The skeptic vs denier debate won’t go away. I fear the issue is far too nuanced for a broad popular consensus. But that should not prevent a consensus among science communicators, who should have a technical understanding of terminology.

A recent editorial in Forbes illustrates the problem. The author, Brian Brettschneider, makes a recommendation for when to use which term, which sounds superficially reasonable but I think he misses the essence of the issue. His solution is this – if you have an advanced degree in climate science and you have doubts about the mainstream view, then you are given the benefit of the doubt and should be referred to as a skeptic. If you do not have a formal degree in climate science, then you have no business going against the consensus of mainstream scientific opinion and you should not be given the benefit of the doubt, and are hence a denier.

This is not a bad rule of thumb as an initial assumption, but does not work as a technical distinction.

First let me say that I agree with the underlying premise. It is not a logical fallacy (argument from authority) to defer to a strong consensus of legitimate expert opinion if you yourself lack appropriate expertise. Deference should be the default position, and your best bet is to understand what that consensus is, how strong is it, and what evidence supports it. Further, if there appears to be any controversy then – who is it, exactly, who does not accept the mainstream consensus, what is their expertise, what are their criticisms, and what is the mainstream response? More importantly – how big is the minority opinion within the expert community.

This is where a bit of judgment comes in, and there is simply no way of avoiding it. There is no simple algorithm to tell you what to believe, but there are some useful rules. Obviously, the stronger the consensus, the more it is reasonable to defer to it. There is always going to be a 1-2% minority opinion on almost any scientific conclusion, that is not sufficient reason to doubt the consensus. But you also need to find out what, exactly the consensus is, and what is just a working hypothesis. Any complex theory will have multiple parts, and it’s not all a package deal.

For example, let’s take evolutionary theory. There is almost unanimous consensus (>98%) among experts that evolution happened, that all living things on Earth are related through a nestled hierarchy of common descent. Further, the evidence for that conclusion is overwhelming and cannot be reasonably denied. Further still, there is no alternative scientific hypothesis that can account for that mountain of evidence (note the word “scientific” in that sentence). But the same is not true of all aspects of evolutionary theory. That natural selection is a main driving force of evolutionary change is also well established, but there is still legitimate debate about the role and magnitude of other factors, such as genetic drift. When we drill down to details about which species evolved into which other species and when, drawing a precise tree of evolutionary relationships, then there is considerable debate and much that is unknown.

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The AP has recently published an updated version of its Stylebook, which contains the following entry:

To describe those who don’t accept climate science or dispute the world is warming from man-made forces, use climate change doubters or those who reject mainstream climate science. Avoid use of skeptics or deniers.

This debate has been going on as long as the debate about the nature of recent climate change. This is more than a nitpick, as words have real meanings and they often reflect our understanding of an issue. Those who do not accept the current consensus of climate science would prefer they be referred to as “skeptics.” This has caused a problem for the skeptical community, because the majority of scientific skeptics accept the consensus of scientific opinion on anthropogenic global warming (AGW). They feel that AGW deniers are deniers and they taint the brand of “skeptic” by adopting that term.

There is, of course, a continuum of scientific acceptance without a sharp demarcation. Following Aristotle’s golden mean, I would place proper scientific skepticism as a virtue positioned between two extremes, with denial at one end and true-belief or gullibility at the other. This scientific continuum also does not capture the entire picture, as there are those who are anti-science or who follow non-scientific philosophies.

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This Week Louisiana Governor Bobby Jindal gave an excellent lesson on how to be a science denier. Unfortunately, this was not a faux demonstration, he was sincere.

If you recall, in 2012, Jindal advised Republicans to stop being “the stupid party.” This was a provocative statement. I wondered at the time if this signaled a shift in the party away from having anti-science on their platform. Had party insiders finally realized they can’t hang their political future on denying undeniable science, that they need to embrace reality and stop fighting against it?

Alas, it seems that a more cynical interpretation is closer to the truth – that Jindal was simply worried about damage to the Republican brand caused by Republicans saying “offensive, bizarre” comments, but not by the substance of their positions on scientific issues.

At a recent breakfast hosted by the Christian Science Monitor, Jindal was introduced as a Brown graduate at the age of 20 with a biology major, then a Rhodes Scholar at Oxford, and having a 2 year stint as the president of the University of Louisiana, along with many other accomplishments. So he is a scholar and, to some extent, an academic, with advanced study in biology specifically.

During the breakfast, which included journalists, Jindal was asked about global warming. In response to this issue, Jindal performed a very deft dance. He said, “Let the scientists decide,” referring to whether or not global warming is happening. This, of course, is a clever denialist tactic. The hidden premise here is that the scientists have not already spoken with a unified and loud voice. They have decided – it is clear that human activity is increasing greenhouse gases in the atmosphere and warming the climate.

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Christine Maggiore was a major figure in the HIV denial community – those who deny that the human immunodeficiency virus is the cause of acquired immunodeficiency syndrome (AIDS). Maggiore died at 52 at home on December 26th. At this time there is no official cause of death, but she was treated over the last six months for pneumonia, according to reports.

Maggiore founded Alive & Well, a group dedicated to the notion that HIV does not cause AIDS, in 1993 and since that time has been a fervent advocate of so-called HIV denial. In fact she argued that her own survival as an untreated person with HIV was evidence that HIV does not cause AIDS. It is now recognized, however, that some people have inherent resistance to HIV and researchers are learning more about the genetics of such resistance.

Maggiore’s dedication to HIV denial, however, still had tragic consequences. She decided to breast feed both her children, despite the fact that breast feeding increases the risk of contracting the virus. Her daughter, Eliza, died at the age of 3 apparently from pneumonia that was likely an opportunistic infection due to advanced AIDS. She never had her children tested or treated for HIV.  Her pediatrician, interestingly, was anti-vaccine crank Dr. Jay Gordon. He claims to support the conclusion that HIV causes AIDS, but his website used to contain some squirely comments on HIV that suggested he may have had some denialist sympathies.

Maggiore never acknowledged that her daughter’s death was due to HIV or AIDS. The HIV denial community rallied around her, claiming the death was due to an allergic reaction to amoxicillin. Denial is a powerful thing.

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Evolution deniers (I know there is a spectrum, but generally speaking) are terrible scientists and logicians. The obvious reason is because they are committing the primary mortal sin of pseudoscience – working backwards from a desired conclusion rather than following evidence and logic wherever it leads. They therefore clasp onto arguments that are fatally flawed because they feel they can use them to support their position. One could literally write a book using bad creationist arguments to demonstrate every type of poor reasoning and pseudoscience (I should know).

A classic example is an argument mainly promoted as part of so-called “intelligent design”, which is just evolution denial desperately seeking academic respectability (and failing). The argument goes that natural selection cannot increase information, only reduce it. It does not explain the origin of complex information. For example:

A big obstacle for evolutionary belief is this: What mechanism could possibly have added all the extra information required to transform a one-celled creature progressively into pelicans, palm trees, and people? Natural selection alone can’t do it—selection involves getting rid of information. A group of creatures might become more adapted to the cold, for example, by the elimination of those which don’t carry the genetic information to make thick fur. But that doesn’t explain the origin of the information to make thick fur.

I am an educator, so I can forgive asking a naive question. Asking it in a public forum in order to defend a specific position is more dodgy, but if it were done in good faith, that could still propel public understanding forward. But evolution deniers continue to ask the same questions over and over, even after they have been definitively answered by countless experts. That demonstrates bad faith. They know the answer. They cannot respond to the answer. So they pretend it doesn’t exist, or when confronted directly, respond with the equivalent of, “Hey, look over there.”

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Have you ever been in a discussion where the person with whom you disagree dismisses your position because you got some tiny detail wrong or didn’t know the tiny detail? This is a common debating technique. For example, opponents of gun safety regulations will often use the relative ignorance of proponents regarding gun culture and technical details about guns to argue that they therefore don’t know what they are talking about and their position is invalid. But, at the same time, GMO opponents will often base their arguments on a misunderstanding of the science of genetics and genetic engineering.

Dismissing an argument because of an irrelevant detail is a form of informal logical fallacy. Someone can be mistaken about a detail while still being correct about a more general conclusion. You don’t have to understand the physics of the photoelectric effect to conclude that solar power is a useful form of green energy.

There are also some details that are not irrelevant, but may not change an ultimate conclusion. If someone thinks that industrial release of CO2 is driving climate change, but does not understand the scientific literature on climate sensitivity, that doesn’t make them wrong. But understanding climate sensitivity is important to the climate change debate, it just happens to align with what proponents of anthropogenic global warming are concluding. In this case you need to understand what climate sensitivity is, and what the science says about it, in order to understand and counter some common arguments deniers use to argue against the science of climate change.

What these few examples show is a general feature of the informal logical fallacies – they are context dependent. Just because you can frame someone’s position as a logical fallacy does not make their argument wrong (thinking this is the case is the fallacy fallacy). What logical fallacy is using details to dismissing the bigger picture? I have heard this referred to as a “Reverse Gish Gallop”. I’m don’t use this term because I don’t think it captures the essence of the fallacy. I have used the term “weaponized pedantry” before and I think that is better.

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Homer: Not a bear in sight. The Bear Patrol must be working like a charm.
Lisa: That’s specious reasoning, Dad.
Homer: Thank you, dear.
Lisa: By your logic I could claim that this rock keeps tigers away.
Homer: Oh, how does it work?
Lisa: It doesn’t work.
Homer: Uh-huh.
Lisa: It’s just a stupid rock.
Homer: Uh-huh.
Lisa: But I don’t see any tigers around, do you?
[Homer thinks of this, then pulls out some money]
Homer: Lisa, I want to buy your rock.
[Lisa refuses at first, then takes the exchange]

This memorable exchange from The Simpsons is one of the reasons the fictional character, Lisa Simpson, is a bit of a skeptical icon. From time to time on the show she does a descent job of defending science and reason, even toting a copy of “Jr. Skeptic” magazine (which was fictional at the time then created as a companion to Skeptic magazine).

What the exchange highlights is that it can be difficult to demonstrate (let alone “prove”) that a preventive measure has worked. This is because we cannot know for sure what the alternate history or counterfactual would have been. If I take a measure to prevent contracting COVID and then I don’t get COVID, did the measure work, or was I not going to get COVID anyway? Historically the time this happened on a big scale was Y2K – this was a computer glitch set to go off when the year changed to 2000. Most computer code only encoded the year as two digits, assuming the first two digits were 19, so 1995 was encoded as 95. So when the year changed to 2000, computers around the world would think it was 1900 and chaos would ensue. Between $300 billion and $500 billion were spent world wide to fix this bug by upgrading millions of lines of code to a four digit year stamp.

Did it work? Well, the predicted disasters did not happen, so from that perspective it did. But we can’t know for sure what would have happened if we did not fix the code. This has lead to speculation and even criticism about wasting all that time and money fixing a non-problem. There is good reason to think that the preventive measures worked, however.

At the other end of the spectrum, often doomsday cults, predicting that the world will end in some way on a specific date, have to deal with the day after. One strategy is to say that the faith of the group prevented doomsday (the tiger-rock strategy). They can now celebrate and start recruiting to prevent the next doomsday.

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What everyone knew was coming is now official – 2023 was the warmest year on record. This means we can also say that the last 10 years are the hottest decade on record. 2023 dethrones 2016 as the previous warmest year and bumps 2010 out of the top 10. Further, in the last half of the year, many of the months were the hottest months on record, and by a large margin. September’s average temperature was 1.44 C above pre-industrial levels, beating the previous record set in 2020 of 0.98 C. The average for 2023 is 1.4 C, beating the previous record in 2016 of 1.2 C. This also makes 2023 probably the warmest year in the last 125,000 years.

There is no mystery as to why this is happening, and it’s exactly what scientists predicted would happen. Remember the global warming “pause” that was allegedly happening between 1998 and 2012? This was the pause that never was, a short term fluctuation in the long term trend and a bit of statistical voodoo. Global warming deniers were declaring that global warming was over, it was never real, it was just a statistical fluke and the world was regressing back to the mean. Meanwhile, scientists said the long term trend had not altered and predicted the next decade would be even warmer. In retrospect, it turns out that during the alleged “pause” more heat was going into the oceans and was not fully reflected in surface temperatures.

The best test of a scientific hypothesis is its ability to make predictions about future data. The deniers were predicting that the Earth would simply return to baseline temperatures, while the scientific community were united in predicting that the next decade (now the past decade) would see continued warming.

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This is a bit of a false choice – we can do both, or neither – but it is an important question and a somewhat of a dilemma. Is the optimal path to reductions and eventual elimination of fossil fuel burning through reduced demand or supply? There are some interesting tradeoffs either way, and no perfect answer.

To focus the question, it’s clear that we need to reduce demand as quickly as possible. This is not a question, and there is no dilemma here. Reducing demand is a win-win. We can do this in a number of ways. Switching from internal combustion to battery-electric vehicles is one way. Changing coal and gas power plants to wind, solar, nuclear, hydro, and geothermal is another. Increasing energy efficiency is also important – in homes, cars, and industry. Longer term we can also shift some of our societal patterns of behavior, creating more walkable cities, expanding public transport, and reducing waste.

Basically we need to electrify our technology, switch to green energy, and maximize efficiency. All of these are good things that will reduce pollution, create jobs, foster energy independence, and improve prosperity. Even if you are a climate change denier, you should still favor the green energy revolution (don’t let political propaganda dissuade you). If we were having this conversation in the 1990s, this would be all we need to talk about. How do we accelerate the switch over from fossil fuels by investing in R&D and providing strategic tax incentives? But it’s 2023, and time is basically up.

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There are a few interesting stories lurking in this news item, but lets start with the top level – a new study revises the minimum age of the Moon to 4.46 billion years, 40 million years older than the previous estimate. That in itself is interesting, but not game-changing. It’s really a tweak, an incremental increase in precision. How scientists made this calculation, however, is more interesting.

The researchers studied zircon crystals brought back from Apollo 17. Zircon is a crystal silicate that often contains some uranium. These crystals would have formed when the magma surface of the Moon cooled. The current dominant theory is that a Mars-sized planet slammed into the proto-Earth about four and a half billion years ago, creating the Earth as we know it. The collision also threw up a tremendous amount of material, with the bulk of it coalescing into our Moon. The surface of both worlds would have been molten from the heat of the collision, but it is easier to date the Moon because the surface is better preserved. The surface of the Earth undergoes constant turnover of one type or another, while the lunar surface is ancient. So dating the Moon tells us something about the age of the Earth also.

The method of dating employed in this latest study is called atom probe tomography. First they use an ion beam microscope to carve the tip of a crystal to a sharp point. Then they use UV lasers to evaporate atoms off the tip of the crystal. These atoms pass through a mass spectrometer, which uses the time it takes to pass through as a measure of mass, which identifies the element. The researchers are interested in the proportion of uranium to lead. Uranium is a common element found in zircon, and it also undergoes radioactive decay into lead at a known rate. In any sample you can therefore use the ratio of uranium to lead to calculate the age of that sample. Doing so yielded an age of 4.46 billion years old – the new minimum age of the Moon. It’s possible the Moon could be older than this, but it can’t be any younger.

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