Climate Models Are Useless – So What?

Climate Models Are Useless – So What?

The climate debate is still in progress and a satisfying end in which all those involved reach out happily is far away. An excellent opportunity to add a little more fuel to the fire.

The very deliberately chosen title of this article may sound a little confusing at first. After all, as a veteran climate activist, one knows that the majority of scientists agree on the existence of anthropogenic climate change – even if there is uncertainty about the extent of its influence. Whereas the inclined climate sceptic tirelessly emphasizes that past predictions of doom were wrong with reliable regularity. No massive forest extinction, no islands disappearing by the dozen, and even the ozone hole seems to be closed again by about 2075.

According to this logic, it is only reasonable to be sceptical about the alarmism of Greta Thunberg and the movement Fridays for Future inspired by her. That’s not because the argument behind it is so powerful, but because we humans often don’t understand the world around us.

Evidence and Absence

The human mind has an inherent need to identify causal relationships everywhere in order to explain the world. We see the earth getting warmer and warmer since the Industrial Revolution, so it is quite clear that humankind is to blame. Or is climate only in a warm period again and the human influence is negligibly small, therefore continue as always?

None of these positions recognizes that it doesn’t really matter who is actually to blame, because any predictions based on the assumption of linear relationships are completely useless. However, before the climate skeptics triumphantly throw their arms into the air, a short detour into the philosophy of science and complex systems is necessary.

Such a system is characterized by the fact that it consists of innumerable components that may interact with each other. Among the properties of this interaction are non-linearity (B does not necessarily follow from A, proportionality is not given), adaptivity (the ability to react to changes), emergence ( new, higher-level properties that cannot be found in the individual components) and a few others that are not too important for basic understanding.

The Earth’s climate obviously belongs to the group of complex systems. However, this also poses the problem that the behaviour of such systems is impossible to predict accurately, since no model can include all components in its calculations. At this point the climate skeptic feels completely confirmed, because he always knew that one cannot trust these climate scientists and their forecasts. Without noticing it, however, he falls victim to one of the oldest problems of the search for truth: the problem of induction. As I wrote in a previous post, the idea is often attributed to the Scottish philosopher David Hume, who stated in A Treatise of Human Nature:

“There can be no demonstrative arguments to prove that those cases of which we have had no experience are similar to those of which we have had experience.”

In philosophy of science, this process is called induction. This means that, on the basis of certain premises, a possible general conclusion is derived. Note the use of the term “possible”, because the conclusion does not have to be logically compelling.

The consideration that no general laws can be derived on the basis of incomplete information is, however, already many centuries old. The Pyrrhonian skeptic Sextus Empiricus wrote about this already in the second century:

“If they intend to determine the general from the details by induction, they will do so by checking all or some of the details. But if they check some of them, the induction will be uncertain, since some of the details left out in the induction may violate the general; while if they are all to check, they will break the impossible, since the details are infinite and indeterminable.”

The most popular version of this problem is about the often mentioned black swan. If you go around the world and every swan you see is a white swan, it makes sense to conclude that all swans are white. However, a single black swan is enough to show that the general theory of white swans is not as universal as originally assumed. If these considerations are brought to a common conclusion, the following guiding principle emerges:

“The absence of evidence is not the same as evidence of absence.”

The failure of past predictions is not a reliable indicator that it must always remain so. In a complex environment, it is impossible to establish obvious causal relationships, but if more and more potential stressors are added, the risk of causing devastating events may increase.

It is dangerously naive to assume that there have always been different climate episodes in the past, and even if the situation worsens, humanity will be able to develop a new invention that prevents the worst from happening. In a complex world, it is by no means possible to make predictions based on past data. It is simply impossible to calculate rare events. A high risk aversion and thus the protection of the environment is the most rational decision. People tend to forget that in complex systems one plus one does not always equal two, but often much more. Stressors can act as super-additive functions and cause enormous damage.

Nobody knows what will happen, no model is able to predict the future.
The thing is: This is not necessary to realize that influencing systems you don’t understand can have unintended, negative consequences. By removing or at least slowing down some stressors, the risk of extreme events may be reduced. It does not require linear evidence or apocalyptic predictions to be aware of the potential damage that one’s actions could cause.

Protecting the environment is humane

Climate skeptics must be credited with the idea that correct predictions are in fact not among the things that one would cite as praiseworthy characteristics of human behaviour. However, to conclude from this that everything would somehow work out is not the answer to the problem. As climate change is a very abstract phenomenon for many people, it helps to transfer the argument just made to a more familiar event: the 2008 financial crisis.

The majority of economists did not see such a crash coming, let alone consider it possible. The mathematical models of economics at the time did not foresee such catastrophes, but of course it was by no means the first global economic crisis. It is in the nature of rare events that they cannot be predicted. The global economy is no less complex than Earth’s climate. Accordingly, forecasters also face the same problems here. Even then, there were a handful of skeptics who warned that the financial system could eventually face a huge collapse. They were right. Does this automatically mean that today’s climate skeptics are just as well on track? Perhaps. Perhaps not. Nobody knows. It would be desirable, but the risk that this is not the case can hardly be dismissed.

The public debate is facing a strange paradox:
Even if anthropogenic climate change does not exist (or does not exist to the extent to which it appears) and the world will be in perfect order as usual, where does the problem lie, at least in trying to live more sustainably? Even if one is not completely convinced of the apocalyptic narrative, there are undeniable environmental problems that adversely affect the quality of human life. The Earth itself will continue to persist. It simply exists. It does not care whether some intelligent monkeys inhabit it or not. The protection of our environment is not so much about the planet as it is about ourselves. It is something deeply humanistic.

Changing the narrative – how to talk about climate change

Changing the narrative – how to talk about climate change

Considering the renewed debate surrounding the relevance of climate change, it seems almost tragicomical that few actors are willing to allow some degree of dispassionate distance to develop strategies that are actually helpful. After all: this is possible.

In an increasingly complex world which makes it difficult for the human mind to find its way around, simple proposals for solving complicated problems become increasingly attractive. This comes as no surprise to anyone who has ever been concerned with how people perceive the world and base their decisions on this perception.

In the 1970s, psychologists Daniel Kahneman and Amos Tversky developed a theory that tries to explain how people decide in situations that involve a certain risk for themselves and for which the outcome is not obvious. In 1979, these considerations finally led to the paper “Prospect Theory: An Analysis of Decision under Risk”[1] – a work that to this day is one of the most influential in economics and which has provided the foundation for the new research field of behavioural economics.

Before Kahneman and Tversky, economic models were dominated by the view that people were always able to make rational decisions to their advantage. This kind of person is usually referred to as homo economicus. While scientific psychology at this time had long been aware that people were anything but brutally calculating, always rationally deciding actors, this insight did not yet seem to have reached the economists of that time. But the pioneering work carried out by Tversky and Kahneman and later continued by Richard Thaler, Cass Sunstein and others was soon undeniable. The credo of the always rationally deciding individual began to crumble faster and faster. Consequently, Kahneman received the Nobel Prize in Economics in 2002 and Thaler in 2017 for their research. The work on decision-making processes led to two central aspects that are important for understanding the public perception of climate change.

Less is not always more

One of these basic assumptions is described as “loss aversion” – in other words, the tendency to be more anxious to avoid losses than to make profits of comparable value. A concrete example: For the personal perception, the loss of satisfaction when losing 100€ weighs more than the gain in satisfaction when the same amount occurs as an unexpected windfall. The emotional evaluation of the loss-profit calculation therefore shows an asymmetry in favour of avoidance behaviour. Closely connected with the term loss aversion is the so-called “endowment effect”. According to this, people attribute a higher value to those things they perceive as their property than to foreign objects of similar value. Kahneman, Knetsch and Thaler (1990)[2] considered that loss aversion offers a possible explanation for the often observed endowment effect.

If one takes this idea as a starting point, it comes as little surprise that many people are repelled by the often communicated restrictions in their personal lifestyles that are demanded for the prevention of climate change. While climate change is an abstract phenomenon that is emotionally difficult to comprehend, the required renunciation of meat, air travel or children reveals itself as a concretely perceived loss of quality of life. Apparently objective projections that calculate price adjustments for many amenities – measures that are supposed to be necessary to reduce consumption and thus its impact on climate – understandably cause rejection and anger among many people. It is among the great tragedies of political ideologies that they have to work with the people they have, not those they seek.

The widespread call for more renunciation, more taxes and more restrictions will therefore only be met by those who are already willing to accept personal losses in favour of a superior idea. In many cases this is due to the fact that they do not perceive the recommended restrictions as such at all, as they already follow the proposals themselves voluntarily. However, assuming that all other people are just as willing to change their own lives is too short-sighted.

Strategies are needed that recognize that different people have diverse needs and that a “one-size-fits-all solution” will only work in the manifestos of revolutionary ideologists. Much would already have been done for public perception if there were no longer so much talk about what we must sacrifice, but what we can actively do without compromising the perceived quality of life.

In Germany, for example, one of the good news in recent history has been the idea initiated by the state of Schleswig-Holstein and the cartoonist Ralph Ruthe to plant trees or donate money for the Day of German Unity – without any coercion or scaremongering. The positive response was accordingly high. Presumably it would have looked differently if the introduction of a “tree tax” had been considered, which would be used for the same purpose, but without providing the public with a decision-making option.

The idea behind this is not new. Richard Thaler and Cass Sunstein popularized the concept of the so-called “Nudge”[3], which they also refer to as “libertarian paternalism”, with their same-named book in 2008. One of the basic assumptions is that it often makes sense to increase the number of possible options and to present certain positive alternatives in a way that makes them more obvious to the user. For example, instead of banning fast food in canteens, healthier offers are set up in a place perceived as more accessible. Every customer still has the freedom to decide whether or not to order a burger with fries on his plate, but from now on he may consider more often that a vegetarian alternative is occasionally not completely wrong. Private companies have been familiar with this type of customer influence for years and exploit it wherever possible.

The question therefore arises why political actors too often resort to fear as a motivator instead of looking for ways to provide people with more options to act or at least make them more aware of them. Because in many cases it is not so much the intensive search for a panacea as the focus on already existing possibilities that is needed. Instead of pointing out on Earth Day that the resources for the current year have theoretically been used up and that we all, once again, have to renounce, abstain, abandon, it would be much smarter in terms of communication theory to show the amount of electricity costs a private household can save through simple methods. The goal and the result are the same, but the way is completely different.

Climate change, shmimate change

Many people are annoyed with the debate about climate change. They think it’s all just a big media hysteria and Greta, Fridays for Future and others have no idea what they’re talking about. And anyway, there have always been warm and cold phases on earth.

These thoughts exist and it is important to take them seriously. A sweeping condemnation with the indication that such people are just some right-wing conservative conspiracy types after all, is not very effective.
Instead, it is worth considering the second basic assumption of behavioural economics: a dichotomy that Kahneman describes as “System 1” and “System 2”[4].

System 1 is the unconscious, intuitive mechanism that reacts quickly, automatically and emotionally and provides the basis for most everyday decisions. It would be extremely impractical for people to consciously think about every decision because life as we know it would probably be impossible. However, we should not identify System 2 as the actual decision maker. This second, logically calculating, consciously thinking system gives us the illusion that we are always master of all things and, of course, can always make rational decisions that benefit us. It is not surprising that the idea of homo economicus survived for so long. We often perceive it as our reality of life, simply because we lack knowledge of the unconscious processes that determine our own existence.

The reason why nudging can often be a useful approach to promoting desired behaviors is due to the fact that our system 1 makes many of the decisions influenceable by it. Climate change, however, which takes place as an abstract, perceived distant phenomena somewhere beyond our reality, is more accessible to the more cumbersome System 2, and only if the arguments presented are convincing and do not confront the perception of System 1 too much. Who has the time and motivation to deal with technical discussions on climate theory? This should not be understood as a criticism, but as a simple representation of the status quo as it presents itself to many people. It is completely normal that we often try to avoid stressful situations when it doesn’t seem necessary.

So should we just slap our hands above our heads, because there is no point in anything anyway and nobody really knows what he is talking about? Not quite.

Black swans and complex systems

In 2007 the statistician Nassim Nicholas Taleb published the book The Black Swan: The Impact of the Highly Improbable[5]. One of the book’s key messages is that human life and the ecosystem that surrounds it is an unbelievably complex system of countless variables that we cannot possibly all include in the assessment of the world. Hence: There is a possibility that events will occur that contradict all statistical predictions but sometimes have catastrophic consequences – the eponymous Black Swans. It is part of the irony of history that one year later an unexpected world economic crisis had very disastrous consequences in many countries – hardly anyone had expected such a far-reaching event at the time. The forecasting models used did not indicate anything. This does not mean that statistical methods are useless, quite the opposite. There are many areas in which statistical observations can be very helpful. However, it is no less important to occasionally consider the limitations of these methods and understand what can be reasonably predicted and what cannot.

According to Taleb, climate models belong in the latter category. Since it is impossible to know all relevant factors, derived forecasts based on incomplete information are also relatively worthless. Interestingly, this consideration does not lead him to the same conclusion as many critical commentators writing below the articles of numerous climate change reports.

Following his reasoning, it is absolutely necessary to be as conservative (in the literal sense of the word, meaning “preserving”) as possible with regard to environmental aspects. The possibility of a catastrophic Black Swan event exists and its effects can be so devastating that we will never recover. So even if all the models and predictions are useless (a position about which there is likely to be a good deal of controversy), it is precisely this uncertainty that makes risk-avoiding behaviour very reasonable.

One does not have to share Taleb’s rigorous rejection of statistical forecasts in complex systems to recognize the attractiveness of the argument. Sometimes it doesn’t take complicated mathematical procedures to admit that you don’t understand most things, but it may be a good idea to reduce the risk of a devastating event.

Hopefully, public discourse will shift in favour of a positive, less fear-centered debate. Instead of insisting on more and more prohibitions, restrictions and taxes, thinking about more attractive alternatives would be a very welcome change. Nobody will benefit from rejecting the major global issues of our time because we have failed to adequately illustrate their significance. Most people do not like to feel that their freedom of choice is being restricted. That is normal, that is human. We therefore need more good options, not less.


[1] Kahneman, D. & Tversky, A. (1979). “Prospect Theory: An Analysis of Decision under Risk”. Econometrica. 47 (4): 263–29

[2] Kahneman, D.; Knetsch, J.; Thaler, R. (1990). “Experimental Test of the endowment effect and the Coase Theorem”. Journal of Political Economy. 98 (6): 1325–1348.

[3] Thaler, Richard H.; Sunstein, Cass R. (2008). Nudge: Improving Decisions about Health, Wealth, and Happiness. Yale University Press

[4] Daniel Kahneman (October 25, 2011). Thinking, Fast and Slow. Macmillan.

[5] Taleb, Nassim Nicholas (2007), The Black Swan: The Impact of the Highly Improbable, Random House

The Black Swan and the Turkey

The Black Swan and the Turkey

Everything is black. Complete darkness. Tack. Tack. Tack. A faint crack. Tack. Tack. Tack. Through a tiny gap, soft sunbeams are penetrating. Tack. Tack. Tack. The gap becomes bigger, increasingly larger pieces of the former darkness disappear. Tack. Tack. Tack. Eventually the last barriers break, blocking the path to freedom, to a beautiful new world. The slightly confused gaze of a head surrounded by dishevelled feathers fights hard against the bright sunlight. Jerry? World. World? Jerry. Nice that you are there. Clumsily, Jerry stumbles away from the remains of his former home. He didn’t know what adventures the world would hold for him, but Jerry didn’t care. Whatever was coming, he was ready. The next days just flew by. There was so much to discover. He could walk across lush meadows, watch strange creatures, of which one regularly even provided him with food. A huge two-legged creature which in his mind Jerry called Hank. A very nice guy. After all, he supplied Jerry with food. Days became weeks, stretched to months and years. Jerry grew up quickly and developed a magnificent physique. Hank took great care that Jerry always had enough food and the latter took what he could get. Life was good. Jerry assumed that he had apparently been born in the best of all worlds. Where else could he have lived such a carefree life? There was nothing suggesting that this state of eternal bliss would ever change. Jerry did not feel the slightest trace of suspicion when Hank picked him up one sunny winter morning and carried him into a building Jerry had never entered before. Surely Hank just wanted to show him a new treat. Maybe more, better food? Jerry could hardly wait. He didn’t even get sceptical when Hank gently set him down on a massive wooden table, the surface of which was covered with strange furrows. Jerry watched Hank curiously and saw him taking a shiny object off the wall. Slowly Hank stepped back towards Jerry and spoke soothingly at him. He even laid Jerry on his side so he was more comfortable. Hank was just an incredibly nice guy. Life was good. Jerry saw Hank raising his hand holding the shiny object and then – nothing.
It was Christmas time and Jerry would bring a lot of joy to Hank’s family one last time that night. Life was good. For Hank.

The inductive fallacy

What lesson do we draw from Jerry and Hank’s story?
It introduces us to a central principle of scientific research logic:

“Absence of evidence is not the same as evidence of absence.”

A statistical prediction about the further trajectory of Jerry’s life based solely on his past experience and positive development would probably have assured him that everything is fine and he has a wonderful future ahead of him. Those who have read my previous article at my old blog will already be familiar with the name Nassim Nicholas Taleb and the concept of the Black Swan. Based on his argumentation in both The Black Swan[1] and Antifragile: Things That Gain from Disorder[2] is the opening story of Jerry and Hank.
In philosophy of science, this process is also called inductive reasoning. This means that, based on certain premises, a possible general conclusion is derived. Note the use of the term “possible”, because the conclusion does not have to be inevitable.
The most popular version of this problem is about the already mentioned black swan. If we go around the world and every swan we see is a white one, it is obvious that we conclude that all swans are white. However, a single black swan is enough to show us that our general theory of white swans is not as universal as we originally thought. The consideration that we cannot derive general laws on the basis of incomplete information is several centuries old. The Pyrrhonian skeptic Sextus Empiricus wrote about this as early as the second century[3]:

„When they propose to establish the universal from the particulars by means of induction, they will effect this by a review of either all or some of the particulars. But if they review some, the induction will be insecure, since some of the particulars omitted in the induction may contravene the universal; while if they are to review all, they will be toiling at the impossible, since the particulars are infinite and indefinite.”

The Scottish philosopher David Hume put it more simply in A Treatise of Human Nature a few hundred years later[4]:

„There can be no demonstrative arguments to prove, that those instances, of which we have had no experience, resemble those, of which we have had experience.”

If Jerry had enjoyed a philosophy of science education, he might have thought that his life may not be as idyllic as it seems. Not that it would have saved him, but at least he wouldn’t have left the world completely ignorant.

What is Seen and What is Unseen

I have noticed that the logic behind this idea is often overlooked. Even though we probably have more brains than turkeys. I deliberately do not say that it is difficult for people to understand it, because I think the concept is very easy to grasp. However, we quickly tend to think in linear terms. Or to put it in terms of the French philosopher Frédéric Bastiat: We focus more on what we see than what we do not see.
Bastiat illustrated this mechanism with his parable of the broken window[5]:

Have you ever witnessed the anger of the good shopkeeper, James B., when his careless son happened to break a square of glass? If you have been present at such a scene, you will most assuredly bear witness to the fact, that every one of the spectators, were there even thirty of them, by common consent apparently, offered the unfortunate owner this invariable consolation—“It is an ill wind that blows nobody good. Everybody must live, and what would become of the glaziers if panes of glass were never broken?”

Now, this form of condolence contains an entire theory, which it will be well to show up in this simple case, seeing that it is precisely the same as that which, unhappily, regulates the greater part of our economical institutions.

Suppose it cost six francs to repair the damage, and you say that the accident brings six francs to the glazier’s trade—that it encourages that trade to the amount of six francs—I grant it; I have not a word to say against it; you reason justly. The glazier comes, performs his task, receives his six francs, rubs his hands, and, in his heart, blesses the careless child. All this is that which is seen.

But if, on the other hand, you come to the conclusion, as is too often the case, that it is a good thing to break windows, that it causes money to circulate, and that the encouragement of industry in general will be the result of it, you will oblige me to call out, “Stop there! your theory is confined to that which is seen; it takes no account of that which is not seen.”

It is not seen that as our shopkeeper has spent six francs upon one thing, he cannot spend them upon another. It is not seen that if he had not had a window to replace, he would, perhaps, have replaced his old shoes, or added another book to his library. In short, he would have employed his six francs in some way, which this accident has prevented.

Neither is it possible for us to predict all (un)intended consequences, nor can we always make reliable predictions based on past experience. In principle, this phenomenon is not really problematic, provided that we are aware of its existence and its associated limitations. Both the mechanism described by Bastiat and the previously explained inductive reasoning problem are two sides of the same coin.
The uncertainty associated with this can be found in almost every area of human life and it would be easy to go into more economic and political aspects at this point. However, I would like to take this opportunity to illustrate, using a frequently used example, the consequences of equating the absence of evidence with evidence of absence.

How to see the unseen?

Anyone who has ever taken part in the discourse on anthropogenic climate change in recent years will probably be familiar with the statement that 97% of all climate scientists are convinced of the human influence on climate change. In “climate sceptical” circles it has become part of the routinely used toolkit to question this strong consensus. Even though over the years many scientists have regularly explained how this number is achieved, it seems that hardly anyone has come up with the idea of explaining the underlying logical fallacy to which the “skeptics” regularly succumb. I write very deliberately about “skeptics”, because if they were really interested in an intellectually sincere skepticism in the tradition of Sextus Empiricus, David Hume, Karl Popper and others, there would probably be far less reason for this article.
A study by Cook et al. (2013) entitled Quantifying the consensus on anthropogenic global warming in the scientific literature serves as a basis for questioning the 97% consensus. The following statement can now be found within the paper[6]:

“We analyze the evolution of the scientific consensus on anthropogenic global warming (AGW) in the peer-reviewed scientific literature, examining 11 944 climate abstracts from 1991–2011 matching the topics ‘global climate change’ or ‘global warming’.
We find that 66.4% of abstracts expressed no position on AGW, 32.6% endorsed AGW, 0.7% rejected AGW and 0.3% were uncertain about the cause of global warming.
Among abstracts expressing a position on AGW, 97.1% endorsed the consensus position that humans are causing global warming.”

Reading it for the first time, it seems quite understandable why many people are irritated when they hear that 97% of all climate scientists agree that anthropogenic climate change exists, when it is clearly stated here that only 32.6% of the literature examined has taken a confirmatory position. Subsequently, only 97.1% of these 32.6% think that humans influence the climate in a long-lasting way. Obviously, the universally praised consensus of 97% of all climate scientists is a malicious political conspiracy to lead us all into a green eco-dictatorship. If only life were always so simple.
Of course, the authors of the study are aware of this discrepancy, which is why they write at a different passage in the same (!) study:

„Of note is the large proportion of abstracts that state no position on AGW. This result is expected in consensus situations where scientists ‘…generally focus their discussions on questions that are still disputed or unanswered rather than on matters about which everyone agrees’ (Oreskes 2007, p 72). This explanation is also consistent with a description of consensus as a ‘spiral trajectory’ in which ‘initially intense contestation generates rapid settlement and induces a spiral of new questions’ (Shwed and Bearman 2010); the fundamental science of AGW is no longer controversial among the publishing science community and the remaining debate in the field has moved to other topics. This is supported by the fact that more than half of the self-rated endorsement papers did not express a position on AGW in their abstracts.”

Thus the circle closes again. Just because there is no explicit statement about something does not mean that it does not exist. The absence of evidence is not evidence of absence. In studies about evolutionary processes there is probably no explicit mention every time that evolution is a well documented fact and that the earth is not only 6000 years old. Anything else would be highly redundant.
Analogous to the findings from the data of the 2013 study, Cook et al. prepared a follow-up study that explicitly addressed the question of how deviating percentages could also be explained. Not surprisingly, they write in their summary[7]:

„Therefore, it should come as no surprise that the most common argument used in contrarian op-eds about climate change from 2007 to 2010 was that there is no scientific consensus on human-caused global warming (Elsasser and Dunlap 2012, Oreskes and Conway 2011). The generation of climate misinformation persists, with arguments against climate science increasing relative to policy arguments in publications by conservative organisations (Boussalis and Coan 2016).

Consequently, it is important that scientists communicate the overwhelming expert consensus on AGW to the public (Maibach et al 2014, Cook and Jacobs 2014). Explaining the 97% consensus has been observed to increase acceptance of climate change (Lewandowsky et al 2013, Cook and Lewandowsky 2016) with the greatest change among conservatives (Kotcher et al 2014).

From a broader perspective, it doesn’t matter if the consensus number is 90% or 100%. The level of scientific agreement on AGW is overwhelmingly high because the supporting evidence is overwhelmingly strong.“

To avoid confusion at this point, I was not just interested in showing that there is a high consensus among climate scientists about anthropogenic climate change. Above all, I would like to create an awareness that the wording of a statement does not necessarily permit a generalized derivation. We humans have a strong tendency to think in very simple categories. We observe two successive events in time and automatically believe that A necessarily causes B. However, we do not know whether this is the case. But that B can also be a consequence of causes completely unknown to us, can only be recognized if we consciously reflect about it. Unspoken statements do not always imply non-existence. Perhaps it would be time for us to show some humility in public discourse and occasionally become aware of the limits of our own knowledge.


[1] Taleb, Nassim Nicholas (2007), The Black Swan: The Impact of the Highly Improbable, Random House

[2] Taleb, Nassim Nicholas (2012), Antifragile: Things That Gain from Disorder. New York: Random House.

[3] Sextus Empiricus. Outlines of Pyrrhonism, trans. Robert Gregg Bury (Loeb ed.) (London: W. Heinemann, 1933), p. 283.

[4] Hume, David (1882). Green, T.H.; Grose, T.H. (eds.). A Treatise of Human Nature : Being an Attempt to Introduce the Experimental Method of Reasoning into Moral Subjects & Dialogues Concerning Natural Religion

[5] Bastiat, Frédéric (1850). That Which Is Seen, and That Which Is Not Seen

[6] Cook, John; Nuccitelli, Dana; Green, Sarah A.; Winkler, Bärbel; Painting, Rob; Way, Robert; Jacobs, Peter; Skuce, Andrew. Quantifying the consensus on anthropogenic global warming in the scientific literature. 2013 Environ. Res. Lett. 8. Number 2

[7] Cook, John; Oreskes, Naomi; Doran, Peter T.; Anderegg, William R. L.; Verheggen, Bart; Maibach, Ed W.; Carlton, J. Stuart; Lewandowsky, Stephan; Nuccitelli, Dana; Green, Sarah A.; Winkler, Bärbel; Painting, Rob; Jacobs, Peter; Skuce, Andrew; Rice, Ken. Consensus on consensus: a synthesis of consensus estimates on human-caused global warming. 2016 Environ. Res. Lett. 11. Number 4