What is the average IQ of holocaust deniers?

A first estimate

I made a troll poll on Twitter, and it's going well.

100s of those people showed up in the replies to insult me or provide stupid arguments for why it is wrong (almost all of them are in the form of "what about smart person X who was an anti-Semite"). That was of course the intention. Their response to the poll demonstrated that the value could not be above 100.

Just out of curiosity, I looked around in various datasets and studies, and there doesn't seem to be any study of the IQs of holocaust deniers (or revisionists) in itself. There are a few studies of IQ and conspiracy theories in general. In the first study of 475 British people, researchers correlated self-report measures of personality disorders and 15 conspiracy theories as well as IQ:

CT is conspiracy theories, which correlated -0.14 with IQ (-0.17 with education), 0.28 with cluster A and 0.19 with cluster B ("Clusters A (Odd and Eccentric) and B (Dramatic and Emotional) ... and Cluster C (Emotional)"). A correlation of 0.14 corresponds to about 0.28 d, or 4,2 IQ. But it's a 10-item IQ test, so adjusted for reliability, it would be larger, assuming reliability 0.70, it would be 5 IQ.

In the second study, part of a longer rationality scale (CART), had 24 conspiracy beliefs:

There are twenty-four items on the Conspiracy Beliefs subtest of the CART (see the appendix for sample items). We drew on a large number of conspiracies studied in the literature (Goertzel, 1994; Lewandowsky, Oberauer, & Gignac, 2013; Oliver & Wood, 2014), and added a few new ones of our own. Our subtest covered a wide range of conspiratorial beliefs. Most importantly, it covered conspiracies of both the political left and political right. Unlike some previous measures, it was not just a proxy for political attitudes (see Brandt et al., 2015; Chambers, Schlenker, & Collisson, 2013; Kahan, 2013; Oliver & Wood, 2015). Some of the commonly studied conspiracies that we assessed were: the assassination of President John F. Kennedy, the 9/11 attacks, fluoridation, the moon landing, pharmaceutical industry plots, the spread of AIDS, oil industry plots, and Federal Reserve conspiracies.

This was given to a sample of 377 American university students:

Table 10.1 presents the correlations between the raw score on the Conspiracy Beliefs subtest and the other variables in this study. As expected, the Conspiracy Beliefs subtest correlated (p < 0.001) with both the raw Superstitious Thinking subtest score (r = 0.32) and the raw Antiscience Attitudes subtest score (r = 0.26). Also as expected, the latter two subtests correlated with each other (r = 0.20, p < 0.001). Because these three subtests were self-report questionnaire measures, we were concerned about social desirability/impression management issues contributing to the variance. Therefore, in this and other studies, we have included a ten-item Impression Management scale (Cronbach’s alpha = 0.72) adapted from the work of Paulhus (1991). The next line in table 10.1 indicates that impression management was not highly associated with responses on these three subtests. Two of the three correlations were not significant even with this substantial sample size, and the third was –0.14 (p < 0.01.); in the latter case, higher impression management was associated with rejection of superstitious thinking.

There's the SAT (excellent IQ measure), financial literacy and probabilistic numeracy, all of which correlated negatively, and positive correlations with other irrational attitudes. These values again suggest a value about 5 IQ lower than average.

Now, one might claim that holocaust denial is special and doesn't follow this general pattern. So let's look at the world map and see if that looks sensible. It seems hard to find proper national studies of holocaust denials, but the ADL (yes I know) funded a global survey, and this is the summary:

A new survey by the Anti-Defamation League shows that 4 percent globally deny today that the Holocaust happened. This number was 5 percent among men and 5 percent among people between the ages of 18 and 49. While in Asia and Sub-Saharan Africa, rates of Holocaust denialism were average, they were elevated in North Africa and the Middle East. They were at below-average rates in Western Europe (1 percent of respondents). However, many more respondents said they believed that the number of victims of the Holocaust had been greatly exaggerated. This reached as high as a third of respondents in North Africa and the Middle East, 18 percent in Asia, 16 percent each in Eastern Europe and Sub-Saharan Africa and even 15 percent in the Americas.

The survey also asked respondents if they agreed with any out of 11 stereotypes about Jewish people and asked questions about the acceptance or rejection of Israel. It found that people had especially strong antisemitic beliefs in the Magreb states and the Middle East, but also in Russia, Indonesia, Malaysia and Turkey. The survey found that younger people were more likely to show antisemitic attitudes. While the average country scored 26 out of 100 points in the survey in 2014 (with 100 being the worst result), this had changed to an average score of 46 out of 100 in 2024.

The ADL is Jewish lobby organization, so it is somewhat ironic to rely on numbers they paid for considering that their attack dogs often attack me as well. Anyway, putting the numbers together, we can now make a reasonable estimate of the aveage IQ of holocaust deniers. One can use either the strict or broad definition based on the above values, and compute a mean IQ. I asked Grok to give me the population of those regions, and I ballpark estimated the regional mean IQs as 95 (USA and Canada pulls up, the others pull down), 89 (Northeast Asia pulls up, especially China, the others pull down), 100, 95, 84, 70. Doing so, and calculating weighted means for the fraction with those beliefs, you get estimates of 86 and 87 IQ. Now, based on the conspiracy belief and IQ correlation, those people are likely to be somewhat below average, maybe about 5 IQ, at least inside the west. Doing so would give an estimate of 80-85 IQ.

One doesn't really need to do these calculations specifically to know that the IQ is in that range because a moment's reflection would immediately tell you that holocaust denial is most common in the Muslim world because these are the most anti-Jewish people, and the mean IQ there is about 80-85, so one could simply adopt that as the guess and it would be approximately correct as well. That is what most people on Twitter failed to do, even some otherwise reasonable posters who replied to my poll.