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stig-hebbelstrup-rye-rasmussen-80x108Why do people vote for Hillary Clinton rather than Donald Trump? One of the most important reasons why people choose candidates and political parties is based on their positions on various political issues. Voters in general seek to choose the candidate which is the closest match to their own political attitudes. Stig Hebbelstrup Rye Rasmussen writes that not all voters perform this task equally well, and that one of the most important factors, and so far overlooked, is the role intelligence plays in determining which party best matches the political attitudes of the individual voter. 

Judging from the current debates surrounding the 2016 presidential election the different personas of Hillary Clinton and Donald Trump seem to be the primary factor in determining which party Americans will vote for.  While presidential attributes such as likeability and competence will play important roles when deciding how to vote come November, political scientists have traditionally put more effort in understanding the influence of ideological differences between candidates and in voters’ decisions. We know from a large literature that one of the most important factors voters shaping vote choices are their political attitude, such as whether they are in favor of redistribution or abortion.

The argument in its general form is quite simple: Voters should, when basing their vote choice on ideological affinities, vote for the party which best represents what they believe. This process of matching ideological attitudes to a party is often referred to as ideological voting. If I am a voter who favors a large amount of redistribution I should vote for the party which also favors redistribution. In the aggregate many studies have demonstrated that there is a strong link between the attitudes of the voters and the parties they end up choosing. When looked at this way everything is thus fine: Voters vote according to their attitudes. The problem however is that not all are equally capable of making the link between their own political attitudes and the correct party which best represents these interests and attitudes.

Traditionally researchers have focused on the important role differences in political knowledge, political interest and educational differences play in terms of predicting ideological voting, but none have looked at the (potentially) important role of intelligence. This is surprising since this is in essence what intelligence is all about: The ability to deduce the relationship between general (ideological) principles and concrete applications such as vote choices. In addition, intelligence is established early in life, quite stable over time, and highly heritable – it is thus likely to causally precede the other factors affecting ideological voting such as education and political knowledge.


To remedy this shortcoming in the literature I collected two datasets with my colleagues at the Centre for Political Psychology in Denmark: A Danish representative sample of young males and females who had taken the intelligence test at the Danish draft board, and an American Mturk sample, where the participants were also asked to complete an intelligence test. In addition we asked the respondents about their vote choices and their ideological attitudes. In the literature on ideological attitudes it is common to distinguish between economic attitudes, primarily attitudes toward economic redistribution and government support, as well as social attitudes, such as attitudes toward abortion and law and order.

I found that across both ideological dimensions and across both samples the effect of intelligence on ideological voting was equal in effect size to the traditionally strongest predictor of ideological voting in the literature so far: political knowledge. The influence of intelligence decreases when both political knowledge and intelligence are considered simultaneously which suggests that part of the reason why those who are more politically knowledgeable are better at ideological voting is because they are more intelligent. There is far from a one to one relationship between the two however, and each represents (partially) independent pathways to achieving ideological voting. In addition, the effect of intelligence was also quite consistently larger than education or political interest.

From a democratic perspective it is problematic if parts of the electorate systematically do not have their interests represented. If for instance people with low income, who tend to favor increased redistribution, consistently vote for a party which does not favor increased redistribution, or if this groups vote choices are random, this poses a democratic problem if those with high incomes consistently vote for parties which favor decreases in redistribution. In democratic terms there is nothing wrong with voting according to your preferences, interests and attitudes but it is a problem if the interests and preferences of some groups are weighed more heavily than others as this challenges the fundamental principle of political equality inherent in a democracy. Having found a so far unknown and very strong predictor of ideological voting is good news seen from a democratic perspective: There are more ways to make an informed vote choice than was previously known.

This article is based on the paper, ‘Cognitive Ability Rivals the Effect of Political Sophistication on Ideological Voting’, in Political Research Quarterly.

Featured image credit: Vox Efx (Flickr, CC-BY-2.0)

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Note:  This article gives the views of the author, and not the position of USAPP – American Politics and Policy, nor of the London School of Economics. 

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About the author

stig-hebbelstrup-rye-rasmussen-80x108Stig Hebbelstrup Rye RasmussenUniversity of Southern Denmark
Stig Hebbelstrup Rye Rasmussen is a post.doc at the Centre for Political Psychology at the University of Southern Denmark. His primary research interests are political psychology with a special focus on individual differences such as personality traits and intelligence as well as behavioral genetic research methods.