have you ever thought that conservatives are all stupid?

you were right!

A paper, Conservativism and Cognitive Ability from the psychology journal Intelligence finds that

"Conservatism and cognitive ability are negatively correlated. The evidence is based on 1254 community college students and 1600 foreign students seeking entry to United States' universities. At the individual level of analysis, conservatism scores correlate negatively with SAT, Vocabulary, and Analogy test scores. At the national level of analysis, conservatism scores correlate negatively with measures of education (e.g., gross enrollment at primary, secondary, and tertiary levels) and performance on mathematics and reading assessments from the PISA (Programme for International Student Assessment) project. They also correlate with components of the Failed States Index and several other measures of economic and political development of nations. Conservatism scores have higher correlations with economic and political measures than estimated IQ scores.

1. Introduction
There has been an increased interest in the construct of conservatism. Recent evidence indicates that some existing stereotypes are not supported by the available data. For example, (Brooks, 2006) and (Brooks, 2008) reports that conservatives engage more than liberals in charitable activities and people on the political right are nearly twice as happy as those on the left. The work of Napier and Jost (2008) shows that conservatives tend to be happier than liberals because of their tendency to justify the current state of affairs and because they are less bothered by inequalities in the society. The focus of these investigators is on political conservatism — tendency to attach high importance to topics that are high on the agendas of right-wing political parties within a given society and, consequently, endorse these parties' candidates in elections. For example, a version of the USA Wilson–Patterson Conservatism Scale (WPC; see Wilson, 1973) used in a study reported by Bouchard et al. (2003) contained 28 items that asked participants to state how important topics such as abortion, property tax, gay rights, liberals and immigration are.1 In the studies reported in the main body of this paper, political conservatism was not examined directly. However, Jost, Glaser, Kruglanski, and Sulloway (2003) suggest that it is time to re-examine the links between political conservatism and a host of individual difference variables. A constellation of these individual difference variables may be called Conservative syndrome. Although an alternative label, psychological conservatism, may be more appropriate if one's aim is to contrast politics and psychology, the term syndrome appears to be adequate for a discourse within the field of psychology itself.

Jost et al.'s (2003) meta-analysis confirms that several psychological variables predict political conservatism. The list includes death anxiety; system instability; dogmatism; intolerance of ambiguity, low openness to experience, and uncertainty; need for order, closure, and negative integrative complexity; and fear of threat and loss of self-esteem. The theory of Jost et al. (2003) treats political conservatism as motivated cognition and builds on a large body of research accumulated since the end of World War II. One antecedent is the approach advocated by Wilson's (1973) dynamic theory that also saw conservatism as a motivated response to uncertainty. The threat or uncertainty may derive from fear of death, anarchy, foreigners, dissent, complexity, novelty, ambiguity, and social change. Responses to these sources of uncertainty include superstition, religious dogmatism, ethnocentrism, militarism, authoritarianism, punitiveness, conventionality, and rigid morality. Wilson postulated that political conservatism derives from genetic sources (anxiety proneness, stimulus aversion, low intelligence, and physical unattractiveness) as well as environmental influences (parental coldness, punitiveness, rigidity, inconsistency, and low social class). Jost et al. (2003) summarize their own position in the following way: “The core ideology of conservatism stresses resistance to change and justification of inequality and is motivated by needs that vary situationally and dispositionally to manage uncertainty and threat.” (p. 339).

In this paper, I examine the hypothesis that low cognitive ability may be related to conservative syndrome (or conservatism, for short) which, in turn, is defined in terms of measures of personality, social attitudes, values, and social norms. There are two ways to arrive at this assumption. First, we can assume that cognitive ability affects conservatism directly. Thus, the perceived threat may vary depending on cognitive level — sources of threat such as complexity, novelty, and ambiguity may be more threatening to those who score low as opposed to those who score high on cognitive tests. Second, we can postulate that there exists an independent process that influences both conservatism and cognitive functioning. A candidate for this role may be mental rigidity. My primary aim in this paper is to present evidence of correlation, not to test these two causal models. "