Tol/Verheggen Duke it Out with Logical Fallacies about a Logical Fallacy

Flame war: an argument between Internet users who repeatedly provoke each other with personal attacks.

flame war

I happened upon a remarkable twitter war today.  It is remarkable because it was two scientists using logical fallacies to argue about a logical fallacy.  For anyone looking for two people whose job and training it is to be reasoned and logical drop to human emotion in a political spat, this is the place to look.


I mean, wow!  Two damned good scientists arguing about a logical fallacy.  And using logical fallacies to do it.

Dramatis Personae

On one side is Bart Verheggen, a Dutch atmospheric scientist.  According to his blog, “I will try to add a voice, grounded in science, to the popular debate, to hopefully help narrowing this gap (between popular and scientific understanding).”  That’s his stated mission – to be grounded in science.  Didn’t do it this time.

On the other side is Richard Tol, a Dutch economist with a professorship in England.  Richard Tol has taken on the role of one who challenges the idea of devastating climate change.  But economists are scientists, too.  He should know better.

Needless to say, the “science” in this debate was lacking.  During the course of it it even seems as though both realized what they were doing.  But were seemingly powerless to stop it.


Briefly, a couple of years ago, there was a paper released by Cook, et al, which attempted to quantify the scientific consensus that climate change was man made.  This resulted in the popular “97 percent” number, which provides the notion that 97 percent of published research supports anthropogenic climate change.

This paper has become pretty much a cultural phenomenon.  The other side has spent a great deal of time attempting to discredit the paper, point out issues, etc.  And even going through their own review and coming to different results.

Enter Richard Tol, who sought to compare Cook’s results to the results of other reviews.  Tol attempted to show the consensus was less than the 97% figure indicated.


Logical fallacies have been identified since the days of Aristotle, who himself identified thirteen.  Logic, by its nature, requires taking a material point and providing evidence to prove that point.  Example: All cars have steering wheels.  A Corvette is a car.  Therefore, all Corvettes have steering wheels.

Another example: “CO2 absorbs and reflects longwave IR radiation. An increase in IR radiation increases the measured temperature of an atmosphere.  Therefore, an increase in CO2 increases the measured temperature of an atmosphere.”  Simple stuff.  Want to provide evidence that an increase in CO2 increases global temperatures, there you go. It’s way more complicated than that, but it’s the gist.  Put a lid on a pot of water on a stove, the water will get hotter than without a lid.  Try it yourself.  CO2 is like a lid.

Logical Fallacy

A logical fallacy occurs when something does not follow those points.  It is the introduction of something that is not relevant to the point. Example: “There is something in the sky and I don’t know what it is.  It is an unidentified flying object.  Therefore it is a ship with aliens to come and attack us.”

Another term for “logical fallacy” is “rhetoric.”  Rhetoric does not appeal to the rational mind. But it sure as hell applies to to subjective passions.  For example, let’s say a woman has five speeding tickets in the last year.  She gets cited for speeding again.  At a trial, the prosecutor wants to tell the jury that she has these tickets.  She objects and it gets sustained, because we all know that having sped before doesn’t mean she was speeding this time.  Put out the evidence that she was speeding right then.

The Cook Paper was a Logical Fallacy – Consensus Belief does not Mean Truth

There is a whole category of fallacies called “red herring” fallacies.  Historically, it was based upon training dogs to find foxes.  The trainers would attempt to lure the dogs away from the trail by placing red herrings along the way.  This would distract the hounds and they would lock onto the red herring, which was a tempting side issue. The red herring fallacies are intentional fallacies and are not dependent on language (ie a play on words or a pun).

As stated, the Cook paper sought to quantify the beliefs of scientists.  The point of the paper was that since 97% of scientists supported the concept, it is therefore true.  At least, this is how it has been marketed, even by one of the authors – Dana Nuccitelli.  The paper itself is a mixture of at least two red herring fallacies: (1) Argumentum ad populum (bandwagon); and (2) Appeal from authority.

The bandwagon fallacy is quite simple: it seeks to persuade people into a belief because the majority believe it.  It’s that simple.  “The majority of cosmologists believe in a steady state universe.” – 1940.  Just because the majority believe it does not mean it is correct.

The appeal from authority is similar. Fred Hoyle is a renowned cosmologist.  Fred Hoyle dismisses the theory of some big bang.  Therefore, you should not believe it.

We can have a mixture of these and see it quite often. The consensus of renowned cosmologists, including Einstein himself, believed in a steady state universe and George LeMaitre – some ordained priest – proposes a moment of creation.  Who is he?  You shouldn’t believe him.  All the scientists disagree and he’s pulling religion into this.

Cook et al’s paper did just this.  Took an appeal to authority (scientists) and added a bandwagon to it – 97% of scientific papers/scientists agree.  This is a logical fallacy.

Tol And Verheggen Use Logical Fallacies to Fight About a Fallacy

“The good thing about science is it’s true whether or not you believe it.”  Neil DeGrasse Tyson. From a logical and scientific standpoint, the issue of what scientists believe is beside the point.  An economist and an atmospheric scientist should both know this.  Yet they are compelled to engage in this argument.

Tol has some comments about the scientific validity and methodology behind the paper.  Yes, scientific method can be used to lend support for a fallacy.  Cook did a great job of compiling data and analyzing it.  Regardless, consensus is not evidence of truth.  Tol attacks the findings and makes the point that Verheggen himself found a low consensus in his sample size.  Because Verheggen also took a look at this data and decided to have his own take on the logical fallacy.

Then on come the responses from Verheggen.  Understandably, Verheggen wanted to correct Tol.  He knows his findings better than anyone.  But Verheggen responds not as a scientist defending his science, but as a man defending himself (which he was!):

Verheggen wrote, “That’s the outcome for outspoken contrarians.” This is a mixture of fallacies.  Guilt by association (contrarians argue this conclusion, therefore you are a contrarian) and ad hominem (contrarians are bad and therefore you are, too).  And this is just getting going.

Then Verheggen goes with appeal to authority.  https://twitter.com/BVerheggen/status/643381699590639616?ref_src=twsrc%5Etfw

These are not publishing scientists.  Therefore they should be disregarded.  This is a No True Scotsman fallacy.  They aren’t real scientists.  Then Verheggen, to his credit, catches himself and admits to being sarcastic.

Richard Tol then calls out the Verheggen’s fallacy, not quite understanding the whole debate is about a fallacy.

Verheggen takes the bait.  And comes up with Heartland (guilt by association).

Tol then goes on to a “you did it first”:

This kept on going.  It was remarkable because it was a series of fallacious statements about methodologies and results of a scientific analysis of a logical fallacy.  Really.  Look through this whole discussion/argument/flame war and find something substantive about the science of climate change.  I couldn’t find any.

There is a good reason why there was nothing about the science of climate change.  The argument is not about science.  The argument is about subjective emotion and preference.  At it’s core, the argument is about support of policy positions, and policy arguments inevitably devolve to rhetoric.

Scientists as Advocates

Scientists are people.  Just like anyone else.  They have their strong points. They have training and knowledge.  And they have (in my mind they’ve earned it) egos.  Find a surgeon without an ego.  Indeed, in many things we want people who are confident in themselves.  We don’t want a nervous surgeon.  We don’t want want pilots who are scared about flying blind.

However, advocacy is a different world.  Advocacy is not about what the science says.  Advocacy is about what the SCIENTIST feels. Science is objective.  Policy is not.

The science of climate change is true regardless of whether 100% or 97% or 3% believe it. Period.  Consensus is a creature of politics.  It is a creature of society.  That’s why bandwagon is not logic.

When scientists start advocating they lose their cloak of objectivity.  A scientist can choose to be work in obscurity and perform research, publish results, and let others decide what to do with it and remain objective n public eye.  A scientist may also be an advocate for science.  Neil DeGrasse Tyson does a pretty good job of this, his passion for science creating passion in others.

But when scientists move into policy advocacy, they are taking subjective beliefs and arguing supremacy.  Of course they are letting their human side show!  A climate scientist involved in a scrap with an economist is totally understandable.  They approach issues from different perspectives.  A patient who sees a surgeon for an issue can expect to obtain an opinion that surgery is the best option.  An internist may recommend medication or even dietary changes.  The internist and the surgeon will disagree. And it’s understood that they have different perspectives.

But this whole Tol/Verheggen scrap was high school in its approach.  They are arguing over rhetoric with more rhetoric.  They are both so much better than this.

It’s a microcosm of the whole climate debate.   Scientists cannot separate politics from the science.  The only way to proceed is for one or both sides to put on the brakes.  Just stop. Can we agree on the science?  Okay.  Can we agree on the ramifications of it?  Okay.  What are the open questions?  Let’s agree.

Does Verheggen have different priorities than Tol?  Yeah.  Does Tol value some things more than Verheggen does?  No doubt.  Do Tol and Verheggen want each other to see things their way?  No doubt.  Maybe they can agree to that.  And they can agree to disagree.

Once we can agree to disagree then we can collaborate on solutions.  And once it becomes less about personalities then it becomes more about the search for truth.

Even Larry Flynt and Jerry Falwell became friends.  Because they ended up realizing how much they had in common,  They were both just people.


10 thoughts on “Tol/Verheggen Duke it Out with Logical Fallacies about a Logical Fallacy

  1. There’s a reason why the quality and veracity of scientific papers are estimated by publishing and peer review, as opposed to Twitter and Instagram. The formats of social media restrict a full flow of information, even while improving speed of and access to messages.

    Liked by 1 person

  2. Of course. But scientists as advocates take to these platforms. In doing so their humanity comes out. This is a positive and a negative. Tol doesn’t make himself look good. And neither does Verheggen, And it makes the whole debate just look dirtier.

    Worse is that both Tol and Verheggen, and their supporters, seem to bne pumping themselves up over it.

    I haven’t lost any respect for either. I just think this is a microcosm of the climate change debate. Rationality and logic fail as the public face. Rhetoric wins out.


  3. As the lead author of the 97% consensus study, I agree with you that consensus does not necessarily decide truth. In fact, this is a point we have made since the day our paper was published in May 2013. In our Massive Open Online Course on climate science denial, I explain the crucial role of empirical evidence in this video titled “Consensus of Evidence”:

    The reason why consensus is important is because, based on a growing body of social science evidence, perceived consensus is a gateway belief. The public use the opinion of experts to guide their views on complicated scientific matters. Consequently, when the public think climate scientists disagree on human-caused global warming, they’re less likely to think climate change is happening and they’re less likely to support climate action.

    And the public *do* think there is significant scientific disagreement about climate change – when asked how many climate scientists agree that humans are causing climate change, the average answer is ~60% – a far cry from 97%.

    So the point of communicating the 97% consensus is to correct a misconception – and one of the most significant and damaging misconceptions about climate change that there is. And it is also to counter misinformation. A study of conservation opinion pieces from 2007 to 2010 found that attacking the consensus was the most common argument by those who oppose climate action.

    As for the Verheggen/Tol discussion – I suggest you may be missing the point of the discussion. Tol is comparing apples to oranges (don’t know the name of that fallacy) by comparing our 97% consensus among scientists publishing climate research to sub-samples of groups that aren’t scientific experts – and claiming that the two groups are both reflections of expert scientific consensus. Verheggen is pointing out that this is an inappropriate and misleading comparison.

    So to be clear, the reason for communicating consensus isn’t for emotional reasons – it’s a very clear-headed consideration of the social science research into the cognitive processes involved when people think about climate change. It’s about addressing the most significant and damaging misconception about climate change. This approach is based on a wide body of empirical research, which I summarise in a scholarly paper about consensus messaging at http://sks.to/ncse

    Liked by 1 person

    1. I very much like your comment. It confirms what I have said: it’s a political thing now.

      I myself believe in climate change. It’s not because somebody told me this but because I studied the issues for last decade as an autodidact and actually looking at it.

      Understanding the difference between a projection and a prediction. The science looks pretty solid on it. The projections? They aren’t designed to be testable (I did a post on that a few weeks ago).

      But the communication of the science is what is troubling. The problem faced is that to sway a public and keep the public you gotta deliver. Public supports a war in Iraq. No WMDs found? The promise wasn’t delivered. And public opinion sours.

      I think the public is pretty much in the same boat. They understand that CO2 is a greenhouse gas. But they are bombarded on all sides with reports of future cataclysm. Or by outright denial.

      I’ve often thought that the best way to sway someone isn’t to try to convince them with argument. Rather, it is to present the known facts and unknown things and let them conclude themselves.

      Indeed, the best I’ve seen at it make promises. They set the bar low. And then they deliver.

      The problem faced is that the methods for public communication of science haven’t been working. Period. The last two decades of trying to convince the public have been unsuccessful. And it’s not because the contrarians have a better grasp on the science. It’s because they keep the message simple.

      It doesn’t take Heartland Institute to say that hurricanes have been rare and relatively non destructive for the last decade. The public knows it. The 2005 and 2006 seasons were promised to be the new normal. Instead of a measured approach that said, “the oceans and atmosphere will warm, but wind shear is also supposed to increase. We don’t know what that interaction will be.”

      Boom. A dearth of hurricanes? “Wind shear appears to have a greater effect and we are still looking at it.” There is fact. No broken promises. Set expectations low. And beat them.

      This is where I see that the consensus community has blown it.

      On the other hand it is not too late. Communicate factually. Communicate what we know. Communicate the uncertainties. Let the public know, “we haven’t pinned down climate sensitivity. We cannot be sure of the sea level in 2100. We are scientists and need more data. But we can say that the earth will warm. The sea level will rise. And it won’t be uniform everywhere.”

      The. Leave it to people’s imaginations. think “Jaws.” Part of the brilliance was not seeing the shark. And let people run scenarios in their own mind.

      I hope the climate community can change their approach. It can do nothing but help the public understanding. And it will take 90 percent of the ammunition from the deniers.

      And then it leaves the science discussions as science discussions.

      Let the politicians be politicians. Let the scientists be scientists.
      Thank you for your input.


    2. Mr. Cook:

      I need help. I’m angry. What is going on with COP21 has me just furious. I’m seeing so much applause and optimism about the 1.5C limit.

      And I’m thinking, “There is not a surer way to destroy an agreement than to go harder.” I swear, I am thinking that this is a deliberate action by the US and the EU to torpedo a deal so that they can point fingers.

      Can you help me understand how a move to 1.5C actually helps get something done? Because I see nothing other than a way to make sure nothing happens.

      Same stuff. Same talk. Same tactics. Same result. Point finger.


  4. As John Cook mentioned, nobody claims that a consensus constitutes proof or truth. Since your argument rests to a great extent on that erroneous premise, much of what follows comes down to knocking down strawmen arguments.

    Besides the relevance of a consensus for public discourse, as explained by John Cook just above, it’s also a relevant gauge of scientific opinion. In our paper (http://pubs.acs.org/doi/abs/10.1021/es501998e) we wrote “As the available evidence converges over time, scientists’ aggregate opinion can be expected to reflect this convergence, resulting in a broadly -though not necessarily unanimously- shared consensus.” In other words, it’s not a coincidence and nor is it meaningless that most scientists believe that smoking increases the risk of cancer. It’s a logical results of the strength of the evidence.

    A specific example of where I think your analysis goes wrong:
    You can’t meaningfully judge scientific consensus by looking at a subsample which was constructed on the basis of their stated opinion on the issue at hand. That is a circular argument. Pointing that out has nothing to do with guilt by association or ad hominem. If you’re interested in the *scientific* consensus for the reasons stated above, it makes sense to look at the opinions of relevant *scientists*. That’s not an fallacious appeal to authority. Some interesting context regarding when something is or isn’t an appeal to authority was written by Skeptico a few years ago: http://skeptico.blogs.com/skeptico/2009/02/global-warming-denial.html

    I enjoy robust discussions about rational disagreement, but what Richard Tol claimed was something else entirely. It was so obviously wrong and frankly ridiculous that I responded with “are you joking?” Until much later in the conversation I was actually doubtful whether indeed he was being serious or not. Also keep in mind that this was twitter, not a scholarly exchange; that consensus studies and their authors have been attacked in rather weird and obnoxious ways for a long while; that scientists are people too.

    Liked by 1 person

  5. As with Mr. Cook, thank you for the comment. Very well said.

    I saw what happened. And I tried to be clear that you are human. It’s particularly worrisome when somebody says you believe something that you do not. Anybody would want to defending himself or herself in that position.

    It looked to me like something that got out of hand. And quickly. It’s the sort of thing that sours public perception. To paraphrase John Cook on it, spats like this are a gateway to public perception.

    Part of it is that lay people don’t see the scientific process. It is easy for them to see Twitter or a blog as the public face. “This is what scientists do?” It’s perception. That perception can be so easily altered. The public face of climate science is the online flame war. It’s not a perception most would want.

    And in the public mind, from a strictly anecdotal sense, strong reasons to deviate from the status quo are needed. Public perception demands that proponents of change face the burden of proof and of persuasion.

    To that extent, as I mentioned to John Cook, a change in communications methods is necessary. Example: you immediately went with the Heartland attack. One can see the effect of it by asking, “who am I persuading with this?” Nobody is being persuaded who isn’t already convinced. It gets pats on the back and approval from those who are already on you side. It confirms the divide with Heartland. The people who were on the fence? For a significant portion it merely leaves them jaded.

    I have criticisms of the deniers. I have criticisms of the alarmists. The whole debate on what to do about climate change has become each side attacking the other in public.

    Who is going to say, “enough?” Who is going to say, “I’m not going to do it that way anymore?” It’s not like a primary election in America, where to even get the chance at presidency the candidate has to appeal to his/her own constituency first. This is a chance to appeal to the other side.

    I wrote that it was worthy of you defending yourself. If you think your opinion was misrepresented then you jump in and say it. It went beyond that and became an attack of your own.

    I appreciate the comment. I really am looking to see whether there can be some type of detent in the climate change arena. It’s been nasty for a very long time. But I see so much misunderstanding of the other side on both sides.

    I wish you the best, Dr Verheggen. Again, I like that you humanized yourself by showing your feelings. We have all felt that way. It’s a matter of what is more or less constructive.

    Goodness knows I have reacted this way. And have felt the consequences of counter attacking when I could have just defended. I caused my own collateral damage.

    Liked by 1 person

  6. The author is getting all mixed up in his or her logical fallacies, introducing some red herrings into the mix. It is quite legitimate to point out that 97% of scientific papers on the subject agree that humans are causing global warming.

    I ask you. Why do you “believe” there is a thing called “gravity”? Surely it is because the science has found it so. You didn’t discover it all by yourself. You “believe” it because of the 97% of science that supports the concept of gravity.

    Similarly, why do you “believe” in evolution, or conception or that you can “catch germs” from people, or the efficacy of immunisation? These are not things that the average person discovers all by themselves. Neither are the intricacies of economics, engineering, chemistry, biology or other specialists subjects. We rely on experts in all manner of subjects.

    It is quite legitimate to argue from authority on complex subjects such as physics and climate science. When the huge majority of experts are the authority, then one can hardly dismiss their consensus as a mere “bandwagon”.

    I’d say a bit of clear thinking is required of the author.


    1. If your purpose is ideological or political, then yes. You are correct. This is why Mr. Cook pointed out that it is a tool to affect public perception, which is a fine and honest response that I appreciated.

      Policy and science get mixed in too much and it causes more confusion.

      I agree that experts arguing from authority are important. But I also don’t think that they should receive automatic deference on the basis of their title. Experts serve to provide information that forms the basis of opinion.

      Who knows more about health care? The President or Ben Carson? Yet Obama would dare to disagree with a surgeon who was so good that he was played by Cuba Gooding, Jr in a movie about him?

      Yeah. He knows about surgery. Doesn’t mean he knows much about policy. Let’s say we want a cap and trade system for carbon. Would you most want to speak to Verheggen or Tol? There is no wrong answer.

      Look at how many times you ignore expert recommendations yourself. Daily. The ones whose job it is to know most on the subject say we need the F-35. I disagree. Who am I to disagree? Just some civilian blogging about resolving conflicts. How about you? Do you have an opinion?

      So here is another question: do you believe that red wine is bad for you? What does the science say about whether or not you should drink red wine? Do scientists recommend red wine? How about doctors? Do they recommend drinking red wine? James Randi doesn’t drink. Does that make him anti-science?

      This is more along the lines of the debate. What are your thoughts on the cancer risk from secondhand smoke? If you have belief in the risk, from where did you come to that conclusion? Was it from a study of the papers? Or was it from some recommendations?

      Hint: science doesn’t recommend. Recommendations and policy all come from subjective belief. Is red wine healthy? Depends on how you define “health.” Is staving off some forms of cancer or assisting with cardiovascular efficiency worth the death of a few thousand brain cells? Would the cardio benefits of two glasses of wine be worth the DUI?

      What would the expert tell you to do? Or is the risk/benefit something that is up to you alone? I would myself suggest the latter. That you have opinions on a whole load of issues that are not based on expertise.

      Are you a logician? No. But you are commenting on this post with your own opinion. I say that’s not only fine but something I encourage it.

      Someone denies science? First thing to do is look at what that person is actually denying. Is it objective fact that is being denied? Or is it subjective interpretation that is being challenged?

      Once the “deniers” and “alarmists” start doing this, there will be a whole lot more agreement.

      Next question is: does either want that? Are you, for example, someone who would look to find ways to agree with the deniers? Or are you the type that doesn’t want to admit that maybe the deniers agree with you more than half the time?

      War is easy. Attack is easy. It’s easier to write a hatchet book on Mann than To support an argument. It’s easier to do a hatchet piece on Heartland than argue in your favor.

      It is hard to find commonality with an ideological enemy. That’s why I do what I do. Because it is hard. Some people get off on flaming each other. I get off on respect.

      Note: Verheggen and Cook actually took the time to respond and give me an idea of their thought processes. It gave me much to chew on. The human side of what they do is important to recognize. They verified that. I thank them again


  7. “Let’s say we want a cap and trade system for carbon. Would you most want to speak to Verheggen or Tol? There is no wrong answer.”

    There is no answer at all, because it’s a false choice embedded within a false question. Verheggen or Tol are not cap and trade experts, just as they do not represent the well known scientific consensus based on the overwhelming mountain of evidence in favor of AGW (with virtually none against it). The surgeon/climate scientist comparison you made is false as well. In the trauma center you don’t have 100 surgeons operating on your lungs while having 3 of them backed by the tobacco industry and libertarian interests shaking their heads saying, “nuh-uh, I wouldn’t do that.” Get real.

    I know this thread is old and you’ve probably gotten over this, but this whole thing shows you’re just dragging your feet asking a lot of irrelevant questions.

    Having said that, you’re right that facts are a lot more difficult to convey than lies on a bumper sticker, and that a poor job has been made of it, but it’s way past time to cut through your superficial outrage and get on with showing us you’re a “warmist” and not a climate science denier. We need all the help we can get to convey the AGW message while tamping down the official government consensus denial that’s just jumped up in the headlines.


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