This isn’t just my anecdotal impression. A paper by Light, Fernbach, Geana, and Sloman shows that opposition to the consensus is positively correlated with knowledge overconfidence. Now you may wonder. Isn’t this circular? If someone claims the consensus view is wrong we can’t just say that proves they don’t know what they are talking about. Indeed. Thus Light, Fernbach, Geana and Sloman do something clever. They ask respondents a series of questions on uncontroversial scientific topics. Questions such as:
1. True or false? The center of the earth is very hot: True
2. True or false? The continents have been moving their location for millions of years and will continue to move. True
3. True or false? The oxygen we breathe comes from plants: True
4. True or false? Antibiotics kills viruses as well as bacteria: False
5. True or false? All insects have eight legs: False
6. True or false? All radioactivity is man made: False
7. True or false? Men and women normally have the same number of chromosomes: True
8. True or false? Lasers work by focusing sound waves: False
9. True or false? Almost all food energy for living organisms comes originally from sunlight: True
10. True or false? Electrons are smaller than atoms: True
The authors then correlate respondents’ scores on the objective (uncontroversial) knowledge with their opposition to the scientific consensus on topics like vaccination, nuclear power, and homeopathy. The result is striking: people who are most opposed to the consensus (7, the far right of the horizontal axis in the figure below) score lower on objective knowledge but express higher subjective confidence. In other words, anti-consensus respondents are the most confidently wrong—the gap between what they know and what they think they know is widest.