and the time elapsed since the alleged conspiracy, increases. This is a simple consequence of the assumption that in a given period of time, any one of the conspirators could let their secret slip, either by blowing the whistle or by committing some blunder. In addition, conspiracy theories concern plots that are believed to be so important that the public should—but do not—know about them. By definition therefore, they make claims that tend to contradict common wisdom as embodied in public opinion and institutional knowledge. The epistemic risk is aggravated by some of the other corollaries of conspiracy theories’ essential features. For example, they make auxiliary assumptions about the gullibility of the public; the extraordinary, unchecked dastardliness and competence of conspirators; and the relative unimportance of impersonal and systemic causes. These normative disadvantages of conspiracy theories are well documented (e.g., Clarke 2006, Sunstein & Vermeule 2009) and baked in.
None of this means that conspiracy theories are necessarily false, or even implausible. Because people do conspire, and we seldom witness the full causal chain leading to events of public interest, some conspiracy theories could in principle turn out to be true. Psychologists and other social scientists do not necessarily have privileged access to relevant evidence, so they are not necessarily in a better position than anyone else to judge the truth or plausibility of conspiracy theories. This makes truth or even plausibility more or less unworkable as a definitional criterion against which any single belief could be evaluated. For similar reasons, researchers working on related topics such as paranoia have abandoned truth or rationality as strict definitional criteria (e.g., Raihani & Bell 2019). We therefore disagree that conspiracy theories must, by definition, be untrue or implausible (e.g., Brotherton et al. 2013, Cassam 2019, Keeley 1999). Our claim instead is that conspiracy theories have features that tend to make them, as a class of beliefs, more prone to falsity. This epistemic riskiness can explain why other risky types of belief, including paranormal beliefs, and cognitive styles that emphasize intuitive appeal over rational analysis are among the strongest predictors of conspiracy belief (Biddlestone et al. 2022, Douglas et al. 2019).
Some further clarifying notes about our definition of conspiracy theories may be useful. Though we do not stipulate that conspiracy theories have to be untrue, we do require the conspiracies they describe to be of public interest but not public knowledge—i.e., that in general the public do not believe that the conspiracy has occurred. This means, for example, that the belief that 9/11 was orchestrated in secret by Al-Qaeda is not a conspiracy theory, because this theory is generally acknowledged by the public. It also means that the belief that the same event was orchestrated by Mossad is indeed a conspiracy theory. Very often, the truth and public knowledge correspond. So the untruth/implausibility criterion leads to much the same decisions on specific conspiracy theories as our public knowledge criterion. Further, we acknowledge that there are downsides to our public knowledge criterion. One of these downsides is that this criterion is fuzzy: How many people, which members of the public, which public institutions, and what degree of conviction are enough to disqualify a belief as a conspiracy theory? However, similar ambiguities surround truth and implausibility. For example, what type of evidence, what strength of evidence, and what criteria for implausibility are sufficient for a belief to be categorized or not as a conspiracy theory? Finally, since so much sensitivity surrounds conspiracy beliefs (e.g., Douglas et al. 2022, Lantian et al. 2018), we believe it is preferable for social scientists to avoid positioning themselves, inadvertently or not, as having a stake in the truth or falsity of conspiracy theories, even less being the arbiters of their truth or falsity. In our experience, many people—whether they reject or embrace conspiracy theories—view conspiracy theory researchers such as ourselves as having a stake in our object of study. This perception, of course, is not necessarily warranted. Researchers can study the causes, consequences, and communication of conspiracy theories, political ideologies, religious beliefs, or almost any attitude regardless of their own position. Since our methods and expertise do not allow us to determine whether conspiracy theories are true or plausible, and since these are
