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A Brain Designed to Win Arguments – Not Think Factually?

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confirmation bias – the mind’s tendency to pick and choose information to support our preconceptions, while ignoring a wealth of evidence to the contrary.

The confirmation bias is just one of a truckload of flaws in our thinking that psychologists have steadily documented over the past few decades. Indeed, everything from your choice of cellphone to your political agenda is probably clouded by several kinds of fuzzy logic that sway the way you weigh up evidence and come to a decision.

Hugo Mercier at the University of Neuchâtel, Switzerland, and Dan Sperber at the Central European University in Budapest, Hungary, believe that human reasoning evolved to help us to argue.

An ability to argue convincingly would have been in our ancestors’ interest as they evolved more advanced forms of communication, the researchers proposeSince the most persuasive lines of reasoning are not always the most logical, our brains’ apparent foibles may result from this need to justify our actions and convince others to see our point of view – whether it is right or wrong.

“You end up making decisions that look rational, rather than making genuinely rational decisions,” says Mercier.

The flip side, of course, is that we also face the risk of being duped by others, so we developed a healthy scepticism and an ability to see the flaws in others’ reasoning. This ability to argue back and forth may have been crucial to humanity’s success – allowing us to come to extraordinary solutions as a group that we could never reach alone.

Primates living in a large group have to form and maintain alliances, track who owes what to whom, and keep alert to being misled by others in the group. Sure enough, there is a very clear correlation between the number of individuals in a primate group, and the species’ average brain size, providing support for the “social brain” – or “Machiavellian intelligence” – hypothesis (New Scientist, 24 September 2011, p 40).

The evolution of language a few hundred thousand years ago would have changed the rules of the game….”Providing and evaluating reasons is fundamental to the success of human communication,” says Sperber, who has spent years considering the ways an argumentative mind might ease our way through the “bottleneck of distrust”, as he calls it.

On the one hand, a healthy scepticism would have been essential, leading us to more critical thought. Equally beneficial, however, would have been an ability to persuade others and justify our point of view with the most convincing arguments. It was Mercier who began to wonder whether this need to sway other people’s opinions might explain some of our biases, which might skew our logic but which may nevertheless give us the edge when arguing our opinions. So the pair set about reviewing an enormous body of psychological studies of human reasoning.

Consider the confirmation bias. It is surprisingly pervasive, playing a large part in the way we consider …behaviour …Yet people rarely have any awareness that they are not being objective. Such a bias looks like a definite bug if we evolved to solve problems: you are not going to get the best solution by considering evidence in such a partisan way.

But if we evolved to be argumentative apes, then the confirmation bias takes on a much more functional role. “You won’t waste time searching out evidence that doesn’t support your case, and you’ll home in on evidence that does,” says Mercier.

Mercier and Sperber offer a similar explanation for the “attraction effect” – when faced with a choice between different options, irrelevant alternatives can sway our judgement from the logical choice. It is perhaps best illustrated by considering a range of smartphone contracts: people who would tend to choose the cheapest option can be persuaded to opt for a slightly up-market model if an even more expensive, supposedly luxury model is added to the mix (see “Decisions, decisions”).

Playing defensive
According to Mercier and Sperber’s argumentative theory, the luxury option might sway our decision by offering an easy justification for our decision to go with the middle option – we can use it to claim that we have landed a bargain. Notably, the attraction effect is strongest when people are told that they will have to defend publicly whatever choice they make.

“…reasoning plays its argumentative role and drives you towards decisions that you can easily justify rather than the best decision for you,”

the argumentative theory offers a new twist, suggesting that participants in these experiments choose the response that will be easiest to justify if challenged…experiments have shown that people are more susceptible to the bias when they are told that they will have to defend their decision, just as you would expect if we evolved to convince others of our actions (Journal of Behavioral Decision Making, vol 20, p 125). The effect may weigh heavily on the way we weigh up the benefits and risks of certain lifestyle choices – it is the reason that “90 per cent fat-free” food sounds healthy, when a product advertised with “10 per cent fat content” would seem less attractive.

Drawing together all the difference strands of evidence, Mercier and Sperber published a paper in Behavioral and Brain Sciences journal last year outlining their theory (vol 34, p 57). In addition to confirmation bias and the framing and attraction effects, they cited many other seemingly irrational biases that might be explained by our argumentative past, including the sunk-cost fallacy – our reluctance to cut our losses and abandon a project even when it would be more rational to move on – and feature creep, which includes our tendency to buy goods with more features than we would ever actually use.

The paper has caused quite a stir since it was published. Jonathan Haidt, a moral psychologist at the University of Virginia in Charlottesville, believes the theory is so important that “the abstract of their paper should be posted above the photocopy machine in every psychology department”. Mercier and Sperber’s ideas dovetail neatly with Haidt’s influential view that our moral judgements stem from our gut reactions to moral transgressions, and not from rational reflection. In one example, Haidt and Thalia Wheatley of Dartmouth College in Hanover, New Hampshire, showed that hypnotically inducing the feeling of disgust leads people to make harsher moral judgments, even in cases when no one has done anything wrong – supporting the idea that emotion rather than logical reasoning drives morality (Psychological Science, vol 16, p 780). We still spend masses of time arguing about the morality of certain situations – …we are simply trying to justify our gut reactions and persuade others to believe our judgments, rather than attempting to come to the most just conclusion.

“Moral argumentation is not a search for moral truth, but a tool for moral persuasion,” says Haidt.

we evolved to argue and persuade, sometimes at the expense of the truth, may seem to offer a pessimistic view of human reasoning.

But there may also be a very definite benefit to our argumentative minds – one that has proved essential to our species’ success. Crucial to Sperber and Mercier’s idea is the fact that we are not only good at producing convincing arguments, but we are also adept at puncturing other people’s faulty reasoning. This means that when people get together to debate and argue against each other, they can counterbalance the biased reasoning that each individual brings to the table.

As a result, group thinking can produce some surprisingly smart results, surpassing the efforts of the irrational individuals.

When thinking about (a) task on their own, less than 10 per cent of people got the right answerWhen groups of 5 or 6 people tackled it, however, 75 per cent of the groups eventually succeededthis was not simply down to smart people imposing the correct answer on the rest of the group: even groups whose members had all previously failed the test were able to come to the correct solution by formulating ideas and revising them in light of criticism (Thinking and Reasoning, vol 4, p 231)There is also good evidence that groups are more creative than individual lone thinkers

Collective Intelligence
a group’s performance bears little relation to the average or maximum intelligence of the individuals in the groupInstead, collective intelligence is determined by the way the group argues – those who scored best on her tests allowed each person to play a part in the conversationsThe best groups also tended to include members who were more sensitive to the moods and feelings of other peopleGroups with more women, in particular, outperformed the others – perhaps because women tend to be more sensitive to social cues (Science, vol 330, p 686).

[We are likely] a species that evolved not to think individually, but to argue in groups.

“We think that argumentation evolved to improve communication between individuals, helping communicators to persuade a reticent audience, and helping listeners to see the merits of information offered by sources they might not trust…As a side effect, you get better reasoning in a group context.”

“The problem is that in many high-stakes situations, vested interests and emotions run high…..In these situations, people egg each other on to more extreme positions, while more moderate thinkers are chased out,”

when children think together,
they engage with tasks more effectively, and use better reasoning as they solve problemsThe results are striking in science and mathematics problemsnot only do groups often do better on these task, but individuals who participate in group reasoning also end up doing better in their exams in these subjectsSimilar improvements can be seen in the kinds of non-verbal reasoning tasks used in IQ tests.

“Kids can learn to see group reasoning as a kind of enlightened self-interest that benefits everyone,” says Mercer.

His work suggests a few pointers to get the best results.

Group reasoning was most productive when the children were asked to engage in “exploratory talk”where ideas can be openly aired and criticisedand when they entered the task with the clear goal of seeking agreement, even if this goal remained elusive.

Although such collaborative forms of teaching have gained some measure of popularity in recent years, Sternberg believes educational systems are still too focused on developing individual knowledge and analytical reasoning – which, as the research shows, can encourage us to justify our biases and bolster our prejudices.

“We believe that our intelligence makes us wise when it actually makes us more susceptible to foolishness,” Puncture this belief, and we may be able to cash in on our argumentative nature while escaping its pitfalls.

Dan Jones is a writer based in Brighton, UK


Written by Rich and Co.

May 29, 2012 at 7:34 pm

Posted in Uncategorized

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