The man who called global warming a fabrication invented by the Chinese to make US manufacturing less competitive is now president-elect of the US. His followers expect him to withdraw the US from the Paris climate change agreement and eliminate the environmental regulations introduced by his predecessor.

But recently, Donald Trump has shown a few signs that he might be open to being convinced that climate change is a real problem requiring action. In discussion with journalists at the New York Times, he expressed the view that there is “some connectivity” between human activity and climate change, adding that he’s keeping an open mind about it.

Will his commitments on climate change go the way of his vow to prosecute Hillary Clinton? I doubt it. I suspect that in the end, the words of his close advisers will be more persuasive than those of climate scientists. He will retain only a figleaf of regulation, at best.

Trump often boasts of his intelligence. Many people might take his scepticism about climate change as evidence against his inflated sense of his own abilities. I don’t think it is. I have no high opinion of Trump’s intelligence, but scepticism about climate change is not the result of a lack of mental capacity or of rationality. The minds of sceptics are not working any less well than those who accept the consensus. They are more victims of bad luck than of bad thinking.

Left-right divide

In fact, there is little relationship between intelligence and knowledge and beliefs on climate change (or other hot button issues, such as evolution). It is political affiliation – and not knowledge or intelligence – that predicts attitudes concerning climate change.

Whereas for those on the left, more knowledge and higher intelligence predicts a higher rate of acceptance of the consensus, for those on the right the opposite is true. Sceptics are not less intelligent or less knowledgeable. Instead, our political biases strongly influence how we process information – and especially what sources we are likely to trust.

We get a great deal of information via the testimony of other agents. We have to. We can’t check everything out for ourselves. When we go to a doctor, we rely on their expertise to diagnose our ailment. We don’t have the time to do a medical degree ourselves. The doctor is in the same position with regards to their lawyer and mechanic. Even in their own field, they depend on the testimony of others: they likely have no idea how to construct an X-ray machine and may have little idea how to interpret an fMRI scan.

Contemporary societies, with their deep division of labour, make our reliance on others for knowledge obvious – but the phenomenon is not new. Even in traditional societies there is a division of labour as a result of the fact that some skills take a long time to acquire. So deep is our reliance on a division of knowledge-sector labour, we seem to have adaptations for acquiring beliefs from others.

Choosing who to believe

Though human beings are disposed to acquire beliefs from others, we do so selectively. From an early age – and to an extent that increases across childhood – we rely on certain cues to distinguish reliable from unreliable informants. Among the cues for reliability, two stand out: evidence of competence and evidence of benevolence. Children are more likely to reject the testimony of competent individuals who seem to them ill-motivated. That makes sense, of course – we want to be able to filter testimony so that we are not easily exploited.

EPA/Lindsay Parnaby

In his work on the partisan divide over matters of fact, American psychologist Dan Kahan suggests that testimony may play a role in explaining this divergence. As he says, both sides may defer in their beliefs to genuinely more competent people around them who share their political outlook. I suggest that the filters we apply in accepting testimony are at work here. We accept the testimony of those who give signs of greater competence than us and who are also benevolent to us and our interests: taking a shared political orientation as a proxy for benevolence seems a reasonable enough thing to do.

Liberals (using that word in the US sense) and conservatives come to their views on a wide range of issues, such as climate change, via testimony. And they do so in a way that is individually rational. They identify people who are genuinely more competent than they are and who give other signs of trustworthiness – and then they defer to them. If that’s right, then neither side can be said to be more rational than the other.

Merchants of doubt

But this doesn’t mean that beliefs – particularly on climate change – are equally justified by all the evidence. Beliefs we acquire via other people can be justified when they trace back to individuals – or, in this case more plausibly, groups of individuals – who have a demonstrable grasp of the issues and are able to present relevant evidence.

On the question of climate change, conservatives’ chain of testimony traces back to “merchants of doubt”, who may have deliberately and knowingly fabricated falsehoods, as well as cranks – and, yes, a very few genuinely knowledgeable people, who themselves dissent rationally. Liberals’ chain of testimony, meanwhile, traces back to a much broader set of genuinely expert people.

Daily Mail

Conservatives like Trump may thereby come to have false beliefs through no fault of their own. And it’s not just conservatives who are vulnerable to this kind of bad luck in belief. Merchants of doubt may find a hospitable environment on the left, too. That has probably happened less often in recent history, simply because it takes money to effectively hijack a debate and corporate interests have been aligned with the political right.

That may change, however. In the US, there is evidence that the Democrats are starting to become the party of the wealthy. Perhaps Trump’s election will reverse this trend – if it does not, moneyed interests may in future distort signals of benevolence so it is the left that finds itself defending nonsense.

Next, listen to our The Anthill podcast’s special episode on belief: from the allure of cults and conspiracy theories, to the effect of trauma on faith, to the way dogma has influenced science – and if technology can actually shift our beliefs.