Why do smart people believe conspiracy theories?
The comfortable answer — that believers are simply less intelligent — is wrong. Conspiracy belief has a biography, and it often starts decades before the first conspiracy theory is encountered.
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It starts earlier than you think
The most striking evidence I know of comes from following the same Norwegians for over thirty years: loneliness trajectories from adolescence onward predict conspiracist worldviews in midlife. People who were chronically lonely as teenagers were measurably more likely, decades later, to see the world as run by hidden hostile forces. That reframes conspiracy belief as something with developmental roots — and it moves prevention back in time, toward adolescent social connection rather than adult fact-checking alone.
Feeling outnumbered — even when you are not
Belief also tracks how people locate their own group in society. Perceiving your own group as a minority is linked to conspiracy thinking — and remarkably, this holds even when the group is factually a majority. What matters is the felt position: embattled, overlooked, losing ground. A conspiracy theory then does real psychological work, because it explains that feeling and assigns it an author.
Being fooled and refusing truth are different failures
It is tempting to imagine one dial labelled 'gullibility'. Our work suggests otherwise: there are distinct phenotypes of susceptibility to true and false information — accepting falsehood and rejecting truth are separable errors with different cognitive and personality profiles. Susceptibility is not even fixed within a person: studies link sertraline treatment and tobacco smoking to measurable shifts in it, which means credulity behaves more like a cognitive state than a character trait. 'Smart people' believe conspiracy theories because intelligence was never the relevant variable.
Does it actually change behaviour?
Yes — measurably. Our meta-analysis of conspiracy beliefs during COVID-19 found they translated into reduced social distancing over time, not just into talk. As for what helps, a scoping review of psychological interventions against misinformation on social media reaches a sober conclusion: the effects of inoculation and debunking are modest but real. I think that conclusion is worth defending against both the hype and the dismissal — and it is one reason my current work focuses on what happens when the machinery producing false claims stops being human.