Cognitive ability and voting: Is there causation, or even correlation?

The matter of cognitive ability or IQ for Trump supporters comes up occasionally. My understanding was that cognitive ability is not strongly causally or correlatively related to any particular political or economic ideology, mindset or candidate. But is that belief supported or contradicted by modern research? 

Remember, correlation is not necessarily causation. One needs to be very careful about that concern when it comes to politics, IQ and a lot of (most?) other psychological, cognitive and social science research.

A 2022 paper:

Do Smarter People Have More Conservative Economic Attitudes? 

Assessing the Relationship Between Cognitive Ability and Economic Ideology

Evidence on the association of cognitive ability with economic attitudes is mixed. We conducted a meta-analysis (k = 20, N = 46,426) to examine the relationship between objective measures of cognitive ability and economic ideology and analyzed survey data (N = 3,375) to test theoretical explanations for the association. The meta-analysis provided evidence for a small positive association with a weighted mean effect size of r = .07 (95% CI = [0.02, 0.12]), suggesting that higher cognitive ability is associated with conservative views on economic issues, but effect sizes were extremely heterogeneous. Tests using representative survey data provided support for both a positive association of cognitive ability with economic conservatism that is mediated through income as well as for a negative association that is mediated through a higher need for certainty. Hence, multiple causal mechanisms with countervailing effects might explain the low overall association of cognitive ability with economic political attitudes. 

In the political arena, actors often describe their opponents as incompetent or stupid. Indeed, empirical evidence supports the view that a link between cognitive abilities and political attitudes exists. More specifically, most studies indicate that lower cognitive abilities are linked to the endorsement of conservative political views. However, a closer inspection of the evidence on the ideology-ability link reveals that the association between lower scores in cognitive ability tests and conservative political preferences holds in particular for sociocultural attitudes while the evidence with respect to economic attitudes is much more inconsistent. In fact, some studies indicate that the correlation between cognitive abilities and economic conservatism tends to be positive rather than negative. 

Currently, a large body of work indicates a negative association between measures of cognitive ability and the endorsement of conservative sociocultural attitudes. For example, higher scores in right-wing authoritarianism have been shown to be associated with lower scores in cognitive tasks. In a large-scale, nationally representative UK sample, lower general intelligence in childhood has been found to predict the endorsement of conservative ideology at an adult age when controlling for education and socioeconomic status. With respect to voting behavior, lower cognitive abilities were associated with more intentions to vote for Donald Trump and less intentions to vote for Hillary Clinton in the 2016 US presidential elections through effects on right-wing authoritarianism and social dominance orientation. (citations omitted)

That seems to indicate that there probably is a correlation between lower cognitive ability and endorsement of conservative sociocultural attitudes in politics, but maybe no correlation for conservative economic beliefs. 

A 2023 book chapter:

Politics and Intelligence: Running Against the Cognitive Elite

The 2016 election split the country in large part across educational lines. According to the statistician Nate Silver’s analysis, Clinton won handily in the fifty most well-educated counties in the nation, while Trump similarly prevailed in the fifty least. In Berkeley, home of the nation’s most prestigious public university, Clinton received ninety percent of the vote, while Trump, with three percent, finished third, behind the Green Party candidate. White men without college degrees voted for the Republican candidate at the highest rate since exit polls began; when Trump famously proclaimed his love for “the poorly educated,” it was not without ample justification. .... In a geographical reflection of this educational divide, Trump carried those areas well outside the city center that still relied substantially on manufacturing—the blue-collar workers who had constituted the Democratic base half a century earlier—while the Democrats were now what a Stanford political scientist called “the party of urban, postindustrial America.”

In classic populist fashion, Trump exploited this educational division to create a narrative of conflict between a privileged, parasitic elite, undeserving of its position, and the common folk—between a highly educated but aloof class of people who exercised power to their own advantage as multicultural, global citizens, and the real Americans, a silent majority who sensed instinctively what was right for the country without having to rely on “expert”—i.e., elite—advice. As Trump himself expressed it in the Wall Street Journal six months before his election, “The only antidote to ruinous rule by a small handful of elites is a bold infusion of popular will. On every major issue affecting this country, the people are right and the governing elite are wrong.” People in general in this rhetoric were not meant to be synonymous with “the people,” only some of the former qualifying for inclusion in the latter.

Thus, rather than campaigning on any substantive agenda, Trump ran as a representative of an aggrieved minority resentful of the worldview espoused by The Bell Curve, in which differences in intelligence are offered as justification not only for income inequality but for differences in social status. Neither the book nor its remaining author was mentioned during the campaign, and Trump’s frequent reference to the “elite” was never preceded by the word “cognitive”; indeed, given his limited range of information, it is possible that the future president was not even aware of the academic controversy. But it was clear that this notion of an elite—a “natural aristocracy,” as Herrnstein and Murray had put it—entitled by intellect and education to its prerogatives, provided Trump with a foil against which he posed as avatar of the rage of those average people who sensed their exclusion from this favored group; Trump’s policies might not help them, but he hated the same people they did. Instead of recognizing the “hoi aristoi,” as The Bell Curve had predicted, the “common people” apparently resented them, and the fact that Trump’s opponent, clearly considering herself a member of the elite, characterized so many of his supporters as “deplorables” only served to confirm these feelings of resentment on their part.

From what I can tell, as a group America's rich and/or powerful elite are privileged. In my firm, evidence-based opinion, they have rigged society and our system of government and commerce to further increase their already massive wealth and power. But does that group as a whole, however it is defined, have high cognitive ability compared to the average or the median score? Low education does not necessarily mean low cognitive ability.

A 2024 paper:

Intelligence is correlated with a range of left-wing and liberal political beliefs. This may suggest intelligence directly alters our political views. Alternatively, the association may be confounded or mediated by socioeconomic and environmental factors. We studied the effect of intelligence within a sample of over 300 biological and adoptive families, using both measured IQ and polygenic scores for cognitive performance and educational attainment. We found both IQ and polygenic scores significantly predicted all six of our political scales. Polygenic scores predicted social liberalism and lower authoritarianism, within-families. Intelligence was able to significantly predict social liberalism and lower authoritarianism, within families, even after controlling for socioeconomic variables. Our findings may provide the strongest causal inference to date of intelligence directly affecting political beliefs.

Two meta-analyses of this literature have been performed. Onraet et al. (2015) meta-analysis found intelligence to be negatively correlated with right-wing ideological attitudes (r = .20). However, the correlation depended on the type of right-wing attitude measured, with higher correlations with authoritarianism (r = .30) and ethnocentrism (r = .28) compared to conservatism (r = .13). Jedinger and Burger (2022) found a very small but significant correlation between intelligence and fiscally conservative beliefs (r = .07). Overall, intelligence has been found to be associated with beliefs that can be described as socially liberal and possibly also fiscally conservative. 

Although IQ is known to be associated with political belief, it is not known why this is the case. The relationship between intelligence and political belief could be confounded or mediated by socioeconomic factors and environmental factors more broadly. In this study, we employ polygenic scores, within-family designs and controls to causally identify the direct effect of cognitive ability on political beliefs. We might believe intelligence directly changes political beliefs. Political beliefs likely reflect our ethical values and our empirical beliefs, both of which might be altered by intelligence. Intelligence is related to greater general knowledge (Furnham & Chamorro-Premuzic, 2006), knowledge of economics (Caplan & Miller, 2010) and financial literacy (Lin & Bates, 2022). Moreover, intelligence may be related to subjective values, as it shows correlations with patience (Shamosh & Gray, 2008), openness (Anglim et al., 2022), “emotional intelligence” (MacCann, Joseph, Newman, & Roberts, 2014) and moral judgement in the Defining Issues Test (Derryberry, Jones, Grieve, & Barger, 2007). Onraet et al. (2015) suggested that the use of stereotypes and socially conservative beliefs function as heuristics, utilizing fewer cognitive resources than thinking about social issues on a case-by-case base. This could cause lower cognitive ability to be associated with right-wing views.

Genotypic IQ had a significant effect on all our measures of political beliefs: political orientation, authoritarianism, egalitarianism, social liberalism, fiscal conservatism and a composite of these scales. Across all these traits, genotypic IQ was associated with left-wing beliefs. After we controlled for the average parental polygenic score, we found genotypic IQ still significantly predicted social liberalism, the political composite, and lower levels of authoritarianism. Consistent with Onraet et al. (2015) meta-analysis, we find the largest effect sizes for authoritarianism rather than other measures of ideology.

The authors here argue that higher cognitive ability causes belief in social liberalism and especially lower authoritarianism. That seems to be the general belief that social science research is coming to adopt. Conservative and radical right authoritarian groups and think tanks might push back against this, but maybe that would be expected.

I'll do a separate post about cognitive ability among high income earners. That is important because top earners and wealth generally has more a lot influence on politics and policy than public opinion or social or environmental needs.