The Republican Brain: The Science of Why They Don’t Believe in Science, by Chris Mooney, Wiley RRP £17.99, 310 pages

The Righteous Mind: Why Good People are Divided by Politics and Religion, by Jonathan Haidt, RRP Allen Lane £20, 419 pages

In March, about 3,000 delegates gathered in London for the Planet Under Pressure conference, the largest scientific meeting ahead of the Rio+20 summit on sustainable development, which will take place in June.

The conference’s final declaration was stark: “Research now demonstrates that the continuing function of the Earth system as it has supported the wellbeing of human civilisation in recent centuries is at risk.” But across the numerous panels and presentations on every aspect of climate change, biodiversity, food and water security, one frustration was voiced repeatedly: why, as the evidence base hardens, does public and political resolve to tackle these issues appear to be weakening?

This tendency is most marked among conservatives in the US, where increasingly partisan debates over climate change and the teaching of evolution have fostered a culture of unprecedented hostility towards certain areas of science. Quite how far the centre of gravity has shifted was illustrated when Jon Huntsman, the former US ambassador to China and an early contender for the 2012 Republican presidential nomination, used his Twitter feed to announce in August 2011: “I believe in evolution and trust scientists on global warming. Call me crazy.”

Many rightwing commentators did just that, warning that such explicit endorsement of the scientific consensus on these issues spelt the end of his campaign. And while the fiercest critics of climate change have also now dropped out of the race to be Republican presidential candidate, Mitt Romney, the presumptive nominee, has been forced to adopt a more sceptical stance, insisting in October that “we don’t know what’s causing climate change”.

Such shifts are normally analysed in political or cultural terms but, as Chris Mooney and Jonathan Haidt argue in this important pair of books, we need to turn to advances in psychology and neuroscience for a richer explanation of what is going on.

In The Republican Brain, Mooney, who came to prominence with his 2005 book The Republican War on Science, sets out “to investigate the underlying causes for the conservative denial of reality that we see all around us”. Drawing on a growing body of empirical research, he provides an intelligent, nuanced and persuasive account of how conservatives and liberals tend to differ at the level of psychology and personality. Liberals consistently display higher levels of “openness to experience”, one of five core personality traits, which means they are more receptive to new ideas, risk taking, variety and ambiguity. By contrast, conservatives are usually less open and more “conscientious”, with a greater appreciation of order, structure and certainty.

These traits shape the way people process and respond to information, with emotions over-riding reason: “Not only do we feel before we think – but most of the time, we don’t even reach the second step.”

This means that pre-existing beliefs are often more significant than facts in determining what evidence people will be persuaded by. Indeed, factual arguments may trigger what Mooney calls a “backfire effect”, where those with strongly held beliefs “not only fail to change their mind but hold their wrong views more tenaciously after being shown contradictory evidence”.

Mooney is careful to avoid a slide into reductionism; repeatedly emphasising that while insights from psychology, neuroscience and even genetics are relevant to understanding the causes of political disagreement, they don’t provide simple or complete answers.

To reinforce this point, he devotes a section of the book to wider factors in US political culture, such as the rise of rightwing think-tanks and partisan media, such as Fox News, which “interact with conservative psychology in such a way as to make the misinformation problem worse”.

He also highlights how liberals can display their own patterns of biased reasoning. Yet, despite these attempts at balance, and an admission that writing the book left him with a “new-found admiration” for conservatives, Mooney anticipates that many on the right will attack the book without properly reading it – observing wryly that this behaviour will only reinforce his case.

If the breadth of Mooney’s argument forces him at times to paint in sweeping, colourful strokes, Jonathan Haidt, professor of psychology at the University of Virginia, provides the finer, more detailed brushwork. In The Righteous Mind, he draws primarily on his own pioneering work in social psychology to explain how morality “binds and blinds”. His book, which is already creating waves among the political classes on both sides of the Atlantic, employs a striking series of metaphors.

First, he explains how our intuitions override reason, by suggesting that “the mind is divided, like a rider on an elephant, and the rider’s job is to serve the elephant”. He goes on to describe how “the righteous mind is like a tongue with six taste receptors”, but whereas liberals tend to rely on just two of these receptors, conservatives understand all six.

Liberals wrongly assume that their values are universal, whereas in fact they are weird, reflecting those who are “Western, Educated, Industrialised, Rich and Democratic”. Finally, he argues, “we are 90 per cent chimp and 10 per cent bee”, driven largely by selfishness, but with the capacity to work co-operatively like bees in a hive.

As psychology and biology encroach on politics, there is perhaps a danger that those on opposing sides will decide there is no point in attempting to overcome these intrinsic differences. Haidt and Mooney reject such pessimism: both end with impassioned pleas for tolerance and engagement, for a culture that values difference, recognises limits and learns to disagree more constructively. These are arguments with obvious relevance in a US election year, but they deserve a wide readership among all those who care about the quality and civility of our politics.

James Wilsdon is professor of science and democracy at the University of Sussex

Get alerts on Non-Fiction when a new story is published

Copyright The Financial Times Limited 2019. All rights reserved.

Follow the topics in this article