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What might appear to be common sense is not always based on scientific evidence

The Conversation

File 20180419 163995 ztaab2.jpg?ixlib=rb 1.1
The quest for scientific evidence can trace its roots back to the classic masters of rhetoric. AboutLife/Shutterstock

James A. T. Lancaster, The University of Queensland

The term “evidence” has a fascinating linguistic and social history – and it’s a good reminder that even today the truth of scientific evidence depends on it being presented in a convincing way.

As recent climate change scepticism shows, the fortunes of scientific evidence can be swayed by something as fleeting as a tweet.


But what does it even mean to speak of “scientific evidence”?

The art of persuasion

History reveals that scientific forms of evidence have rarely, if ever, been detached from rhetoric. In fact, the very idea of evidence has its origins within the context of classical rhetoric, the art of persuasion.

Read more:
How do you know that what you know is true? That’s epistemology

Our modern term originates from the ancient Greek ἐνάργεια (enargeia), a rhetorical device whereby words were used to enhance the truth of a speech through constructing a vivid and evocative image of the things related.

Far from independent and objective, enargeia depended entirely on the abilities of the orator.

In the hands of an exceptional orator – such as the ancient Greek poet Homer – it could be deployed so effectively that listeners came to believe themselves eyewitnesses to what was being described.

Before the court

Aware of its utility to the law, the Roman statesman Marcus Tullius Cicero brought enargeia into forensic rhetoric during the 1st century BCE, translating it into Latin as evidentia.

For Roman orators such as Cicero and, in the 1st century AD, Marcus Fabius Quintilian, evidentia was particularly well suited to the courtroom.

Here it could be used to paint the scene of a grisly murder: The blood, the groans, the last breath of the dying victim. Recounting the scene of a murder in vivid language brought it immediately before the mind’s eye, affording it the quality of evidentia (“evidentness”) in the process.

Such detail was of paramount importance. The more detail the orator could furnish, the more likely it was that his account would convince the jury of its truth.

From its inception, then, enargeia/evidentia was a device that was used by one person to convince another about a particular reality that might not otherwise be evident. There was an art to it.

Scientific evidence

We can be forgiven for forgetting that the idea of scientific evidence originates in the art of rhetoric, for early modern scientists went to considerable lengths to disassociate the idea from its classical past.

Through their efforts, the meaning of evidence was shifted from a rhetorical device to denote something sufficiently self-evident that inferences could be drawn from it.

Adopting the English translation of evidentia from the common law in the 1660s, Robert Boyle (1627-1691), Robert Hooke (1635-1703) and other practitioners of the new science situated “evidence” as the end result of unbiased observation and experimentation.

Unlike classical evidentia, scientific “evidence” was objective because it spoke for itself. As the motto of the newly-minted Royal Society of Londonnullius in verba – stressed, its members were to “take no one’s word for it”.

Just like forensic evidentia, the truth of scientific evidence was based on its immediacy.

Hooke’s microscope, to give an example, permitted the viewer to witness first-hand the compound eye of the dronefly in such marvellous detail as to leave him or her without any doubt of its reality – a “see-for-yourself” mindset that was crucial to the success of science.

An illustration by Christopher Wren of the compound eye of a drone fly, contained in Robert Hooke’s book Micrographia: or Some Phyſiological Deſcriptions of Minute Bodies Made by Magnifying Glasses. With Observations and Inquiries Thereupon. British Library

Yet in practice, because most people were unable to peer through the eyepiece of a microscope, the evidence Hooke collected remained largely reliant on testimony.

Whether one accepted Hooke’s evidence for a previously unknown, microscopic world depended more on the painstakingly detailed illustrations and descriptions he gave in his 1665 Micrographia than the observations themselves.

Contrary to the Royal Society’s motto, it was not the things themselves but the way in which they were presented – and their presentation by a morally upstanding expert – that ultimately did most of the convincing.

The same holds true today. The invisible structures, processes and interactions that scientists train for years to observe remain unobservable to most people.

The temperature changes, sea level rises and acidification of the ocean that comprise some of the vast and complex evidence for climate change require, in many cases, expensive equipment, years of monitoring and specialists trained to interpret the data before climate change becomes evident.

Even when evident to scientists, this does not make climate change evidence evident to the average person.

Climate change sceptics

US president Donald Trump’s scepticism about climate change is a potent example of just how intertwined scientific evidence and rhetoric remain.

So far the Twitter Trump Archive has recorded 99 mentions of “global warming” and 32 mentions of “climate change” (both appear in some tweets) by @realDonaldTrump.

Situating his tweets as evidence against climate change, Trump poses rhetorical questions to his 50 million followers:



In marked contrast to the complex evidence for climate change, Trump positions his tweets as common sense evidence against it. In this, immediacy is on his side. Freezing weather is readily apparent to everyone, not just to scientists.

Trump’s followers are made direct witnesses to the truth of climate change by appeal to that which is most evident to them and thus, by implication, that which is the best evidence.

Even if a record cold and snow spell is not, in reality, evidence against climate change, its capacity to convince is greater because, unlike genuine evidence for climate change, it is both simple and immediate.

Read more:
Science isn’t broken, but we can do better: here’s how

Evidence for climate change, on the other hand, requires trust in the scientific community, a trust that is meant to offset its lack of immediacy and which asks us to suspend our senses.

Trump’s tweets aim to delegitimise this trust, empowering his followers by telling them to trust the evidence of their own senses, their own expertise.

As scientific evidence has become increasingly complex, so too has the idea of “clear scientific evidence” become an oxymoron. If anything, Trump’s assault on climate change should serve as a reminder that making scientific evidence evident enough to convince the public is an art that needs to be embraced.

The ConversationScientific evidence can’t always be expected to speak for itself.

James A. T. Lancaster, UQ Research Fellow, The University of Queensland

This article was originally published on The Conversation. (Reblogged by permission). Read the original article.

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We can’t trust common sense but we can trust science

The Conversation

Peter Ellerton, The University of Queensland

When a group of Australians was asked why they believed climate change was not happening, about one in three (36.5%) said it was “common sense”, according to a report published last year by the CSIRO. This was the most popular reason for their opinion, with only 11.3% saying their belief that climate change was not happening was based on scientific research.

Interestingly, the same study found one in four (25.5%) cited “common sense” for their belief that climate change was happening, but was natural. And nearly one in five (18.9%) said it was “common sense” that climate change was happening and it was human-induced.

It seems the greater the rejection of climate science, the greater the reliance on common sense as a guiding principle.

Former prime minister Tony Abbott also appealed to “common sense” when arguing against gay marriage recently.

But what do we mean by an appeal to common sense? Presumably it’s an appeal to rationality of some sort, perhaps a rationality that forms the basis of more complex reasoning. Whatever it is, we might understand it better by considering a few things about our psychology.

It’s only rational

It’s an interesting phenomenon that no one laments his or her lack of rationality. We might complain of having a poor memory, or of being no good at maths, but no one thinks they are irrational.

Worse than this, we all think we’re the exemplar of the rational person (go on, admit it) and, if only everyone could see the world as clearly as we do, then all would be well.

Rather than being thought of as the type of reasoning everyone would converge on after thoughtful reflection, however, common sense too often just means the kind of sense we individually have. And anyone who agrees with us must also, logically, have it.

But more likely, as Albert Einstein supposedly put it:

[…] common sense is actually nothing more than a deposit of prejudices laid down in the mind prior to the age of eighteen.

In other words, common sense is indeed very common, it’s just that we all have a different idea of what it is.

Thinking that feels right

The appeal to common sense, therefore, is usually nothing more than an appeal to thinking that just feels right. But what feels right to one person may not feel right to another.

When we say to each other “that sounds right”, or “I like the sound of that”, we are generally not testing someone’s argument for validity and soundness as much as seeing if we simply like their conclusion.

Whether it feels right is usually a reflection of the world view and ideologies we have internalised, and that frame how we interact with new ideas. When new ideas are in accord with what we already believe, they are more readily accepted. When they are not, they, and the arguments that lead to them, are more readily rejected.

We too often mistake this automatic compatibility testing of new ideas with existing beliefs as an application of common sense. But, in reality, it is more about judging than thinking.

As the psychologist and Nobel Laureate Daniel Kahneman notes in his book Thinking Fast and Slow, when we arrive at conclusions in this way, the outcomes also feel true, regardless of whether they are. We are not psychologically well equipped to judge our own thinking.

We are also highly susceptible to a range of cognitive biases, such as the availability heuristic that preference the first things that come to mind when making decisions or giving weight to evidence.

One way we can check our internal biases and inconsistencies is through the social verification of knowledge, in which we test our ideas in a rigorous and systematic way to see if they make sense not just to us, but to other people. The outstanding example of this socially shared cognition is science.

Social cognition can be powerful.
Pixabay, CC BY

Science is not common sense

It’s important to realise that science is not about common sense. Nowhere is this more evident than in the worlds of quantum mechanics and relativity, in which our common sense intuitions are hopelessly inadequate to deal with quantum unpredictability and space-time distortions.

But our common sense fails us even in more familiar territory. For centuries, it seemed to people that the Earth could not possibly be moving, and must therefore be at the centre of the universe.

Many students still assume that an object in motion through space must have a constant force acting on it, an idea that contradicts Newton’s first law. Some people think that the Earth has gravity because it spins.

And, to return to my opening comment, some people think that their common sense applied to observations of the weather carries more weight on climate change than the entire body of scientific evidence on the subject.

Science is not the embodiment of individual common sense, it is the exemplar of rational collaboration. These are very different things.

It is not that individual scientists are immune from the cognitive biases and tendencies to fool themselves that we are all subject to. It is rather that the process of science produces the checks and balances that prevent these individual flaws from flourishing as they do in some other areas of human activity.

In science, the highest unit of cognition is not the individual, it is the community of scientific enquiry.

Thinking well is a social skill

That does not mean that individuals are not capable of excellent thinking, nor does it mean no individual is rational. But the extent to which individuals can do this on their own is a function of how well integrated they are with communities of systematic inquiry in the first place. You can’t learn to think well by yourself.

In matters of science at least, those who value their common sense over methodological, collaborative investigation imagine themselves to be more free in their thinking, unbound by involvement with the group, but in reality they are tightly bound by their capabilities and perspectives.

We are smarter together than we are individually, and perhaps that’s just common sense.

Peter Ellerton will be online today, Tuesday February 2, 2016, to answer your questions or comments on common sense. Here are the times for Australia’s states and territories:

  • 2pm and 3pm (Qld)
  • 3pm to 4pm (NSW, Tas, Vic and ACT)
  • 2.30pm to 3.30pm (SA)
  • 1.30pm to 2.30pm (NT)
  • Noon to 1pm (WA)

The ConversationPeter Ellerton, Lecturer in Critical Thinking, The University of Queensland

This article was originally published on The Conversation. (Reblogged by permission). Read the original article.

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Why would anyone believe the Earth is flat?

The Conversation

Peter Ellerton, The University of Queensland

Belief in a flat Earth seems a bit like the attempt to eradicate polio – just when you think it’s gone, a pocket of resistance appears. But the “flat Earthers” have always been with us; it’s just that they usually operate under the radar of public awareness.

Now the rapper B.o.B has given the idea prominence through his tweets and the release of his single Flatline, in which he not only says the Earth is flat, but mixes in a slew of other weird and wonderful ideas.

These include the notions that the world is controlled by lizard people, that certain celebrities are cloned, that Freemasons manipulate our lives, that the sun revolves around the Earth and that the Illuminati control the new world order. Not bad for one song.

Even ignoring that these ideas are inconsistent (are we run by lizards, the Freemansons or the Illuminati?), what would inspire such a plethora of delusions? The answer is both straightforward, in that it is reasonably clear in psychological terms, and problematic, in that it can be hard to fix.

Making our own narratives

Humans are, above all things, story-telling animals. It is impossible to live our lives without constructing narratives. I could not present a word pair such as (cage, bird) without you joining them in a narrative or image. Same with (guitar, hand) or (river, bridge). Even when we read seemingly unrelated word pairs such as (pensioner, wardrobe), our brains actively try to match the two (and you’re still doing it).

The stories that define us as a culture, a group or as a species are often complex and multifaceted. They speak of many things, including creation, nature, community and progress.

We create stories for two reasons. The first is to provide explanatory power, to make causal sense of the world around us and help navigate through the landscapes of our lives. The second reason is to give us meaning and purpose.

Not only do we understand our world through stories, we understand our place in it. The stories can be religious, cultural or scientific, but serve the same purpose.

Our stories make sense of the world.
The Elders/flickr

Scientific narratives

In science, our stories are developed over time and build on the work of others. The narrative of evolution, for example, provides breathtaking explanatory power. Without it, the world is simply a kaleidoscope of form and colour. With it, each organism has function and purpose.

As the Ukrainian-American geneticist and evolutionist Theodosius Dobzhansky said in his famous essay:

Nothing in biology makes sense except in the light of evolution.

Through evolution, we have developed an understanding of how we fit into the scheme of life, and the vast and deep history of our planet. For many of us, this knowledge provides meaning and an appreciation of the fact of our existence.

Similarly, the story of our solar system’s formation is rich and compelling, and includes the explanation for why the Earth is, in fact, more or less spherical.

So why would someone reject all this?

One reason might be that accepting mainstream scientific findings necessitates rejecting an existing narrative. Such is the case for evolution within fundamentalist interpretations of the Bible.

For the literally religious, accepting evolution necessitates rejecting their world view. It is not about weighing scientific evidence, it is about maintaining the coherence and integrity of their narrative. The desperate and unsuccessful search for evidence to contradict evolution by young Earth creationists is a manifestation of this attempt at ideological purification.

Another reason to reject scientific narratives is that we feel we do not have meaning within them, or we do not belong to the community that created them.

As I’ve said elsewhere concerning conspiracy theories, in a world in which there is so much knowledge, and in which we individually hold so little of it, it is sometimes difficult to see ourselves as significant.

What’s more, science, it turns out, is hard. So if we want to own this narrative, it might take a bit of work.

Freedom from rationality

It is therefore tempting to find a way of thinking about the world that both dismisses the necessity of coming to grips with science, and restores us to a privileged social position.

Rejecting science and embracing an alternative view, such as the Earth being flat, moves the individual from the periphery of knowledge and understanding to a privileged position among those who know the “truth”.

In BoB’s lyrics, he calls himself “free thinking”. In this phrasing we see a glimpse of the warrant he gives himself to reject science, considering it a “cult”.

He appeals instead to his common sense to establish that the Earth must be flat. The appeal to common sense is a characteristic way of claiming to be rational while denying the collective rationality of the scientific community (and a typical argument in climate denial).

It’s also about recapturing a feeling of independence and control. We know from research that there is a correlation between feeling a lack of control in your life and belief in conspiracy theories.

If we can rise above the tide of mainstream thinking and find a place from which we can hold a unique and controversial view, we might hope to be more significant and find a purpose to which we can lend our talents.

Coming back from the edge

So how could we engage someone with such beliefs, with view to changing their minds? That’s no easy task, but two things are important.

The first is to have both the facts and their means of verification at hand – after all, you need something to point to. Sometimes, if the narrative is weak or in tension, that might do the job.

The second thing, because facts are often not enough, is to understand the style and depth of the narrative an individual has developed, and the reasons it’s developed as it has. It’s only from that point that progress can be made against otherwise intractable opposition to collective wisdom.

But why bother? Why not let rappers rap, preachers preach and deniers deny? It might seem that we are just dealing with a fringe on the edge of the rational (or literal) world. But, of course, in the case of things such as vaccination and climate change, the consequences of inaction against these views are potentially damaging.

Either way, we should at least stand up for knowledge that has been hard won through collective endeavours over generations and individual lives dedicated to its pursuit.

Because if all views are equal then all views are worthless, and that’s something none of us should accept.

The ConversationPeter Ellerton, Lecturer in Critical Thinking, The University of Queensland

This article was originally published on The Conversation. (Reblogged by permission). Read the original article.


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Infections of the mind: why anti-vaxxers just ‘know’ they’re right

The Conversation

Thom Scott-Phillips, Durham University

Anti-vaccination beliefs can cause real, substantive harm, as shown by the recent outbreak of measles in the US. These developments are as shocking and distressing as their consequences are predictable. But if the consequences are so predictable, why do the beliefs persist?

It is not simply that anti-vaxxers don’t understand how vaccines work (some of them may not, but not all of them). Neither are anti-vaxxers simply resistant to all of modern medicine (I’m sure that many of them still take pain killers when they need to). So the matter is not as simple as plain stupidity. Some anti-vaxxers are not that stupid, and some stupid people are not anti-vaxxers. There is something more subtle going on.

Naïve theories

We all have what psychologists call “folk” theories, or “naïve” theories, of how the world works. You do not need to learn Newton’s laws to believe that an object will fall to the floor if there is nothing to support it. This is just something you “know” by virtue of being human. It is part of our naïve physics, and it gives us good predictions of what will happen to medium-sized objects on planet earth.

Naïve physics is not such a good guide outside of this environment. Academic physics, which deals with very large and very small objects, and with the universe beyond our own planet, often produces findings that are an affront to common sense.

A life force. Food by Shutterstock

As well as physics, we also have naïve theories about the natural world (naïve biology) and the social world (naïve psychology). An example of naïve biology is “vitalistic causality” – the intuitive belief that a vital power or life force, acquired from food and water, is what makes humans active, prevents them from being taken ill, and enables them to grow. Children have this belief from a very young age.

Naïve theories of all kinds tend to persist even in the face of contradictory arguments and evidence. Interestingly, they persist even in the minds of those who, at a more reflexive level of understanding, know them to be false.

In one study, adults were asked to determine, as quickly as possible, whether a statement was scientifically true or false. These statements were either scientifically true and naïvely true (“A moving bullet loses speed”), scientifically true but naïvely false (“A moving bullet loses height”), scientifically false but naïvely true (“A moving bullet loses force”), or scientifically false and naïvely false (“A moving bullet loses weight”).

Adults with a high degree of science education got the questions right, but were significantly slower to answer when the naïve theory contradicted their scientific understanding. Scientific understanding does not replace naïve theories, it just suppresses them.

Sticky ideas

As ideas spread through a population, some stick and become common, while others do not. The science of how and why ideas spread through populations is called cultural epidemiology. More and more results in this area are showing how naïve theories play a major role in making some ideas stickier than others. Just as we have a natural biological vulnerability to some bacteria and not others, we have a natural psychological vulnerability to some ideas and not others. Some beliefs, good and bad, are just plain infectious.

Here is an example. Bloodletting persisted in the West for centuries, even though it was more often than not harmful to the patient. A recent survey of the ethnographic data showed that bloodletting has been practiced in one form or another in many unrelated cultures, across the whole world.

Paraphernalia. (Source: Peter Merholz, CC BY-SA)

A follow-up experiment showed how stories that do not originally have any mention of bloodletting (for instance, about an accidental cut) can, when repeated over and over again, become stories about bloodletting, even among individuals with no cultural experience of bloodletting.

These results cannot be explained by bloodletting’s medical efficiency (since it is harmful), or by the perceived prestige of western physicians (since many of the populations surveyed had no exposure to them). Instead, the cultural success of bloodletting is due to the fact that it chimes with our naïve biology, and in particular with our intuitive ideas of vitalistic causality.

Bloodletting is a natural response to a naïve belief that the individual’s life force has been polluted in some way, and that this pollution must be removed. Anti-vaccination beliefs are a natural complement to this: vaccinations are a potential poison that must be kept from the body at all costs.

At an intuitive, naïve level we can all identify with these beliefs. That is why they can satirised in mainstream entertainment.

In Stanley Kubrick’s great comedy Dr. Strangelove, the American general Jack D. Ripper explains to Lionel Mandrake, a group captain in the Royal Air Force, that he only drinks “distilled water, or rainwater, and only pure grain alcohol”, because, he believes, tap water is being deliberately infected by Communists to “sap and impurify all of our precious bodily fluids”. The joke works because Ripper’s paranoia is directed at something we all recognise: the need to keep our bodies free from harmful, alien substances. Anti-vaxxers think they are doing the same.

The ConversationThis article was originally published on The Conversation. (Reblogged by permission). Read the original article.

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Common sense fallacy

by Tim Harding

The American writer H L Mencken once said “There is always a well-known solution to every human problem — neat, plausible, and wrong.” He was referring to ‘common sense’, which can be superficially plausible and sometimes right, but often wrong.

The Common Sense Fallacy (or ‘Appeal to Common Sense’) is superficially similar to the Argument from Popularity and/or  the Argument from Tradition. However, it differs from these fallacies by not necessarily relying on popularity or tradition.

Instead, common sense relies on the vague notion of ‘obviousness’, which means something like ‘what we perceive from personal experience’ or ‘what we should know without having had to learn.’ In other words, common sense is not necessarily supported by evidence or reasoning. As such, beliefs based on common sense are unreliable.  The fallacy lies in giving too much weight to common sense in drawing conclusions, at the expense of evidence and reasoning.

In some ways, scientific methods have been developed to avoid the errors that can result from common sense. For instance, common sense used to tell us that the Earth is flat and that the Sun revolves around the Earth – because that is the way things appear to us without scientific investigation.  Another example of ‘common sense’ is that the world appears to have been designed, so therefore there must have been a designer.

Einstein’s theories of relativity were initially resisted, even by the scientific community, because they defied common sense.  They seemed to belong more in the realm of science fiction than reality, until they were later verified by scientific observations.  Our modern Global Positioning System (GPS) now uses Einstein’s relativity theories.  This initial resistance may have led Einstein to later say that ”Common sense is nothing more than a deposit of prejudices laid down by the mind before you reach eighteen” .

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