It’s all relative
Do you believe in psychic powers? If not, how much evidence would you need to change your mind? Let’s say that your level of belief is so low that you think the odds that such powers exist are utterly miniscule (though crucially not zero). How much evidence would constitute proof for you? And how would that required weight of evidence differ for someone who was more amenable to the idea?
For example, let’s say that someone has performed a card-guessing experiment and found that out of 20,000 guesses the subject got the correct answer 9,410 times when, in the absence of psychic powers, the expected mean result would only be 7,420. That variance is 25 standard deviations from the mean, so you would not have expected to see such a variance by chance unless the experiment had been repeated every second since the Big Bang.
Convinced? I thought not. And yet your open-minded friend is now looking at you gobsmacked. They have seen the same evidence as you and it has confirmed everything they had expected: psychic powers are real and – congratulations, by the way – you have now become a psychic powers denier.
The example I have just provided is not hypothetical. A British mathematician and parapsychologist called Samuel Soal did indeed get those results in the 1940s when performing an experiment into psychic phenomena. So being a good Bayesian, you should have taken your prior belief in the reality of psychic phenomena and applied Bayes Rule in order to calculate a posterior level of belief that is now very high. After all, that’s only what your open-minded friend did. Admittedly, your friend started from a higher prior but, when the evidence is so strong, the level of the prior becomes somewhat immaterial. That’s Bayes for you. Ultra-strong evidence means that you don’t have to worry so much about how you chose your priors. You should be a convert and be apologising for ever having doubted your friend. So, what’s wrong with you?
Actually, the reason why you and your open-minded friend have responded so differently to the evidence is not just because of your relative prior beliefs in psychic powers, but also the relative trust you have placed in the scientific community. Either psychic powers may exist and the evidence proves it, or they don’t exist and the outcome of the experiment was due to pure chance. So, you might think there is only one pair of prior beliefs to consider here. But what about the idea that psychic powers still don’t exist and the result wasn’t pure chance but an artifact of something fishy going on? Even though fraudulent behaviour is unlikely in the general case, it is still much more likely than the existence of genuine psychic powers – at least that is how the sceptic will see it. To you as a sceptic, the results are surprising but they don’t prove the existence of psychic powers at all; they simply prove that the experimenter must be a fraud. What you would need to see, in addition to the experimental results, is proof that the figures were not fiddled. Unfortunately, no such evidence would be forthcoming in this instance because Soal had indeed been fiddling away merrily.
The climate change question
Now let’s move on. Do you believe that anthropogenic global warming poses such a threat to mankind that achieving net zero by 2050 is essential? If not, how much evidence would you need to change your mind? I presume that you are not so against the idea that you would need 25 standard deviations to overcome your scepticism. After all, the hypothesis of catastrophic anthropogenic global warming (CAGW) is not nearly as kooky as the existence of psychic powers. But the same principle exists: how you update your prior belief in the light of evidence depends crucially upon how you perceive the ratio between the likelihood of the hypothesis and the likelihood of the evidence being other than what it seems to be. You don’t have to believe in hoaxes, fiddled data or conspiracies; you just have to understand that the scientific community is not as infallible as the average Guardian or BBC journalist would have you believe. And yet, to someone who starts out with the idea of CAGW being perfectly plausible, and for someone that has developed a high degree of trust in the climate science community, the evidence that you would question will seem to them so compelling that anyone who does not fall in line with their way of thinking will be perceived as a denier rather than a sceptic.
The logic I have outlined above is very much the logic taken by hydrologist David Huard in a presentation titled ‘A Bayesian Perspective on Climate Denialism’. He appreciates that evidence offered for a Bayesian update doesn’t necessarily result in a strengthened belief, and that is because a sceptic is prepared to question the reliability of the evidence in the context of the likelihood of the hypothesis. To that extent, he and I are on the same page. However, he uses this principle to draw a distinction between true scepticism and the denier. He accuses those who dispute AGW of engaging in an ‘inferential switch’ which enables them to bolster their position irrespective of the evidence. When the evidence is against AGW, it is accepted by the sceptic and a Bayesian update lowers their strength of belief. However, when the evidence supports AGW, the sceptic suddenly invokes the hypothesis that the climate science community is ‘motivated’ and uses a low prior level of belief in the AGW hypothesis as an excuse to discredit the evidence. He refers to this as the ‘Skeptic Hijack’, and yes we really are deemed to be that shallow and transparent!
Like all arguments used against the sceptic, it can just as easily be used against those who support the orthodox view – and yet it never is. For example, I could argue that the same inferential switch is being made when the alarmist takes on board any and all evidence that supports the idea of catastrophic global warming, but then rejects counter-evidence because it is deemed to be offered by sceptics who are engaging in motivated reasoning. Huard calls the inferential switch a ‘hijack’ when a sceptic does it, but evidently it is perfectly okay to do this when defending the orthodoxy. As far as I can see, the only difference seems to be that the sceptical accusation that climate scientists can be motivated is deemed to be unfounded and unreasonable, and yet the sceptics’ own motivated reasoning is held to be well-evidenced and self-evidently problematic.
Well, they say it is well-evidenced, but it is evidenced by the likes of Naomi Oreskes, who, unfortunately, is also someone who doesn’t seem to understand the true definition of statistical significance. And frankly, it is the fact that the strongest critics of the climate sceptic can also be so ignorant of basic statistical theory that encourages me to question the evidence they themselves present. Oreskes would have you believe that I am in the thrall of Big Oil propogandists who have conned me into doubting the science, but – to be honest – I was initially quite susceptible to accepting the science uncritically until the likes of Oreskes came along and drove me into the arms of the sceptical orc army. And now I’m here, my willingness to return to the fold is hardly helped by individuals such as Huard who would selectively weaponize Bayesian logic to attack the climate sceptic’s reasoning.
Motivated reasoning or just poor reasoning?
So, what would it take to impress me? Well, first and foremost, I would prefer that the IPCC (an organisation dedicated to the idea of science by consensus) recognised that the probability of seeing something happen under a given hypothesis is not the same as the probability of a given hypothesis being true just because you see something happen. That was Oreskes’ mistake, but she’s just a historian out of her depth. The IPCC, on the other hand, is supposed to represent the finest minds on the job. And yet there is a statement in one of their technical reports to the effect that if you assumed that there was little man-made impact then there was less than a 5% chance of observing the warming that has been measured, which is then transposed in the summary for policy makers into the statement that there is at least a 95% chance that more than half the warming was man-made. This is the IPCC committing the prosecutor’s fallacy and, as such, it is a significant blow to its credibility. Which is ironic if you think about it, because here I am, a sceptic being put off by seeing supposed experts committing a classic Bayesian error, and yet Huard thinks he can use Bayesianism to demonstrate that I am pulling some sort of trick by pointing the error out.
When we are presented with new evidence we all evaluate it critically. We use evidence to update our prior beliefs, but the likelihood that we change our minds depends upon how likely we believe the evidence to be reliable, compared to how likely it is that the hypothesis being proposed is correct. When dealing with psychic powers, most of us find such a comparison easy to make. But when it comes to CAGW and the evidence proposed for it, the calculation becomes a great deal more problematic. Keep in mind that we are not just dealing with the question of whether or not mankind is contributing towards global warming; we are dealing with much more difficult questions relating to how much a contribution is being made, exactly what the impact might be, and whether the risks involved are above a threshold that can justify the damage caused by the proposed transition to net zero. In the final analysis, it’s not that needing such a transition to avoid CAGW is such a wacky idea; it’s more a case of it being too easy to believe that the evidence offered for the idea is unsound. Moreover, the more I look into how climate scientists and their advocates misapply the principles of risk management and uncertainty analysis (at least as I had come to understand them) the more difficult I find it to retain my uncritical acceptance of the warnings of doom and the resulting demands for net zero by 2050.
And whilst I am on my soap box, I might as well point out that Huard finishes his presentation by invoking the Dunning-Kruger effect, and we all know about that, don’t we boys and girls?
Climate Scepticism 
Here’s an interview of Michael Schellenberger debunking some off the lies we are told about climate change: https://www.youtube.com/watch?v=fQYIZpa3bPA.
I was struck by how cautiously optimistic he is (from ~39:00) that all of the oppressions (not just the climate change hoax) that leftist “progressives” have foist upon us in recent years are falling apart. He talks of the USA entering a new epoch. He doesn’t mention it, but that tallies with the remarkable book “The Fourth Turning” I read a few years ago which maps recurring 80-year epochs from the birth of the nation.
It might take a bit longer before any such revolution takes off on our benighted side of the pond.
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Sadly those who recognize climate doomsayers as what they are – dangerous children drawing attention to themselves – refer to those who know better as sceptics or deniers, both intentional epithets designed to demean.
Such people do not represent the genuine scientific community, but rather discredit those who do. These charlatans are not limited to climate ‘science’, but invade intellectual discourse in every sector. They attract taxpayers’ funding to perpetuate their nonsense, and those like Al Gore, happily use this malinformation in an attempt to control humanity.
Questioning is an essential scientific attribute, but these characters epitomize confirmation bias.
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Coincidentally, El Gato Malo is optimistic for the future like Shellenberger and shares his view that the Dems are now so awful that they are headed for the scrap heap: https://boriquagato.substack.com/p/upon-a-platform-of-lies.
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Repeatability.
I’m a climate crisis denier and probably a psychic powers denier. The occurrence of 25 standard deviations from the expected mean after one experiment doesn’t impress me much. The experiment should be repeated with the same ‘psychic’ subject to make sure the result wasn’t a fluke. If they can perform similarly on several occasions, then I’ll be convinced that psychic powers are real. We also need a control. Repeated experiments with random people who perform as expected if they do not possess psychic abilities. I’ll then be convinced that psychic powers are rare in human subjects.
It’s not the same with climate change on planet earth. There’s no Planet B as the hyperventilating climate activist alarmists are so fond of telling us. But, climate scientists tell us that they have detected climate change here on our one unique earth they’ve and attributed it to GHGs with near 100% certainty – because the changes detected are uniquely characteristic of GHGs and they’re unlike any other natural changes which affect the global climate. But, they can’t run the same experiment on another identical planet earth with identical cumulative GHG emissions since 1850 to check that the planet warms in the exact same way and by the exact same amount. And even more crucially, they can’t run the experiment on a counterfactual real world where there are zero industrial GHG emissions; they can only do that in cyberspace with their models. Meanwhile, evidence continues to mount that natural variability has been poorly characterised and underestimated.
So yes, I’m a ‘climate denier’ – and I’m not sure about psychic powers either.
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Cranky Irritant,
You wrote, “These charlatans are not limited to climate ‘science’, but invade intellectual discourse in every sector.” That put me in mind of the following quote from Hannah Arendt:-
“Although tyranny…may successfully rule over foreign peoples, it can stay in power only if it destroys first of all the national institutions of its own people.” ~ Hannah Arendt https://www.azquotes.com/author/511-Hannah_Arendt
The more I read of Arendt, the more I feel that she speaks very much to our current time in the West.
Regards, John C.
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Cranky Irritant,
You also wrote, “Questioning is an essential scientific attribute, but these characters epitomize confirmation bias.” To which I would add, “With their consensus science.”
By contrast, professor Feynman had a less political and altogether more robust view of science, “Science is the belief in the ignorance of experts.” ~ Richard P. Feynman https://www.azquotes.com/author/4774-Richard_P_Feynman
Feynman also said, “I would rather have questions that can’t be answered than answers that can’t be questioned.” ~ Richard P. Feynman
Perhaps I am feeling especially militant today but I think we should, with Popper (see quote below), more aggressively challenge the consensus science and insist on greater analysis of its received wisdom, and especially of its assumptions.
“If we are not prepared to defend a tolerant society against the onslaught of the intolerant, then the tolerant will be destroyed, and tolerance with them.” ~ Karl Popper https://www.azquotes.com/author/11778-Karl_Popper
Regards, John C.
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John Cullen, I love “I would rather have questions that can’t be answered than answers that can’t be questioned.” Isn’t that just the society into which we have been forced, and by those who silence opposing views?
The complete absence of even questioning, let alone debating certain claims demonstrates we’ve morphed into an intolerant society, which is completely intolerable !
Regards, CI
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Regarding the psychic powers experiment, the formulation for miracles is that it must be less likely that fraud or a mistake occurred than that an actual miracle occurred for it to be believable. In other words, the possibility of fraud or mistake has to be zero to believe the result of the psychic experiment.
The trouble with the “catastrophic” part of climate change is that there have been lots of pronouncements of imminent doom, and none have proven correct. Bayes would probably use all the failures to judge that the next prediction would fail too, rather than argue that this time the doom is real. It doesn’t help that the quality of the warnings are just embarrassingly poor, and some are even plain lies for Gaia.
See also Tony’s piece on Rode & Fischbeck, and comments below.
I’ll believe in the climate apocalypse when it happens, same as the religious version. I promise to apologise for misreading the evidence in either case, if anyone is still alive to hear me.
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There are quite a few technical gems in there, but for me, in terms of returning to the nub of the issue, this section is critical:
…Keep in mind that we are not just dealing with the question of whether or not mankind is contributing towards global warming; we are dealing with much more difficult questions relating to how much a contribution is being made, exactly what the impact might be, and whether the risks involved are above a threshold that can justify the damage caused by the proposed transition to net zero. In the final analysis, it’s not that needing such a transition to avoid CAGW is such a wacky idea; it’s more a case of it being too easy to believe that the evidence offered for the idea is unsound.…
That’s pretty much where I’m at, and I’ve been there for quite some time. And it’s very annoying that while we here at Cliscep (and others on other sceptical sites) regularly try to emphasise that these are nuanced issues, we are labelled deniers because we don’t swallow the whole kit and caboodle – namely CAGW self-evident; self-evidently catastrophic; catastrophe can be stopped by net zero; net zero in UK alone is essential regardless of what the rest of the world does; not adopting net zero in the UK will be more costly than not adopting it (regardless of what the rest of the world does); renewable energy is cheaper than fossil fuels (don’t talk about whole system costs); climate change can only cause problems, nothing good can come of it; etc etc, almost ad nauseam.
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Cranky Irritant, you raise a fascinating point when you write, “The complete absence of even questioning, let alone debating certain claims demonstrates we’ve morphed into an intolerant society …”
My parents generation fought in the Second World War, and yet they came through it, the Welfare State was created, but there was still rationing (petrol rationing in the UK ended in 1950). My parents even raised a family who grew up to go to university – an opportunity that they never had.
And the times became more liberal. The Swinging Sixities came for my generation but not my parents – I recall Germaine Greer and Kenny Everett on ‘Nice Time’ on the television. It was a time of freedom for the younger generation, but not so much for the middle aged.
It is astonishing that my generation enjoyed so much freedom at that time: freedom in clothing conventions, sexual freedom for some, freedom of thought and expression, musical freedom – I was more impressed by modern music than by my mother’s favourite, dance band leader Henry Hall.
My generation “had it all”, but we seem to have either squandered it or kept its benefits for ourselves. As an age cohort (but not necessarily as individuals) we seem meaner, more selfish, and more intolerant of non-consensus opinions than our parents generation; and yet they had the hardship while we had the fruit of their labours. We have suffered an immiseration both moral and material.
However, I suspect I am being too hard on my generation, because much of the pressure leading towards our current malaise has come from extenal influences (and their fellow travellers in the UK, especially among the political/media elites) that have in so many ways reduced the prospects for young Britons today through, for example, the imposition of Net Zero/climate change dogma/EV mandates, two-tier governance etc. etc. The standard terminology is “managed decline” but I think “deliberate accelerated decline” is a better description.
This is a fascinating topic but perhaps rather far from this thread’s ‘Rules of Credibility’. Sorry!
Regards, John C.
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As a physicist I say TY for a good commentary.
One point you missed about the IPCC. Its charter was NOT to determine if there was global warming — and if so who/what was responsible for it. Instead their original charter was to assess the human contribution to global warming. BIG difference!
FYI, I have a Substack on Critical Thinking and my latest commentary is about Climate Change <https://criticallythinking.substack.com/p/critically-thinking-about-climate>
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Wonder if the Union of Concerned Scientist are going to revise their New England’s Offshore Wind Solution, that claims “wind energy off the New England coast can powerfully reinforce the reliability of the region’s electric grid, particularly during winter when the system is most vulnerable to energy shortages.” that the Bad Boys call out as a report that lacks credibility (1)
https://energybadboys.substack.com/p/how-not-to-do-a-grid-reliability
Mark Miller
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