How best to persuade people who do not accept scientific consensus

Since emotion plays a large part in motivating those who reject the consensus, then science communicators should also use emotion in making their case

There are several important reasons to enhance the public understanding of science, including explaining how the natural world works, explaining how everyday science-based technology works and encouraging young people to study science and take up the science careers. Science communication in this straight-forward sense is effective and simply means reducing the deficit of scientific knowledge in the public mind.

However, in particular cases some people dislike the implications scientific findings have for their ideology, worldview or other self-interest, and refuse to accept the science. In these cases the information-deficit model of science communication is ineffective. To paraphrase novelist Upton Sinclair: "It is impossible to make a man understand something if his self-interest depends on his not understanding it."

For example, there is a scientific consensus based on voluminous evidence that global warming is caused by human activity but many people (50 per cent of the public in America) reject this consensus. Finding ways for science to communicate more effectively with the public on such issues is an urgent priority.

In 2010 Yale psychologist Dan Kahan disproved the information-deficit model's claim that people refuse to accept a scientific consensus because they lack scientific knowledge and that explaining the scientific facts to them will change their minds. Kahan surveyed 1,500 Americans, classifying each person's culture worldview on a scale from conservative to politically liberal. He assessed each person's scientific literacy by asking questions such as "True or false: Antibiotics kill viruses as well as bacteria". He then asked about climate change. His reasoning was that, if the information-deficit model were right then, regardless of worldview, the more scientifically literate people would agree with the scientific consensus that climate change is human-induced and a serious risk to humanity.


But that’s not what Kahan found – people with contrasting political values draw different conclusions from the same scientific evidence even when they are scientifically literate. Scientific literacy seemed to increase polarisation, with the conservative leaning participants who knew most science, thinking climate change poses the least risk. In later research Kahan asked respondents what climate scientists believed. Those who knew most science identified the scientific consensus better, regardless of political leaning – the polarisation disappeared. Yet when the same people were asked their own opinions, the polarisation resurfaced. Even when people understand the scientific consensus, they don’t necessarily accept it.

So, if scientific facts will not persuade those who do not accept the scientific consensus on climate change, vaccinations, evolution, etc, what is the best approach? Well, the first thing I would say is that because scientific facts are culture-neutral objective information, these facts remain very important and must continue to be presented because we cannot allow misinformation to spread unchallenged. But, knowing that scientific facts alone will not quench the flames of resistance in many, this approach must be supplemented with another approach.

Science communicators should avoid framing issues in terms of left versus right or science versus “denialism” and should not brand people who reject the scientific consensus as “deniers”. Scientists should respectfully debate with the odd scientist who publishes peer-reviewed evidence contradicting the consensus position. Consensus scientists should never brand such dissenting scientists as “heretics”.

It also seems to me that, since emotion plays a large part in motivating those who reject the consensus, then science communicators should also use emotion in making their case. Scientists should explain why the scientific facts are important to them and why they should be important to the listener also. They should explain the health and economic consequences of climate change to the local community and the high probability that climate patterns severely inimical to human wellbeing will take over unless we take action very soon.

They should explain the economic boost that will be provided by renewable energy technologies. Scientists should emphasise that we are all in this together and our children will inherit the consequences of our actions or inactions. Most parents will go to great lengths to ensure their children will enjoy relatively small advantages in the near term. How then can parents refuse to take modestly inconvenient actions now to ensure that their children and grandchildren will not inherit a ruined world?

William Reville is an emeritus professor of biochemistry at UCC