Theories that can be easily tested should have a high degree of consensus among researchers. Those involving chaotic and less testable questions – climate change or economic growth, physiology or financial markets – ought to have a greater level of scientific disagreement. Yet this is hardly the case for climate science. In the Paradox of Consensus, we illustrate that the greater the level of consensus for certain classes of hypotheses (those that are difficult to test) the less truth we should assign to them.
Guest Essay By D. RYAN BRUMBERG and MATTHEW BRUMBERG
The moon is not made of cheese, the earth is not flat, and lightning may strike the same place twice. We believe these claims to be true, yet it is unlikely that most readers have personally confirmed each of them. Because it would be nigh impossible for anyone to verify all they take as true, most individuals arrive at their worldview by following the beliefs of others (often “experts”). While there can be good reason to accept an idea based on its popularity, this consensus heuristic must be used with care. There must be a sufficient number of others who did arrive (and continue to arrive) at the same conclusion through independent verification and testing. When this condition is not met, the results can be catastrophic (recall the Challenger disaster). Instead of independent observers arriving at the same conclusion, we risk an information cascade. This failing goes by many names—argumentum ad populum, groupthink, the “bandwagon effect”—but its function is the same: increasing numbers of people will buy into an idea simply because many others already believe it.
Consensus, in and of itself, is not necessarily a bad thing. The more easily testable and verifiable a theory, the less debate we would expect. There is little disagreement, for example, about the sum of one plus one or the average distance of the earth from the sun. But as a question becomes more complex and less testable, we would expect an increasing level of disagreement and a lessening of the consensus—think: the existence of god, the best band since the Beatles, or the grand unified theory of physics. On such topics, independent minds can—and should—differ.
We can use a simple formula to express how an idea’s popularity correlates with its verifiability. Let us introduce the K/C ratio—the ratio of “knowability,” a broad term loosely encapsulating how possible it is to reduce uncertainty about an idea’s correctness, to “consensus,” a measure of the idea’s popularity and general acceptance. Topics that are easily knowable (K ~ 1) should have a high degree of consensus (C ~ 1), whereas those that are impossible to verify (K ~ 0) should have a low degree of consensus (C ~ 0). When the ratio deviates too far from the perfect ratio of 1, either from too much consensus or too little, there is a mispricing of knowledge. Indeed, in cases of extreme deviations from the perfect ratio, additional support for a concept with such a lopsided K/C ratio increasingly subtracts from its potential veracity. This occurs because ideas exist not simply at a single temporal point, but rather evolve over the sweep of time. At the upper reaches of consensus, there is less updating of views to account for new information—so much so that supporters of the status quo tend to suppress new facts and hypothesis. Government agencies deny funding to ‘sham’ scientists, tenure boards dissuade young researchers from pursuing ‘the wrong’ track, and the establishment quashes heretical ideas.
Consider the belief that the sun, moon, and stars circle the earth—a reasonable initial proposition. Yet, as additional facts became available (Copernicus, Brahe, Galileo), the dogmatic believers of the consensus condemned these observations as heresy. A world with a less skewed K/C ratio (lower level of consensus given low knowability) would have advanced to the heliocentric model sooner. Given that we know not the evolutionary stage for any current theory, we arrive thus at the unexpected conclusion that when knowability is low, as the level of consensus increases (without a commensurate increase in knowability), there should be a decrease in the probability assigned to the truth of the matter. While not always clear why the K/C ratio can become highly skewed, one interpretation is that more than just the search for knowledge is at play.
To see how this works in practice, we turn to the evergreen topic of climate change. Notwithstanding the underlying ecological threat of climate change itself, the debate about how to confront human-caused global warming has spawned unprecedented financial, political, and social risks of its own. Entire industries face extinction as the world’s governments seek to impose trillions of dollars of taxes on carbon emissions. The New York Times’s Thomas Friedman approvingly writes that Australian politicians—not to mention public figures through the world—now risk “political suicide” if they deny climate change. But if carbon dioxide turns out not to be the boogey-man that climate scientists have made it out to be, tens of trillions will be wasted in unneeded remediation. Much of the world—billions of humans—will endure a severely diminished quality of life with nothing to show for it. The growth trajectory of the world in the twenty-first century may well depend more on the “truth” of climate change ex ante than ex post.
With climate change, as in many areas of scientific complexity, we can (and do) use models to understand the world. But models have their problems. This is particularly true when dealing with complex, non-linear systems with a multitude of recursive feedback loops, in which small variations produce massive shifts in the long-term outcome. Pioneered by the mathematicians Edward Lorenz and Benoit Mandelbrot, chaos theory helped explain the intractability of certain problems. Readers of pop science will be familiar with the term the “butterfly effect,” in which “the flap of a butterfly’s wings in Brazil set[s] off a tornado in Texas.” The earth’s climate is one such dynamic, chaotic system and it is within the whirling, turbulent vortex of unpredictability that the modern climate scientists must tread.
And boldly have they stepped into the breach. The scope of agreement achieved by the world’s climate scientists is breathtaking. To first approximation, around 97% agree that human activity, particularly carbon dioxide emissions, causes global warming. So impressed was the Norwegian Nobel Committee by the work of the Inter-governmental Committee on Climate Change and Al Gore “for their efforts to build up and disseminate greater knowledge about man-made climate change, and to lay the foundations for the measures that are needed to counteract such change” that it awarded them the 2007 Nobel Peace Prize. So many great minds cannot possibly be wrong, right?
Yet something nags us about this self-congratulatory consensus. Our intuition is that this narrow distribution of opinions yields a knowability to consensus ratio far removed from the perfect ratio of 1. To reach their conclusions, climate scientists have to (a) uncover the (historical) drivers of climate, (b) project the future path of these inputs and others that may arise, and (c) predict how recursive feedback loops interact over multi-decadal time horizons, all without being able to test their hypotheses against reality. When evaluating the causes of past climate shifts, for example, scientists cannot simply re-run history to test the impact of changing different variables. Similarly, although climate scientists can make testable hypotheses about the future, their short-term predictions have an embarrassing record (think post-Katrina predictions of a massive surge in US hurricanes or the failed attempts to forecast temperature changes for the 2000s), while the debate will be moot by the time we can test their long-term forecasts in the year 2100.
We would, therefore, expect this limit on empirical verifiability to birth widely divergent views on the path, causes, and consequences of earth’s future climate. In other arenas, only after a theory has been empirically verified has the scientific community coalesced around it. Even then, scientists continue to subject such theories to rigorous testing and debate. For example, consider the current state of theoretical physics: quantum physics, loop quantum gravity, string theory, super-symmetry, and M-theory, among others, all vie for acceptance. Albert Einstein’s general relativity itself did not begin to garner widespread support until four years after its publication, when Arthur Eddington verified its predictions during a 1919 solar eclipse. Even so, as illustrated by the rash of headlines in late 2011 announcing the (false) discovery of faster-than-light neutrinos, scientists continue to try to poke holes in Einstein’s theory.
Yet the expectation of a rich debate among scientists about climate change does not reconcile easily with the widely endorsed shibboleth that human activity will warm the globe dramatically and dangerously over the next one hundred years. As climate scientists are themselves fond of repeating, the vast majority have arrived at the exact same conclusions about both past warming and future trends. Any discussion that doubts the fundamental premises of climate change is dismissed by the mainstream media and climate scientists as pseudo-science conducted by quacks or ideologues. Thus, questions about observational biases in the location of temperature stations, changes in the earth’s albedo, the cooling effect of dust particles, shifting ocean cycles, fluctuating solar activity, correlation v. causation of historical warm periods and carbon dioxide, catastrophic model failure caused by chaotic interactions, and innumerable other theories—most of which are presumably wrong—are never properly mooted in the public debate.
In our view, the fact that so many scientists agree so closely about the earth’s warming is, itself, evidence of a lack of evidence for global warming. Does this mean that climate change is not happening? Not necessarily. But it does mean that we should be wary of the meretricious arguments mustered in its defense. When evaluating complex questions—from climate change to economic growth, physiology to financial markets—it is worse than naïve to judge the veracity of an idea merely from the strength of consensus. The condemnation of Galileo Galilei meant one man served a sentence of life imprisonment. His ecumenical accusers at least acknowledged a force greater than science drove their decision. The modern priests of climate change endanger the lives of billions as they wield their fallacy that consensus is truth.
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According to Trenberth, it is due to ENSO, not GHG’s. [emphasis mine]
ENSO-Forced Variability of the Pacific Decadal Oscillation
MATTHEW NEWMAN, GILBERT P. COMPO, AND MICHAEL A. ALEXANDER
NOAA–CIRES Climate Diagnostics Center, University of Colorado, Boulder, Colorado
5 March 2003 and 12 June 2003
The PDO is dependent upon ENSO on all timescales.
So, it seems as though the warming is due to natural forces, not GHG’s. Nice to know Trenberth agrees.
George E.P.Box on models:
– Essentially, all models are wrong, but some are useful.
– Since all models are wrong the scientist cannot obtain a “correct” one by excessive elaboration. On the contrary following William of Occam he should seek an economical description of natural phenomena. Just as the ability to devise simple but evocative models is the signature of the great scientist so overelaboration and overparameterization is often the mark of mediocrity.
http://en.wikiquote.org/wiki/George_E._P._Box
Johann Wolfgang von Goethe, Germany’s great poet, novelist, philosopher, playwright, and scientist, wrote: “Es ist nichts schrecklicher als eine tätige Unwissenheit.” (“There is nothing more terrible than ignorance in action.”)
I would disagree, in that we are now witnessing an active ignorance driven by consensus, reminiscent of the urban legends of lemmings.
DirkH:
re your post at May 1, 2013 at 5:54 am.
A good case is spoiled by bad arguments. And a bad argument can be self-defeating for a good case.
I agree that windpower is a waste, and I agree that AGW has been used to extort from the poor to fill the pockets of the rich. But those are minor reasons for the economic problems of Spain, Portugal and Greece.
Over the last 5 years the US economy grew by the small amount of 4.8%.
Over the same period the UK economy grew by the tiny amount of 1.1%.
So, the US economy did ~5 times better than the UK economy.
Windpower and AGW do not explain the difference.
The economies of Spain, Portugal and Greece did worse than the UK economy.
Windpower and AGW do not explain the difference.
Richard
@Guest Blogger
I will be happy when, one day, religious authorities are not blamed for dictating the answers to scientific questions upon which they have no opinion.
“The condemnation of Galileo Galilei meant one man served a sentence of life imprisonment. His ecumenical accusers at least acknowledged a force greater than science drove their decision.”
His accusers were scientists, first. The Church followed the consensus.
The Ptolemaic view of an Earth-centered universe was not the creation of a church or church body but that of the ‘scientific minds’ of men in Greece. Overturning the long-held consensus that the Earth was a globe that moved around the sun, the ‘new knowledge’ dictated by Ptolemy held sway for centuries. It would be correct to call the promoters the ‘flat-earthers’. It was not the RC Church that decided on an Earth-centered universe, it was the ancient Greeks. All the church did was repeat the priestly statements of the scientists.
Today we have exactly the same thing: priestcraft by self-appointed leaders of philosophic thought. There is no need to beat around the bush. Agnostics and atheists have a long term agenda to tie anything negative they can to religion so they endlessly repeated meme that the Church of Rome was stuck-in-the-mud obstinate and refused the ‘new knowledge’ about the planets. This was only vaguely and belatedly true. All they did was ask scientists what the truth of the matter was and the scientists of the time said Ptolemy settled this long ago and that these new ideas were poppycock. If anyone bothers to investigate what happened at the time they will find that Galileo was a mouthy prat who did his best to tick off the church and succeeded. They were otherwise tolerant of multiple views of physical reality leaving such matters to the scientific community, many of whom were monks with church-sponsored laboratories. Sun-centered calculations were well known and understood by the church to be a useful method of making planetary predictions. Look it up.
While this is not the place to debate the agendas of Western materialist philosophers, it is worth the time one might spend looking into how history repeats, or rather, how we repeat, the foolish actions of our forebears as we suck up and swallow one after another consensus of the blind of eye and deaf of ear. It is not just CAGW. There are many.
Janice Moore says:
April 30, 2013 at 8:48 pm
“We are left with the impression that man is the sole cause of climate change, not one of the causes.” [Geran @1857 on 4/30/13]
Thank you, Geran……
>>>>>>>
Janice, I think you meant to address “Gofer”. He’s the one that made the comment at 6:57. I’m “Geran”, and I’m innocent of all charges….
Clovis Man,
Yep.
richardscourtney says:
May 1, 2013 at 6:07 am
“Over the last 5 years the US economy grew by the small amount of 4.8%.
Over the same period the UK economy grew by the tiny amount of 1.1%.
So, the US economy did ~5 times better than the UK economy.
Windpower and AGW do not explain the difference.”
You are sceptical about the claims of the warmists.
Why are you not sceptical about the official inflation claims of the US government?
And another thing, Richard: the GDP growth claims are not adjusted for population growth.
The population of the US grows by 1.3 % or so a year.
In that regard, the growth of the US GDP is simply abysmal.
Look at GDP/capita.
I often use this argument, but more as metaphor:
Contrast: The chemist or pilot vs the political analyst or economist.
Given a time machine, an amateur could become the greatest practitioner in the latter field – eg. subprime mortgages in 2008, FL recount in 2000. This is because you never step thru the same river twice.
In the former, even with a time machine, you would be an incompetent pilot or chemist. This is because learning in these fields comes thru experience and experimentation.
DirkH:
You made a silly mistake. Everybody does now and then.
Accept it and stop crying about it.
I said, “small amount”. You agree that. Finding similar points to whinge about is pointless and I shall ignore them if you do.
Richard
@ur momisugly Crispin
You are right about the origin of the geocentric world view; it has nothing to do with Scripture, and accordingly the curch had little difficulty to later on quietly get with the times. However, the fact remains that it was the church that suppressed free scientific inquiry.
It is not coincidence that modern science really took off only after the back of the Catholic church had been broken. Of course, the church has long since made its made its peace with science, mostly by way of surrender, and there is now little reason left on either side to pick a fight. However, look at the map of Europe, even today, and correlate advancement in science with the prevalent faith; then draw your own conclusions as to what role the church has played in history.
BTW are you in Waterloo these days? How about coffee?
This paper needs a lot of rethinking. “Knowability,” that a proposition p is true (the degree to which you can know that p) just reduces to the degree to which you are justified in believing that p (i.e., the strength of your evidence for concluding that p.) Therefore, when “knowability” is low, the “expected veracity” of p is near zero (i.e., left to luck or chance) and it simply doesn’t matter whether there is high or low consensus. The graph on the right is incorrect. It should be a line of slope zero near the bottom of the y axis.
Similarly, when the “knowability” of p is high, then the expected veracity is also high. It doesn’t matter whether the consensus is high. The graph on the left is incorrect. It should be a line of slope zero near the top of the y axis.
What you can say is that when the evidence for a proposition p is very poor and the consensus is very high, then the consensus shows that the scientists in agreement that p is true are full of baloney. You can say that. But you can’t do what this paper is trying to do. It just doesn’t come off.
You can also say that consensus is a marker for those who aren’t knowledgeable enough to understand what the evidence shows. In specific, when there is high consensus that p amongst scientists who have proven track records of tracking the truth, have carefully examined the evidence, and have high resistance to being corrupted by the lure of more funding, then I, as an ignorant layman, may be warranted in expecting that p is highly likely to be true. But when the evidence is apparently poor or the scientists have no track record to speak of, then their concensus does not warrant your expecting that p is likely to be true.
In short, this paper gets the relationship between consensus and expected veracity wrong. There is a relationship, but it is much weaker and narrower in scope than the paper says.
richardscourtney says:
May 1, 2013 at 6:50 am
“You made a silly mistake. Everybody does now and then.
Accept it and stop crying about it.
I said, “small amount”. You agree that. Finding similar points to whinge about is pointless and I shall ignore them if you do.”
So you are saying that misdirecting billions of Euros into wind turbines and solar panels is not a waste? Well, everyone is entitled to his own opinion; but while we’re at it, you can also ignore this:
During the last 5 years the Fed has generated 2 tn USD. Of course this serves to increase the nominal GDP, measured in Dollar terms of course. The fact of the matter is that the US currently generates about 10% of its GDP with the printing press, or in the words of the french economist Jacques Rueff, inflation is the creation of purchasing power in a nation with a trade deficit.
Obsessing about the alleged increase in US GDP is like calling the Zimbabwean stock market the most successful in the world, after all it went up millions of percent during the hyperinflation.
@ur momisugly Bill from Nevada
Enjoyed your posts.
There is nothing like the clarity that comes with intelligent contempt shown in scathingly humorous mockery whilst still effortlessly dealing with what is supposed to be of substance, and demonstrating it to be empty.
Not only effective, but realistic in approach to such a person, whose insinuation into discussion is bogus in its claim to sincerity, as shown by the nature of all his comments. An offence to intelligence to pretend otherwise.
To tell you something you already know, you will get nothing intelligent out of Stan W, both because of inability and disinclination. Furtive snippets then hiding is all this being is capable of.
I’m still waiting, from a previous thread, for him to state what benefits he gathers to himself, personally, from AGW being implemented as policy, and to give an estimate of how many dollars for each person dead.
Unlike many who see – rightly – that the presence of a being such as Stan W is calculated purely to confound intelligent discussion, I see it as having real virtues. The existence of such a thing, amongst many otherwise thoughtful and genuinely interested contributions, makes stark the threadbare “position” and low character of such proponents. That “Stan W” will be incapable of seeing this reinforces the point. The nature of The Beast on display.
Also, as Konrad above goes into, the record here of this entities – and others similar – contribution gives an invaluable tool to ultimately hold such things to account for their actively dishonest pursuit of goals they know have, are, and will, kill innumerable human beings.
@ur momisuglyKonrad says:
April 30, 2013 at 10:28 pm
I think your using the word “corpse” (in relation to AGW) unnerved “Stan W” somewhat. Like all his kind, being blind to killing-by-proxy is essential. God forbid that they be seen for what they are.
@ur momisuglyKonrad says:
April 30, 2013 at 11:48 pm
As with Bill from Nevada above, enjoyed your insight into the nature of “Stan W”.
@ur momisugly Konrad says:
May 1, 2013 at 5:38 am
It sounds as though you have (or are developing) a good understanding of where this has all come from and the techniques employed. In combination with others (internet!) it should be possible to establish people and links back to the genesis of this.
Like most (I suspect), I know of certain comments and claims from a handful of people at different times, and have a general cultural (political) overview, but these are not properly integrated. Probably the major task ahead, and, once this gets to the point of being untenable in a “sciency” way (not far off), this context will be all that counts, and will be the death of AGW politically and the start of accountability.
DirkH:
At May 1, 2013 at 6:07 am I wrote a post addressed to you which said
Only 92 minutes later, at May 1, 2013 at 7:39 am, you write to me
I admire your effort, and that was a good try, but you cannot outdo Stan W.
I refer you to my post at May 1, 2013 at 6:50 am.
Richard
I was a certified ‘denier’ until I read the lucid, objective and scientifically rigorous posts by the great Stan W. I have seen the error of my ways and now have an unshakeable belief in CAGW.
How could anyone not be persuaded?
Do I really need to add a sarc tag?
Barry says at 11:54 pm:
” Discuss what? The notion that scientific conclusions are more suspect if the weight of consensus is stronger?
“In our view, the fact that so many scientists agree so closely about the earth’s warming is, itself, evidence of a lack of evidence for global warming.”
The view is unlikely on its face. The implication is that scientific understanding with less consensus is more certain. The argument given, such as it is, is circular reasoning at best (more accurately, doubling down on assertions), and there is not a jot of data to back it up. ”
——————————————————————————
First of all, to Barry – thank you for making what appears to be a good-faithed attempt at argument, as that’s really all that anyone is asking for around here. There are those who do not or will not understand that.
Now to your assertion that the authors themselves assert “…that scientific conclusions are more suspect if the weight of consensus is stronger[.]”
What they assert is nothing nearly so simple, and a careful reading of the post isn’t even necessary to see this. As such, the assertion you swat down is merely the strawman you just stood up (unintentionally or not). At the core of the authors’ express argument is that:
“…as a question becomes more complex and less testable, we would expect an increasing level of disagreement and a lessening of the consensus—think: the existence of god, the best band since the Beatles, or the grand unified theory of physics. On such topics, independent minds can—and should—differ.”
They follow this by asserting (not demonstrating, obviously – just asserting) that the real-life physical complexity of the earth’s climate and of how and why it changes as it does lay on a “complexity continuum” (my term) closer to something like the field of economics than to something like the field of mathematics (my examples). Economics does not lend itself to hypotheses easily tested through experiment; therefore, it is maddeningly difficult to simplify the field. Worse, it is a field hopelessly driven in large part by politics, a driver nearly wholly antithetical to the pursuit of truth.
It’s too bad the authors didn’t use the example of economics to illustrate their point, because it is a nearly perfect illustration of it. Is it the case that there is a great deal of consensus, in general, in economics? Of course not; there is fierce and never-ending debate throughout the field, from Ph.Ds to grade-school dropouts. Were some group of economists to claim that their particular school enjoyed an overwhelming consensus of support throughout the economic world, it would be laughable. But if the private sector did not have a strong and immediate interest in economics, such that the study of it would then depend primarily on government funding around the world, there probably would eventually be manufactured a faux consensus, and the field would in many ways come to resemble climate science in its current state. (Predictably, that consensus would be some form or another of “limited government = the suffering of the masses,” would it not?)
Now, if people wish to argue that climate science is in fact MORE like math – easily tested and readily falsifiable – and LESS like economics, than by all means they should do so. Perhaps climate science truly is not very complex after all. But this is a point wholly separate from the post’s more basic one that difficult-to-test questions (if that is what they are) by their nature tend away from consensus. This point is so basic, and as a point of logic so innocuous, that I’ll be surprised to see anyone even ATTEMPT to refute it.
Perhaps that’s why the strawman was cued.
Barry,
The core theory in our paper is an application of Bayes’ theorem. The logical prior of ‘truthfulness’ one must assign to the set of questions with [ low knowability / high consensus ] IS less than the prior one must assign to the set of questions with [ low knowability / low (or medium) consensus.] For certain sets of questions, as consensus increases, the a priori analysis means the prevailing belief is LESS likely to be true. To debate this point is to misunderstand logic. I point you to http://en.wikipedia.org/wiki/Bayes'_theorem for a good primer.
There are only two ways to argue against our conclusions. 1) You can dispute anthropomorphic global warming’s knowability (admitted an non-specific term) or 2) the concomitant level of consensus. Anything else is poetry.
As an aside, I agree with anyone else who feels that the authors shoot themselves in their feet, with a shotgun, when they breezily state, “The scope of agreement achieved by the world’s climate scientists is breathtaking. To first approximation, around 97% agree that human activity, particularly carbon dioxide emissions, causes global warming.”
It doesn’t ruin their basic argument, but it sure does make you question their fundamental understanding of reality vis a vis the climate science debates. (Most people here already know why such a statement is simply goofy, in too many ways to (again!) count.) I for one will listen to you more closely if you demonstrate being in touch with reality, and less so if you do not.
IMO, the suggestion that everything stated here isn’t obvious to any college educated scientists is absurd.
So, as the consensus for CAGW drops from very high down to, say, 50%, its expected veracity will increase. And the more scientists change their minds and reject the theory, the more likely it is true, until about half of the scientific community believes it. Is that correct?
Climate change is a bit unusual because of the dynamics around what people (think they) know to be true and widely accepted. There is a segment of the population which thinks ‘the science is settled and everyone agrees’, and there is a segment which thinks ‘there is no consensus at all!’. Capturing the ways in which these dynamics interact to tease out some understanding of how much faith we should put in climate science would be interesting, but ultimately would move the paper away from its basic precept – that consensus is not truth, but it is an input into understanding the veracity of a point of view.
Yes, there is wide disagreement about climate science, but also, there is wide agreement. It depends on who you ask and where you are. If you wish to argue against global warming being primarily human caused and of dire consequences, there are a bunch of broad arguments that are typically mustered, including:
1) Climate science is not settled
2) Climate science is filled with bias
3) Warmer average temperatures might be better for people, just as they might be worse for
3) Its very expensive/impossible to alter CO2 emissions in a meaningful way.
We are merely providing an additional argument. For those who believe that the science is settled, and are unwilling to accept any other fact based perspective, there is the inescapable problem that more consensus for a low knowability idea is subtractive rather than additive to supporting their arguments – a conclusion that is (un)intuitive.
—
Provoter: We are aware that the 97% figure is badly biased, but it is also (arguably) widely believed. It is certainly bandied about in the MSM as fact. As mentioned above, it is a difficult problem to discuss climate science in general, because people’s preconceptions about what is widely accepted are vastly different. Yet this is also the value of choosing AGW to illustrate our point. Because roughly half of Americans are in fact skeptical, it is possible to use our theory to show that the consensus of the other half is not evidence of truth, without facing universal condemnation of the underlying idea simply because it is applied to a controversial topic.
Jim Ryan says:
May 1, 2013 at 11:12 am
So, as the consensus for CAGW drops from very high down to, say, 50%, its expected veracity will increase. And the more scientists change their minds and reject the theory, the more likely it is true, until about half of the scientific community believes it. Is that correct?
—
The question is what you know.
If you were to have no knowledge about the evolution of an idea, then a lower consensus for a difficult to verify topic would increase its expected veracity, because your ex-ante opinion should be that over the course of time there would be more independent verifications of the idea, and more of these verification would be recent (which is better if we assume the ability to test ideas improves over time).
In addition, lower connsensus on one idea would suggest that other ideas had gained influence, so on a meta-level, there would be more evidence that the correct idea was one of those vying for room in the debate.
In either case, we should attribute a low level of confidence to all the theories because all the theories are neither testable nor falsifiable.