Skip to main content

Are you a poor logician? Logically, you might never know

By Stephan Lewandowsky, University of Bristol and Richard Pancost, University of Bristol

This is the second article in a series, How we make decisions, which explores our decision-making processes. How well do we consider all factors involved in a decision, and what helps and what holds us back?

It is an unfortunate paradox: if you’re bad at something, you probably also lack the skills to assess your own performance. And if you don’t know much about a topic, you’re unlikely to be aware of the scope of your own ignorance.

Type in any keyword into a scientific search engine and a staggering number of published articles appears. “Climate change” yields 238,000 hits; “tobacco lung cancer” returns 14,500; and even the largely unloved “Arion ater” has earned a respectable 245 publications.

Experts are keenly aware of the vastness of the knowledge landscape in their fields. Ask any scholar and they will likely acknowledge how little they know relative to what is knowable – a realisation that may date back to Confucius.

Here is the catch: to know how much more there is to know requires knowledge to begin with. If you start without knowledge, you also do not know what you are missing out on.

This paradox gives rise to a famous result in experimental psychology known as the Dunning-Kruger effect. Named after Justin Kruger and David Dunning, it refers to a study they published in 1999. They showed that the more poorly people actually performed, the more they over-estimated their own performance.

People whose logical ability was in the bottom 12% (so that 88 out of 100 people performed better than they did) judged their own performance to be among the top third of the distribution. Conversely, the outstanding logicians who outperformed 86% of their peers judged themselves to be merely in the top quarter (roughly) of the distribution, thereby underestimating their performance.



John Cleese argues that this effect is responsible for not only Hollywood but the actions of some mainstream media.

Ignorance is associated with exaggerated confidence in one’s abilities, whereas experts are unduly tentative about their performance. This basic finding has been replicated numerous times in many different circumstances. There is very little doubt about its status as a fundamental aspect of human behaviour.

Confidence and credibility


Here is the next catch: in the eyes of others, what matters most to judge a person’s credibility is their confidence. Research into the credibility of expert witnesses has identified the expert’s projected confidence as the most important determinant in judged credibility. Nearly half of people’s judgements of credibility can be explained on the basis of how confident the expert appears — more than on the basis of any other variable.

Does this mean that the poorest-performing — and hence most over-confident — expert is believed more than the top performer whose displayed confidence may be a little more tentative? This rather discomforting possibility cannot be ruled out on the basis of existing data.

But even short of this extreme possibility, the data on confidence and expert credibility give rise to another concern. In contested arenas, such as climate change, the Dunning-Kruger effect and its flow-on consequences can distort public perceptions of the true scientific state of affairs.

To illustrate, there is an overwhelming scientific consensus that greenhouse gas emissions from our economic activities are altering the Earth’s climate. This consensus is expressed in more than 95% of the scientific literature and it is shared by a similar fraction — 97-98% – of publishing experts in the area. In the present context, it is relevant that research has found that the “relative climate expertise and scientific prominence” of the few dissenting researchers “are substantially below that of the convinced researchers”.

Guess who, then, would be expected to appear particularly confident when they are invited to expound their views on TV, owing to the media’s failure to recognise (false) balance as (actual) bias? Yes, it’s the contrarian blogger who is paired with a climate expert in “debating” climate science and who thinks that hot brick buildings contribute to global warming.

‘I’m not an expert, but…’


How should actual experts — those who publish in the peer-reviewed literature in their area of expertise — deal with the problems that arise from Dunning-Kruger, the media’s failure to recognise “balance” as bias, and the fact that the public uses projected confidence as a cue for credibility?



Speaker of the US House of Representatives John Boehner admitted earlier this year he wasn’t qualified to comment on climate change.

We suggest two steps based on research findings.
The first focuses on the fact of a pervasive scientific consensus on climate change. As one of us has shown, the public’s perception of that consensus is pivotal in determining their acceptance of the scientific facts.

When people recognise that scientists agree on the climate problem, they too accept the existence of the problem. It is for this reason that Ed Maibach and colleagues, from the Centre for Climate Change Communication at George Mason University, have recently called on climate scientists to set the record straight and inform the public that there is a scientific consensus that human-caused climate change is happening.

One might object that “setting the record straight” constitutes advocacy. We do not agree; sharing knowledge is not advocacy and, by extension, neither is sharing the strong consensus behind that knowledge. In the case of climate change, it simply informs the public of a fact that is widely misrepresented in the media.

The public has a right to know that there is a scientific consensus on climate change. How the public uses that knowledge is up to them. The line to advocacy would be crossed only if scientists articulated specific policy recommendations on the basis of that consensus.

The second step to introducing accurate scientific knowledge into public debates and decision-making pertains precisely to the boundary between scientific advice and advocacy. This is a nuanced issue, but some empirical evidence in a natural-resource management context suggests that the public wants scientists to do more than just analyse data and leave policy decisions to others.

Instead, the public wants scientists to work closely with managers and others to integrate scientific results into management decisions. This opinion appears to be equally shared by all stakeholders, from scientists to managers and interest groups.

Advocacy or understanding?


In a recent article, we wrote that “the only unequivocal tool for minimising climate change uncertainty is to decrease our greenhouse gas emissions”. Does this constitute advocacy, as portrayed by some commenters?

It is not. Our statement is analogous to arguing that “the only unequivocal tool for minimising your risk of lung cancer is to quit smoking”. Both statements are true. Both identify a link between a scientific consensus and a personal or political action.

Neither statement, however, advocates any specific response. After all, a smoker may gladly accept the risk of lung cancer if the enjoyment of tobacco outweighs the spectre of premature death — but the smoker must make an informed decision based on the scientific consensus on tobacco.

Likewise, the global public may decide to continue with business as usual, gladly accepting the risk to their children and grandchildren – but they should do so in full knowledge of the risks that arise from the existing scientific consensus on climate change.

Some scientists do advocate for specific policies, especially if their careers have evolved beyond simply conducting science and if they have taken new or additional roles in policy or leadership.
Most of us, however, carefully limit our statements to scientific evidence. In those cases, it is vital that we challenge spurious accusations of advocacy, because such claims serve to marginalise the voices of experts.

Portraying the simple sharing of scientific knowledge with the public as an act of advocacy has the pernicious effect of silencing scientists or removing their expert opinion from public debate. The consequence is that scientific evidence is lost to the public and is lost to the democratic process.
But in one specific way we are advocates. We advocate that our leaders recognise and understand the evidence.

We believe that sober policy decisions on climate change cannot be made when politicians claim that they are not scientists while also erroneously claiming that there is no scientific consensus.
We advocate that our leaders are morally obligated to make and justify their decisions in light of the best available scientific, social and economic understanding.

Click on the links below for other articles in the series, How we make decisions:
The Conversation
Stephan Lewandowsky receives funding from the Royal Society, from the World University Network (WUN), and from the 'Great Western 4' (GW4) consortium of English universities.
Richard Pancost receives funding from RCUK, the EU and the Leverhulme Trust.
This article was originally published on The Conversation. Read the original article.

Popular posts from this blog

Are you a journalist looking for climate experts? We've got you covered

We've got lots of media trained climate change experts. If you need an expert for an interview, here is a list of Caboteers you can approach. All media enquiries should be made via  Victoria Tagg , our dedicated Media and PR Manager at the University of Bristol. Email victoria.tagg@bristol.ac.uk or call +44 (0)117 428 2489. Climate change / climate emergency / climate science / climate-induced disasters Dr Eunice Lo - expert in changes in extreme weather events such as heatwaves and cold spells , and how these changes translate to negative health outcomes including illnesses and deaths. Follow on Twitter @EuniceLoClimate . Professor Daniela Schmidt - expert in the causes and effects of climate change on marine systems . Dani is also a Lead Author on the IPCC reports. Dani will be at COP26. Dr Katerina Michalides - expert in drylands, drought and desertification and helping East African rural communities to adapt to droughts and future climate change. Follow on Twitter @_k

Urban gardens are crucial food sources for pollinators - here’s what to plant for every season

A bumblebee visits a blooming honeysuckle plant. Sidorova Mariya | Shutterstock Pollinators are struggling to survive in the countryside, where flower-rich meadows, hedges and fields have been replaced by green monocultures , the result of modern industrialised farming. Yet an unlikely refuge could come in the form of city gardens. Research has shown how the havens that urban gardeners create provide plentiful nectar , the energy-rich sugar solution that pollinators harvest from flowers to keep themselves flying. In a city, flying insects like bees, butterflies and hoverflies, can flit from one garden to the next and by doing so ensure they find food whenever they need it. These urban gardens produce some 85% of the nectar found in a city. Countryside nectar supplies, by contrast, have declined by one-third in Britain since the 1930s. Our new research has found that this urban food supply for pollinators is also more diverse and continuous

#CabotNext10 Spotlight on City Futures

In conversation with Dr Katharina Burger, theme lead at the Cabot Institute for the Environment. Dr Katharina Burger Why did you choose to become a theme leader at Cabot Institute ? I applied to become a Theme Leader at Cabot, a voluntary role, to bring together scientists from different faculties to help us jointly develop proposals to address some of the major challenges facing our urban environments. My educational background is in Civil Engineering at Bristol and I am now in the School of Management, I felt that this combination would allow me to build links and communicate across different ways of thinking about socio-technical challenges and systems. In your opinion, what is one of the biggest global challenges associated with your theme? (Feel free to name others if there is more than one) The biggest challenge is to evolve environmentally sustainable, resilient, socially inclusive, safe and violence-free and economically productive cities. The following areas are part of this c