Conspiracy beliefs are individuals’ acceptance of specific conspiracy theories as likely true. […] Of course, polling leaves room for interpretaion. First, how a survey item is worded can affect if the idea being asked about is a conspiracy theory or not. Note the difference between survey items that ask respondents to express agreement with: ‘Vaccines cause autism’ or with ‘Pharmaceutical companies and governments are actively working to hide the dangerous effects of vaccines from the public’. The latter expresses a conspiracy theory, the former does not […]. Second, what level of certainty qualifies as a belief? Consider a question asking respondents about the ‘Chem-trail’ conspiracy theory. One version of this question asked respondents to agree or disagree with the theory; 5 per cent agreed […]. Another version asked respondents to answer on a Likert scale from ‘completely false’ to ‘completely true’. Researchers then asked ‘unsure’ respondents to make a best guess […]. The result was that 40 per cent of the total sample indicated the theory was ‘completely’ or ‘somewhat true’. The different ways of operationalising belief lead to estimates that varied by a factor of eight […]. The 5 per cent and 40 per cent groups will likely vary greatly in terms of their demographic characteristics, and it is not clear which group is the ‘right’ one to consider as the conspiracy theorists. Third, it is important to note that people selectively believe in conspiracy theories. There are an infinite number of conspiracy theories, but surveys can only ask about one or a few. This means that some people who are certainly ‘conspiracy theorists’ (under some definition) will show no evidence of such on some surveys, and vice-versa.
[…]
So, who, then, is a conspiracy theorist? It is with this term that definitions vary the most. Conspiracy theorist could refer to anyone who believes in any conspiracy theory. Presumably, most people are not conspiracy theorists. Yet, polls suggest that basically all Americans hold conspiracy beliefs. […] The general trend is that, as more conspiracy theories are asked about, the number of people who believe one increases to approach 100 per cent. Therefore, using conspiracy theorist to refer to anyone who believes in any conspiracy theory is meaningless.
– ‘Who are the conspiracy theorists? Demographics and conspiracy theories’, in Routledge Handbook of Conspiracy Theories (2020), pp. 263-4
Conspiracy beliefs are partially dependent on demographic characteristics and group memberships because they cast one’s own group as a victim of other groups. Conspiracy beliefs therefore vary widely across race, region, social class, age, gender, religion and party identification […]. Christians and Muslims are more likely than Jews to believe in Jewish conspiracy theories […]; people with New Age beliefs more likely than Catholics to believe in DaVinci Code theories […], and partisans are more likely to believe the opposing party, rather than their own, is conspiring against them. For example, polls show that 45 per cent of Democrats believed that President Bush was behind the 9/11 attacks but only 15 per cent of Republicans believed as much; about 40 per cent of Republicans believed that President Obama was born outside of the U.S.A. but only 15 per cent of Democrats believed as much […].
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U.S. polling shows that conspiracy thinking is even between the two major parties and across political ideologies; independents and third parties tend to show higher levels of conspiracy thinking [Uscinski, J.E. and Parent, J.M. (2014) American Conspiracy Theories, New York: Oxford University Press].
– Ibid., pp. 265-7
From what we have outlined above, we can cautiously answer the question who is a ‘conspiracy theorist’. Conspiracy theorising is prevalent – most people believe at least one conspiracy theory, even in surveys that ask only about a few. Conspiracy thinking is more apparent in the marginalised – or those who think of themselves that way – populations. We do see a general correlation between conspiracy thinking and people who distrust their government. Conspiracy thinking is a worldview that often escapes any single socio-demographic categorisation, largely because it is so common even across cultural contexts.
– Ibid., p. 274