Steve asked:

In the scientific debate over anthropogenic climate change, there are two opposing views. Advocates and deniers with attitude polarisation occurring on both sides. How do I decide which group are ‘victims’ of confirmation bias and where do I place my confidence?

Answer by Shaun Williamson

There is no scientific debate over climate change. The vast majority of the world’s climate scientists are on the advocates side. The oil and coal industry may try to persuade you that there still is a debate but there isn’t.

There are some things you need to keep in mind about this.

1. This isn’t just a fun debate, if we get it wrong then we may make the planet uninhabitable. It might be best to err on the side of caution.

2. Just as the tobacco industry was prepared to swear to Congress that they didn’t think smoking caused cancer (even though later evidence showed that they didn’t believe this), so the oil and coal industry are prepared to spend vast sums of money to bribe politicians not to do anything about climate change and they will do anything to persuade you that this is still an open debate.

If you really need to know the truth then become a climate scientist. If you just want to be a reasonable human being then err on the side of caution and go with the vast majority of the world’s qualified climate scientists.

Answer by Craig Skinner

You say two opposing views in the SCIENTIFIC debate. This is a bit like claiming two opposing views in the scientific debate about evolution.There aren’t. Rather there is an overwhelming PRO consensus and a fringe CON view. And I suspect such is the case with climate change, albeit the scientific PRO view is less overwhelming than with evolution.

The opposing views occur in political or popular debate, although here protagonists typically try to represent slight contrary evidence as an opposing scientific view, such is the prestige of science.

How to decide which groups are victims of confirmation bias?

The latter is a hard-wired feature of normal human cognition, presumably because it was a mindset of survival value in our ancestors. We are all ‘victims’. The brain is a belief organ. It looks for patterns, gives them meaning and forms beliefs. Then we subconsciously seek out confirmatory evidence to reinforce them.

Science is the best tool we have devised to determine whether our beliefs match reality. It systematically deals with confirmation bias, particularly by recognizing the power of refutation (note the asymmetry between confirmation and refutation – many ‘confirmatory’ instances merely give further support to a view; a single refuting instance falsifies the view). So, testing against the empirical world systematically roots out error (refutation) while ‘confirmation’ never quite reaches certainty (although doubtless many scientific views are in fact true).

I say science does this rather than scientists. The latter are as prone to confirmation bias as anybody else, but at least are signed up to a method of dealing with it.

So where do you place your confidence? You have two choices:

1. Gather and assess the evidence yourself. This is fine for limited areas where you have expertise or are willing to work to acquire it.

2. Accept the assessment made by people you trust to make a fair job of collecting and interpreting the evidence.

Not politicians, who are in the business of persuasion and mostly cast around for selective evidence to support pre-existent views.

Although Individual scientists may be cranks with idiosyncratic views (but are occasionally right), a scientific consensus is a reasonable basis for provisional belief and, importantly, for action.

On a practical level, scientists only occasionally write a consensus view which is a page-turner (eg Steve Jones, Sagan, Dawkins, Rees). This job is usually better done by science writers (eg Gribbin, Singh, Matt Ridley)

‘A wise man proportions his belief to the evidence’. Such was the dictum of the greatest English-speaking (Scottish) philosopher David Hume. A sound maxim, even, in suggesting degrees of belief, foreshadowing the Bayesian approach of prior probability adjusted to posterior probability by new evidence.