even started with the story of Semmelweis.
And anyway, I dislike the whole premise of casting the matter about “being for reason” or “against reason”. The issue with manioc, scurvy, beriberi, and hygiene was that people had unfortunate overconfidence in their per-existing model of reality. With sufficient overconfidence, rationalization or mere “rational speculation”, they could explain how seemingly contradictory experimental results actually fitted in their model, and thus claim the nutrition-based explanations as an unscientific hogwash, until the actual workings of vitamins was discovered. (The article [1] is very instructive about rationalizations Japanese army could come up to dismiss Navy’s apparent success with fighting beriberi: ships were easier to keep clean, beriberi was correlated with spending time on contact with damp ground, etc.)
While looking up food-borne diseases while writing this comment, I was reminded about BSE [11], which is hypothesized to cause vCJD in humans because humans thought it was a good idea to feed dead animals to cattle to improve nutrition (which I suppose it does, barring prion disease). I would view this as a failing from not having a full model what side-effects behavior suggested by the partial model would cause.
On the positive side, sometimes the partial model works well enough: It appears that miasma theory of disease like cholera was the principal motivator for building modern sewage systems. While it is today obvious cholera is not caused by miasma, getting rid of smelly sewage in orderly fashion turned out to be a good idea nevertheless [12].
I am uncertain if I have any proper suggested conclusion, except for that, in general, mistakes of reason are possible and possibly fatal, and social dynamics may prevent proper corrective action for a long time. This is important to keep in mind when making decisions, especially novel and unprecedented, and when evaluating the consequences of action. (The consensus does not necessarily budge easily.)
Maybe a more specific conclusion could be: If one has only evidently partial scientific understanding of some issue, it is very possible acting on it can have unintended consequences. It may even not be obvious where the holes in the scientific understanding are. (Paraphrasing the response to Semmelweis: “We don’t exactly know what causes childbed fever, it manifests in many different organs so it could be several different diseases, but the idea of invisible corpse particles that defy water and soap is simply laughable.”)
Well, the history of bringing manioc to Africa is not the only example. Scientific understanding of human nutrition (alongside with disease) had several similar hiccups along the way, several which have been covered in SSC (can’t remember the post titles where):
There was a time when Japanese army lost many lives to beriberi during Russo-Japanese war, thinking it was a transmissible disease, several decades [1] after the one of the first prominent Japanese young scholars with Western medical training discovered it was a deficiency related to nutrition with a classical trial setup in Japanese navy (however, he attributed it—wrongly—to deficiency of nitrogen). It took several decades to identify vitamin B1. [2]
Earlier, there was a time when scurvy was a problem in navies, including the British one, but then British navy (or rather, East India Company) realized citrus fruits were useful preventing scurvy, in 1617 [3]. Unfortunately it didn’t catch on. Then they discovered it again with an actual trial and published the results, in 1740-50s [4]. Unfortunately it again didn’t catch on, and the underlying theory was also as wrong as the others anyway. Finally, against the scientific consensus at the time, the usefulness of citrus was proven by a Navy read admiral in 1795 [5]. Unfortunately they still did not have proper theory why the citrus was supposed to work, so when the Navy managed to switch to using lime juice with minimal vitamin C content [6], then managed reason themselves out of use of citrus, and scurvy was determined as a result of food gone bad [7]. Thus Scott’s Arctic expedition was ill-equipped to prevent scurvy, and soldiers in Gallipoli 1915 also suffered from scurvy.
Story of discovering vitamin D does not involve as dramatic failings, but prior to discovery of UV treatment and discovery of vitamin D, John Snow suggested the cause was adulterated food [8]. Of course, even today one can easily find internet debates about what is “correct” amount of vitamin D supplement if one has not sunlight in winter. Solving B12 deficiency induced anemia appears a true triumph of the science, as a Nobel prize was awarded for dietary recommendation for including liver in the diet [9] before B12 (present in liver) was identified [10].
Some may notice that we have now covered many of the significant vitamins in human diet. I have not even started with the story of Semmelweis.
And anyway, I dislike the whole premise of casting the matter about “being for reason” or “against reason”. The issue with manioc, scurvy, beriberi, and hygiene was that people had unfortunate overconfidence in their per-existing model of reality. With sufficient overconfidence, rationalization or mere “rational speculation”, they could explain how seemingly contradictory experimental results actually fitted in their model, and thus claim the nutrition-based explanations as an unscientific hogwash, until the actual workings of vitamins was discovered. (The article [1] is very instructive about rationalizations Japanese army could come up to dismiss Navy’s apparent success with fighting beriberi: ships were easier to keep clean, beriberi was correlated with spending time on contact with damp ground, etc.)
While looking up food-borne diseases while writing this comment, I was reminded about BSE [11], which is hypothesized to cause vCJD in humans because humans thought it was a good idea to feed dead animals to cattle to improve nutrition (which I suppose it does, barring prion disease). I would view this as a failing from not having a full model what side-effects behavior suggested by the partial model would cause.
On the positive side, sometimes the partial model works well enough: It appears that miasma theory of disease like cholera was the principal motivator for building modern sewage systems. While it is today obvious cholera is not caused by miasma, getting rid of smelly sewage in orderly fashion turned out to be a good idea nevertheless [12].
I am uncertain if I have any proper suggested conclusion, except for that, in general, mistakes of reason are possible and possibly fatal, and social dynamics may prevent proper corrective action for a long time. This is important to keep in mind when making decisions, especially novel and unprecedented, and when evaluating the consequences of action. (The consensus does not necessarily budge easily.)
Maybe a more specific conclusion could be: If one has only evidently partial scientific understanding of some issue, it is very possible acting on it can have unintended consequences. It may even not be obvious where the holes in the scientific understanding are. (Paraphrasing the response to Semmelweis: “We don’t exactly know what causes childbed fever, it manifests in many different organs so it could be several different diseases, but the idea of invisible corpse particles that defy water and soap is simply laughable.”)
[1] https://pubmed.ncbi.nlm.nih.gov/16673750/
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3725862/
[3] https://en.wikipedia.org/wiki/John_Woodall
[4] https://en.wikipedia.org/wiki/James_Lind
[5] https://en.wikipedia.org/wiki/Alan_Gardner,_1st_Baron_Gardner
[6] https://en.wikipedia.org/wiki/Scurvy#19th_century
[7] https://idlewords.com/2010/03/scott_and_scurvy.htm
[8] https://en.wikipedia.org/wiki/Rickets#History
[9] https://www.nobelprize.org/prizes/medicine/1934/whipple/facts/
[10] https://en.wikipedia.org/wiki/Vitamin_B12#Descriptions_of_deficiency_effects
[11] https://en.wikipedia.org/wiki/Bovine_spongiform_encephalopathy
[12] https://en.wikipedia.org/wiki/Joseph_Bazalgette