Ragwort podcast Professor Mick Crawley Imperial College London

 This is one of those occasions when I am actually going to sing the praises of someone. The moment I started to write this entry a particular Latin phrase jumped into my head Res Ipso Loquitor, Its modern use is a rather obscure legal use but its meaning is extremely apt for this matter. It means "The thing speaks for itself," and it does!. The podcast is a clear explanation by an internationally renowned expert of  ragwort hysteria, the subject of this blog. I  already knew about this man's expertise and his eloquence in explaining things is unsurprising but it was an extra bonus to hear him speaking. He speaks with the resonant dulcet  tones you would expect from an actor who is employed as a narrator on a television documentary. Please do go and spend the time to listen to the podcast which I will link to

I am going to quote and add some comments to a small section of a transcript of the podcast. It is one of a series of podcasts from the Knepp Wildland  and features the expert Professor Mick Crawley of Imperial College London being interviewed by the project's co-owner and author of the brilliant book Wildling, Isabella Tree.

It begins with an introduction

Isabella Tree:

Hello, and welcome to the Knepp Wildland podcast with me, Isabella Tree — author, conservationist, it and co-owner of the Knepp Rewilding Project.

This month we’re discussing a plant that is probably the most controversial native wildflower in the British Isles. It’s been a spectacular summer for common ragwort. You may have seen it erupting in fields near you, on roadside verges, in urban parks — anywhere there’s a scrap of space for it.

People either love it, or they absolutely hate it and want it erased from the face of the planet.

So to get to the bottom of these intense ragwort passions, and to try and nail down some facts, I’m standing in acres and acres of ragwort in the middle of Knepp, with our old friend Mick Crawley, Emeritus Professor of Plant Ecology at Imperial College London — who probably knows more about ragwort than anyone else on the planet. So lovely to see you, Mick.

After introducing the plant we get on to this piece.

Isabella Tree:

So before we get into why people hate it, let’s describe the benefits. Why do we love ragwort here at Knepp?

Mick Crawley:

There are two ways insects benefit from ragwort. One is by eating it — there are two very important species that do, and about 20 others that depend on it but don’t affect its growth much.

The other, more widespread benefit is from its nectar and pollen. Dozens of species — bees, flies, butterflies, moths, beetles — rely on it, especially because of its timing.

Isabella Tree:

Yes, I’ve read it flowers when little else is available.

Mick Crawley:

Exactly. It’s late-flowering, and can last into October or November. For nectar-feeding insects at this time of year, it’s a lifeline.

Isabella Tree:

And that incredible acid-yellow colour of its flowers is visible even to night-flying moths — some of our best pollinators.

So we have this wonderful, hugely beneficial native wildflower. And yet, every year at Knepp, when ragwort comes into bloom, we brace ourselves for the hate mail — people accusing us of being irresponsible, even of deliberately trying to kill animals. What’s going on here?

Mick Crawley:

I don’t think any plant has more fake news about it than ragwort. 

And that fake news is exactly what I blog about here and despite it being debunked , we find the Facebook posting of this podcast has been full of people who either didn't bother to listen to the podcast at the top of the post OR just didn't understand it, repeating the fake news and even refusing to believe people who are telling them they are wrong with good evidence. 

It continues:-

Isabella Tree:

I wonder if part of the myth comes from the Injurious Weeds Act. Ragwort was listed along with creeping and spear thistles and docks as an injurious weed to be controlled for farming. That lodged in people’s minds — that it’s a poisonous plant that shouldn’t exist anywhere.

Now just for clarification that law is actually called the Weeds Act and "injurious" in this case actually means, exactly what was defined in the Agriculture Act 1920 and that was something that was harmful to the interests' of arable agriculture back then. It doesn't mean causes injury and the other plants are on lists of wild foods that can be eaten harmlessly by people who go foraging.

Then we get this correct interpretation of this law, as regular readers will know

Mick Crawley:

That’s right — but it’s not illegal to have ragwort.

Isabella Tree:

Exactly. But people insist landowners are legally obliged to remove it everywhere.

Mick Crawley:

Which is completely untrue. In fact, government guidance says it shouldn’t be removed from nature — it’s far too beneficial.

Another important section is this

Mick Crawley:

 Cutting off flowers before seed sets reduces the death rate, because the plant keeps its root reserves and grows again next year — turning a biennial into a perennial.

Pulling the plant up leaves broken root fragments in the soil, each producing a new rosette. So instead of killing one plant, you multiply it by four or five.

The only sure way to kill ragwort is to let it flower and set seed. Once it invests all its root reserves into reproduction, it dies. Counterintuitive, but true.

Isabella Tree:

That is counterintuitive. And yet people blame us for ragwort spreading into their gardens miles away — which isn’t how it works.

Mick Crawley:

Right. Experiments show that adding extra ragwort seed to grassland makes no difference — recruitment isn’t seed-limited. It’s disturbance-limited. Seeds falling on intact grassland mostly die in the shade. For new plants to establish, you need disturbance: pig rooting, rabbit scrapes, cattle hoof prints. That’s why ragwort thrives here at Knepp.

At Silwood Park in Berkshire, where I work, we haven’t had ragwort for six years — because rabbit haemorrhagic disease wiped out the rabbits, and without their disturbance, ragwort can’t establish.

Isabella Tree:

So when people see ragwort, it’s not “blown in” from elsewhere — it’s come from the seed bank under their feet, triggered by some disturbance.

Mick Crawley:

Exactly.

Just to expand on this recruitment thing. This is about individuals being recruited into a population rather like the army recruits people into their population of soldiers. so to clarify this with a more detailed explanation. Scientists have tried adding extra ragwort seeds to grassland, but it makes no difference this is because there are already plenty of seeds around. There are plenty of seeds of this plant all over the place but that most of them can’t get started. When seeds land on thick and unbroken grass, they usually die in the shade. For new ragwort plants to grow, the ground has to be disturbed a bit like when pigs root around, rabbits dig, or cattle leave hoofprints. These bare patches let the seeds see the light and take root. That’s why ragwort does so well at Knepp, where animals are free to roam and stir up the soil.

Oh and before I finish while the podcast diplomatically says it is mystery where the fake news comes from . Regular readers here will know precisely where it comes from.  In my honest opinion most of it comes from the officers and the staff of the British Horse Society!

As you can see this podcast is all really excellent stuff and there are many other good points in the complete podcast. So I urge you all, please, please go and listen to it. It really is excellent, So go to the website of the Knepp project and listen to the complete thing. It is well worth your time. Episode 39: The Plant People Love to Hate - Knepp

Dr David Marlin more ragwort nonsense!

 I have written before about Dr David Marlin making questionable or unwarranted claims about ragwort and I am sad to say that he is at it again. So once again I am offering my honest opinion on what he has said based on the scientific evidence and legal facts. He has posted something on his website and on social media which is contains unsubstantiated assertions alongside factual errors and misleading assumptions.

I’m not claiming that Dr. Marlin is deliberately misleading people. That would not be rational as I cannot read his mind and gain  insight into his private thoughts. What I can say, with confidence, is that his statements about ragwort are not supported by the best available evidence, and they mirror the kind of reasoning errors we often see in cases where strong emotion overrides sound evaluation of facts.

I am going to analyse the post he has made line by line, or perhaps more accurately piece by piece.

."Do Equestrians Want to Eliminate Ragwort from the Countryside?

Short answer: No. Just from the places horses graze!"

Well on the basis of the scientific literature there is little risk to horses in well managed pastures from the occurrence of ragwort in it. They eat around it. 

"Most horse owners aren’t bothered about ragwort on verges, arable field margins, or in wild meadows, as the image above shows. We only want it removed from places where horses graze (or where hay and haylage for horses are being grown). That’s not scaremongering. That’s animal welfare."

Social media is full of people acting exactly as if they want ragwort eliminated and Prof Knottenbelt has said so in an on-line CV and is quoted in a Guardian article that it is his aim. Also to make the point again there is no proper evidence of risk just from it being in a pasture.

"Ragwort and Horses: What the Science Actually Says

Ragwort contains pyrrolizidine alkaloids (PAs) — toxic compounds that cause irreversible liver damage in horses if ingested in sufficient amounts.

This damage from PAs IS cumulative: While PAs are not stored, the liver damage caused by them is cumulative and irreversible."

NO not necessarily. The biochemistry shows that there are repair mechanisms for early damage and there are several published scientific papers showing no harm at low doses of the toxic alkaloids

"Ingestion of as little as 1% of bodyweight in ragwort, whether fresh or dried in hay, can prove fatal over time."

This is not supported by the evidence at all. No reference is given for this BUT he made the same claim in a Facebook post and then he gave a reference.  It is probably best If I just repeat the points I made then.

As little ragwort as 1% of bodyweight can prove fatal over time - Fu, P. P., Q. Xia, G. Lin & M. W. Chou. 2004. Pyrrolizidine alkaloids - Genotoxicity, metabolism enzymes, metabolic activation, and mechanisms. Drug Metabolism Reviews 36: 1-55.

Just look at this reference! As soon as I saw it I was on the alert. I am very familiar with this paper. It DOES NOT SAY THAT! It is not about that kind of thing at all. What is going on here? Is this just carelessness or is it a deliberate attempt to mislead? In my honest opinion if someone wanted to bamboozle people with bad science this is exactly the sort of paper that would be used it is 55 pages long and full of degree level biochemistry.  In fact it is worse than that. I took a random sample of text and put it through something that calculates a measure of readability called the Gunning Fog  Index where Fog stands for Frequency Of Gobbledegook. An index of 17 requires you to have a university degree but this actually came out at 19.5! Most people wouldn’t have a clue about what it says. The word “ragwort” does not even appear in this scientific paper!

On the basis of what I have read in over 2 decades of detailed study of what is known from the scientific literature, claiming that 1% of body weight  being fatal is I something I can honestly describe as scaremongering.

It’s estimated that up to 8% of equine liver samples submitted to labs show signs of ragwort-related pathology.

Vets across the UK continue to report suspected and confirmed cases of ragwort poisoning each year.

So no, this isn’t fake news or hysteria. It’s a fact, backed by published data, veterinary reports, and decades of pathology.

This is not what decades of pathology says at all. There are vets that don't know this, but it is an established scientific fact that the diagnosis is not this simple. To quote a paper from one of the worlds most highly prestigious scientific journals, Nature, that toxins produced by often invisible moulds that occur on preserved forage are, "Indistinguishable from ragwort.." This was decades ago in 1961, but it is still reflected in the text of some of the better veterinary textbooks and has never been superseded by more recent research.

One of the primary issues that emerges in this subject is what is known as moral panic where emotions such as fear and disgust override rational thinking  and ill thought out postings such as these from Dr David Marlin only serve to fuel this. Science is more about nuance, abstract ideas, and evidence than these simple hyped up and exaggerated claims.

Then there are a set of false claims about the law

"A Reminder About Ragwort and UK Law!

Ragwort is one of five “injurious weeds” covered by the 1959 Weeds Act. The other weeds covered by this act are Spear Thistle, Field Thistle, Curled Dock and Broad-Leaved Dock."

Injurious in this context means harmful to agriculture.

"The law states that……

If you own horses, ponies or livestock, you must not allow them to graze on land where you know ragwort is present.”

It says no such thing. 

This is the only relevant piece of text in the law. "Where the Minister of Agriculture, Fisheries and Food (in this Act referred to as “the Minister”) is satisfied that there are injurious weeds to which this Act applies growing upon any land he may serve upon the occupier of the land a notice in writing requiring him, within the time specified in the notice, to take such action as may be necessary to prevent the weeds from spreading."

Sp to explain it the law says that you may be issued wth a control notice, these are rare. If you re issued with one of those notices, then you have to control ragwort. In the absence of one of these notices, there is no requirement placed on anyone to do anything. Horses are not even mentioned!

“You can be prosecuted if you allow animals to suffer by eating harmful weeds.”

Yes you might but as we've heard they don't eat the fresh plant unless starved. So we're back to hay again about which there is no dispute,

A link at the end is made to the government website as if this were the statute law. It is not! it is marked clearly as guidance. In a posting a few weeks ago I gave the key risk statistics to an independent evaluator the AI ChatGPT asking it in unbiased stages to evaluate the risk statistics used to justify ragwort control and it was scathing about it. The guidance issued by government is simply wrong!

Mythbusting the “Native Superflower” Narrative

“It’s not a cumulative poison.”

WRONG. While PAs are not stored, the liver damage caused by them is cumulative and irreversible.

This is based on a complete misunderstanding of the biochemistry and terminology. As I've said here are repair mechanisms so damage is not caused by small doses but he is not using the word cumulative correctly in the context. Alcohol can cause steady and increasing damage to the liver but we talk about chronic poisoning not cumulative poisoning because the alcohol doesn't stay n the body. Cumulative poisons are things like lead or cadmium that do not  leave the body and build up in it.

 It is a standard part of toxicology. Such a basic part that in most sources it is implied over a number of pages rather than stated as a definition as it is such a basic concept that it is assumed  to be known.

Firstly the Oxford English Dictionary which is the definitive dictionary of the English language defines cumulative in this context as _

  :-

Constituted by or arising from accumulation, or the accession of successive portions or particulars; acquiring or increasing in force or cogency by successive additions

:-

So the dictionary definition proves him wrong as the poison itself does not build up.

This  definition from a scientific paper confirms it. 

" Cumulative poison is a slow acting poison, which has not been fully discarded from the system. It retains in the tissues for a number of years and therefore contaminates not only the tissues but also at the level of cell too." ( Sud S. Diagn Ther Complement Tradit Med 2019(1): 01-02.)

"“It can’t penetrate human skin.”

Also WRONG. PA absorption through skin is low, but not zero, and handling ragwort regularly without gloves can cause liver damage."

This is just an extension of the false claim that it is a cumulative poison combined with the false idea that every dose has an effect which as we see above isn't the case. The idea that ragwort is poisonous to the touch like this was debunked by some Dutch scientists, one of whom has a PhD on the plant, some years ago.

“It’s not invasive.”

TRUE. It isn’t invasive by definition, BUT that doesn’t mean it can’t spread.

Each ragwort plant produces up to 200,000 wind-dispersed seeds, and these can travel many metres or even kilometres with secondary movement (e.g. water, animals, hay contamination).

An advert claiming just 150,000 seeds was banned some years ago by the Advertising Standards Authority and the seed calculations in the best scientific paper show the figures are much lower, which is why the ad was banned.

In fact the proper statistics show that typically a plant produces far fewer seeds than even that. There is no scientific basis for the claim that seeds are regularly dispersed over distances measured in kilometres by the wind, most in fact falling after a few metres and the occasional and rare outlier doesn't justify the exaggerated fear provoking  claims Secondary dispersal is not at all significant in reality. This is another example of overstating things seemingly to create fear rather than to promote understanding

As Peter Medawar, the Nobel Prize winner, once remarked, “The spread of secondary and latterly of tertiary education has created a large population of people, often with well-developed literary and scholarly tastes, who have been educated far beyond their capacity to undertake analytical thought.”

This quote seems rather relevant today as there are people in the veterinary and  in the equine communities who often speak very confidently and use scientific language. However, they repeatedly seem to show a cognitive failure to engage with the proper scientific concepts in a critical or careful manner. The ability to cite papers, use technical terms or make the firm pronouncements which we so often see does not necessarily  reveal a proper analytical depth in understanding issues. In these scientific debates where we deal with such important issues as ecological and welfare concepts extreme care must be taken not to conflate verbal polish with proper scientific cognitive rigour. 

Ragwort Debates and Authoritarian Behaviour

 One of the most consistent thing that  I’ve encountered during the more than  two decades that I have  studying ragwort, its ecology, toxicology, etc, is that conversations about this plant very often take on an authoritarian tone.

I don’t mean the sorts of  people who wear jackboots , although some of the attackers definitely meet the definition of far right trolls,  but rather a certain  type of rigid mindset that appears over and over again in online postings, public commentary, and even in important  policy documents. So having studied this  I think it’s worth mentioning some of the reasons  why this happens and as I'll show it leads to poor information being disseminated.

Psychologists who have studied it define authoritarianism not merely as a political stance but as a cognitive style. Its  nature is characterised by:

• Deference to authority figures

• Hostility toward dissent or ambiguity

• A preference for certainty, control, and clear rules

This  scientific framework is well-documented in Canadian scientist Dr Bob Altemeyer's work on Right-Wing Authoritarianism  from which I will show a large quote  in a section below,

In ragwort debates, this often manifests as:

• Appeals to status over evidence ("He’s a vet, you’re not")

• Harsh reactions to being questioned ("Stop spreading misinformation")

• Misuse of rules and laws to assert control ("You’re legally required to remove that") It's generally not true with regard to ragwort anyway

• Dismissal of uncertainty or nuance ("It’s poisonous, so it must be dangerous")

The issue here is that ragwort pushes several psychological buttons:

• Fear: It is widely believed to be a serious poison, especially to horses. Largely as I show due to false information from equine organisations.

• Control: It grows in unmanaged spaces, often defying neat control measures.

• Tradition: It has become a kind of symbolic enemy in some  of those narratives that surround land management 

When people perceive that there is a threat whether it is real or not, and especially when it concerns animal welfare, a subject that is almost bound to give rise to emotional arguments, it’s natural for some people to want simple answers and clear action. However, it is the case that desire often overrides careful reasoning and that is quite simply a problem for society. 

So when someone like me comes along and says, "Yes, it's toxic, but the science doesn't support the hysteria," the reaction isn't just to disagree with it. I find there is  often moral outrage, which leads to me being abused and attacked  as if questioning the narrative is dangerous in itself.

I've seen it time and again this kind of poor reasoning accompanied with the most illogical statements.

• People objecting to Freedom of Information requests and claiming they're a "waste of official time"

• Individuals insisting that because a respected vet made a claim, it must be true

• Accusations that questioning public messaging is "dangerous"

• Dismissals of scientific studies as "too old" when they're still valid and widely cited 

For example, Harper & Wood’s 1957 study is still  very relevant and cited today in scientific literature. It is clear to anyone with proper reasoning ability that longevity alone doesn't invalidates scientific findings. Let's remember that we still learn Newton's laws which come from the late 1600s!

Sometimes it is so irrational that even minor corrections (like a typo or small logically irrelevant wrong number) are jumped upon with glee on the quite incorrect assumption that they undermine my position.

It is worth noting in this context  that authoritarian thinking tends to correlate with lower educational attainment. This is particularly so in fields that emphasize critical thinking and openness to complexity. The research demonstrates that individuals with higher education and in particular those who score high in the well established and studied personality dimension of openness to experience  tend to  to tolerate ambiguity and question traditional hierarchies.  Studying  complex ideas and the concepts around them are often their idea of fun. This is me. I identify strongly with this sort of behaviour and thinking.

Something I have noticed quite often is many of the people who make the most rigid arguments in ragwort debates also show basic literacy errors and  also a tendency to rely on memorised claims rather than reasoned evidence. Of course, spelling errors alone don’t indicate authoritarianism, and  in my  case spelling errors can and do sometimes creep in, but poor literacy can be a sign of gaps in the kinds of reasoning skills that protect against it.

This is a serious problem because authoritarian reasoning stifles scientific discourse. It replaces open debate with really poor thinking.

If we are to care about  understanding the issues and the science properly  then, naturally,  we need to resist this style of thought. It's of course  entirely possible to take plant toxicity seriously without falling prey  to exaggerated fear or rigid dogmatic thinking. However, this blog exists because so many people do just that with all sorts of crazy claims having been made.

Ragwort isn't just a ecologically very important wildflower. It's become a symbol onto which people project all sorts of irrational and illogical thinking . We find that when those things get challenged, the reaction is all too often highly emotional and so often it is not about about the facts.

It is an essential part of its nature that science thrives on questions. It is crucial and important that we must be free to ask them without being accused of endangering society every time we point out that the emperor, or the expert, might just not have all the clothes that some poor reasoners would think that they have.

These people rely  so far  too much on concrete thinking that abstract ideas and complexity are invisible to them. I often joke to myself that the concrete starts at one ear and ends at the other!

Here is the extract from Dr Altemayer's  work illustrating the all too typical poor thinking that frustrates me when dealing with these people. Research shows that this sort of personality has poor creativity and rarely succeeds in the complex world of scientific endeavours.

 I should also explain that RWA in his text, means Right Wing Authoritarian. It has not escaped my attention that when I examined a certain word in the copy of the Oxford English Dictionary , the definitive dictionary of the English language, in my local library  that the definition included  the phrase, "a person of right wing authoritarian views."  If you haven't already guessed,  that word is "fascist." I would hasten to say of course that not all the people whose bad thinking I criticise here would necessarily fall into that camp, but I do know that some of them do.

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 Sitting in the jury room of the Port Angeles, Washington court house in 1989,  Mary Wegmann might have felt she had suddenly been transferred to a parallel  universe in some Twilight Zone story. For certain fellow-jury members seemed to  have attended a different trial than the one she had just witnessed. They could not  remember some pieces of evidence, they invented evidence that did not exist, and they  steadily made erroneous inferences from the material that everyone could agree on.

 Encountering my research as she was later developing her Ph.D. dissertation project, she suspected the people who “got it wrong” had been mainly high RWAs. So she  recruited a sample of adults from the Clallam County jury list, and a group of students  from Peninsula College and gave them various memory and inference tests. For  example, they listened to a tape of two lawyers debating a school segregation case on  a McNeil/Lehrer News Hour program. Wegmann found High RWAs indeed had more  trouble remembering details of the material they’d encountered, and they made more  incorrect inferences on a reasoning test than others usually did. Overall, the  authoritarians had lots of trouble simply thinking straight.  Intrigued, I gave the inferences test that Mary Wegmann had used to two large samples of students at my university. In both studies high RWAs went down in flames  more than others did. They particularly had trouble figuring out that an inference or  deduction was wrong. To illustrate, suppose they had gotten the following syllogism:

 All fish live in the sea.

 Sharks live in the sea.

Therefore, sharks are fish.

 The conclusion does not follow, but high RWAs would be more likely to say the reasoning is correct than most people would. If you ask them why it seems right, they  would likely tell you, “Because sharks are fish.” In other words, they thought the  reasoning was sound because they agreed with the last statement. If the conclusion is right, they figure, then the reasoning must have been right. Or to put it another way,  they don’t “get it” that the reasoning matters--especially on a reasoning test. 

 This is not only “Illogical, Captain,” as Mr. Spock would say, it’s quite  dangerous, because it shows that if authoritarian followers like the conclusion, the  logic involved is pretty irrelevant. The reasoning should justify the conclusion, but for  a lot of high RWAs, the conclusion validates the reasoning. Such is the basis of many a prejudice, and many a Big Lie that comes to be accepted. Now one can easily overstate this finding. A lot of people have trouble with syllogistic reasoning, and high RWAs are only slightly more likely to make such mistakes than low RWAs are. But in general high RWAs seem to have more trouble than most people do realizing that a conclusion is false. 

Deductive logic aside, authoritarians also have trouble deciding whether empirical evidence proves, or does not prove, something. They will often think some thoroughly ambiguous fact verifies something they already believe in. So if you tell them that archaeologists have discovered a fallen wall at ancient Jericho, they are more likely than most people to infer that this proves the Biblical story of Joshua and the horns is true--when the wall could have been knocked over by lots of other groups, or an earthquake, and be from an entirely different era (which it is).

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This is good stuff and if you like it then the good Dr has made it available for free for you to read as a free download.  Don't let the fact that it is free make you think it is of less value. He actually warns against that irrational conclusion. I suspect strongly that he has a good wage or pension and is keen for as many people to read his work as possible, Remember It can be found here on his website The Authoritarians

What an AI makes of Defra's ragwort Code of Practice. It is scathing!

AI has its issues and it can raise concern such as is it putting people out of work, However it can prove a powerful tool in evaluating evidence and finding bits of research that might be difficult to find. I often think of it as "Alien Intelligence," as it is much different to human intelligence.

What I have done here is ask three questions. The first one is a real quote from DEFRA's guidance on ragwort control and it is the absolutely key factor in how they establish and promote the amount and rate of ragwort poisoning. The "he" in the quote is Professor Derek Knottenbelt who has also been quoted rather ridiculously as claiming that ragwort is poisoning the Cinnabar moth, which I hasten to say is NOT the main reason that ragwort is an ecologically valuable wildflower.

Here I have used ChatGPT as an independent evaluator of the policy. At first it points out the strength and weaknesses of DEFRA's statements. Then, when it is supplied the actual data obtained from Freedom of Information requests it points out it is completely wrong to use the data and when I tell it that the sentence is from government advice then it  becomes really scathing about the bad science. I quote the responses entirely as a cut and paste from the output of this clever computer program. I have only labelled the questions for clarity

Question 1

What can you tell me about the logic and reasoning in the following statement? "He has estimated a figure of 500 horse deaths from ragwort poisoning in 2000. This figure is based on the number of confirmed horse deaths from ragwort poisoning seen by the Philip Leverhulme Large Animal Hospital Teaching Hospital at Liverpool University as a percentage of all the horse cases treated during the ear, and grossed up to be representative of the total horse population."

ChatGPT said:

The statement presents an estimate of horse deaths from ragwort poisoning using inductive reasoning based on extrapolation. Here's a breakdown of the logic and reasoning behind it, including both its strengths and potential flaws:

---

🔍 Summary of the Logic

1. Observed Data Source:

   • A specific number of confirmed horse deaths from ragwort poisoning were observed at a single veterinary hospital (Liverpool University's Philip Leverhulme Large Animal Teaching Hospital).

2. Proportional Estimation:

   • This number is taken as a proportion of total horse cases treated at that hospital during 2000.

3. Extrapolation:

   • The proportion is then "grossed up" (i.e., scaled) to estimate the number of deaths across the entire horse population in the UK (or another broader context).

---

✅ Logical Strengths

• Use of empirical data: The estimate is grounded in actual confirmed cases, not speculation.

• Methodical scaling: Applying a proportion to a larger population is a common statistical technique when comprehensive data isn't available.

---

❌ Logical Weaknesses and Concerns

1. Sampling Bias:

   • The Liverpool hospital's cases may not be representative of the whole UK horse population.

   • Horses seen at a teaching hospital could have more severe or unusual conditions, potentially overestimating rare events like ragwort poisoning.

2. Confirmation Bias:

   • Only confirmed cases were counted. Ragwort poisoning is difficult to diagnose definitively, so the actual number of cases may be underreported, or misdiagnosed, affecting reliability.

3. Assumption of Uniformity:

   • It assumes the same rate of ragwort poisoning applies uniformly across all horse populations in different regions, which is unlikely (as environmental exposure varies).

4. Small Sample Size Risk:

   • If the number of observed cases was small, the resulting estimate could have high variance and large margins of error when extrapolated.

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🧠 Type of Reasoning

• Inductive Reasoning: Drawing general conclusions (nationwide deaths) from specific observations (hospital cases).

• Statistical Estimation: Involves proportional scaling and population inference.

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🧮 Example Analogy

Imagine seeing 2 red cars in a dealership that sells 10 cars and concluding that 20% of all cars in the country are red, then scaling that to millions of cars. That only works if your sample (the dealership) is representative — otherwise, your extrapolation may be way off.

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📌 Conclusion

The reasoning shows a structured attempt to estimate a figure from limited data, but it relies heavily on the representativeness of a single data source, which is a major potential flaw. It's a reasonable starting point, but not robust enough to be definitive without additional, more representative data.

Question 2

You said:

What can you tell me if I say that a Freedom of Information request to the hospital actually shows only one case in an eight year period?

ChatGPT said:

If a Freedom of Information (FOI) request to the hospital reveals only one case of ragwort poisoning in an eight-year period, it severely undermines the credibility and validity of the original estimate of 500 horse deaths in a single year. Here's a detailed analysis of what that implies:

---

🔍 What This New Information Reveals

1. Factual Discrepancy:

   • The original estimate was supposedly based on a meaningful number of confirmed deaths at that hospital in 2000.

   • But if only one case occurred over eight years, then the hospital could not possibly have had a significant enough sample in 2000 to justify such extrapolation.

2. Invalid Assumptions:

   • The method described (taking the hospital’s confirmed ragwort deaths as a proportion and scaling up) relies on false or exaggerated input data.

   • This suggests that either:

     • The original estimator misunderstood or misrepresented the hospital data.

     • Or the methodology was used in bad faith (deliberately misleading).

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❌ Logical and Ethical Consequences

• Flawed Reasoning:

  • The extrapolation logic collapses entirely if the base figure is incorrect or negligible.

• Inflated Estimate:

  • The claim of 500 deaths is now shown to be not just imprecise but likely unfounded.

• Potential Misinformation:

  • Such a statement, if made in a policy or advocacy context, could be highly misleading, leading to poor regulation or misplaced public concern.

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🧠 Implications for Critical Thinking

• Always check primary sources: This is a clear example of why it’s essential to verify claims, especially when they're used to support large-scale generalizations.

• Be skeptical of gross-ups: Scaling from small or non-representative data to national figures must be done with rigorous checks, transparency, and peer review.

• Use FOI data carefully: FOI responses, being from authoritative sources, are strong evidence — and in this case, they directly contradict the original narrative.

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🧾 Summary Judgment

The FOI response strongly suggests the original estimate of 500 deaths due to ragwort poisoning in 2000 is invalid. It exposes either a methodological failure or a misrepresentation of data, making the figure deeply unreliable and potentially misleading.

If you're investigating this further or challenging a claim, this FOI result is a powerful rebuttal.

Question 3

You said:

What can you tell me if I say that the original quote comes directly from government advice?

ChatGPT said:

If the original quote estimating 500 horse deaths from ragwort poisoning in 2000 comes directly from government advice, yet a Freedom of Information request shows only one case at the referenced hospital over eight years, then this raises serious concerns on multiple levels:

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⚖️ Implications of a Government-Originated Estimate

1. Government Credibility at Stake:

   • Government-issued advice is expected to be evidence-based, transparent, and reliable.

   • If it includes a wildly inflated estimate based on non-existent or misused data, it damages public trust in that institution and its policies.

2. Policy and Regulation Impact:

   • This estimate likely influenced ragwort control legislation, land management obligations, or public guidance to landowners.

   • Policies based on false or unsupported figures may be disproportionate, costly, or even unjustified.

3. Misuse of Authority:

   • Using an authoritative tone (e.g., citing a university hospital) to support a claim that is not factually accurate borders on misinformation, whether intentional or negligent.

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🧠 Analytical Breakdown

Let’s connect the pieces:

• Claim: 500 deaths based on extrapolated data from Liverpool University's animal hospital.

• Reality (via FOI): Only one case in eight years—not even one per year.

• Logical consequence: The core data point used to justify the extrapolation never existed.

This suggests one of the following:

• The estimation method was fabricated or misunderstood.

• The government relied on poorly vetted secondary sources.

• There was a deliberate inflation to justify a policy objective.

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🧾 Accountability Questions

This scenario invites tough questions for policymakers:

• Who created this estimate?

• Was the source peer-reviewed or independently verified?

• Why was the estimate not updated or withdrawn when more accurate data became available?

• How was the FOI data reconciled with the original policy narrative?

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💡 Broader Takeaway

This is a textbook example of why transparency, evidence verification, and skepticism are essential in interpreting government guidance — especially when it leads to regulation. It shows how bad data, once institutionalized, can cascade into widespread misinformation and skew public perception for years.

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✅ Conclusion

If a government document made this claim, yet the cited data source (the hospital) reports only one case in eight years, then the claim is:

• Demonstrably false or grossly exaggerated,

• Potentially misleading, and

• In need of correction or retraction.

It may justify a formal challenge or review of the guidance that relied on it.