Recently, a friend and colleague posted a Live Science article on Facebook that suggested atheists are more intelligent than religious believers, and soon I was drawn into one of those sticky internet conversations that rarely work out well. The article was based on a 2013 meta-analysis of sixty-three studies of the relationship of religious belief to intelligence, and the authors found a “significant negative association between intelligence and religiosity” (Zuckerman et al. 2013, 325). To their credit, my secular colleagues reacted with skepticism toward the article’s conclusion and pointed to friends and coworkers they knew who were both religious and very intelligent. Skepticism that is potentially against self-interest is particularly admirable, but as I quickly pointed out—while trying not to be too annoying—anecdotes are a weak form of evidence. For obvious reasons, this is a fraught area, but after coming across some recent research that sheds light on the topic, I have rashly decided to wade back in.
I should begin by acknowledging that any discussion of intelligence or IQ is going to be difficult. There are disputes about racial differences, sex differences, whether there are multiple intelligences, and whether the concept of intelligence is meaningful at all. Finally, there is a tendency among many people to essentialize IQ, making it a quantity that is fixed at birth and immutable. This is decidedly not the case. The so-called Flynn Effect, discovered by intelligence researcher James Flynn, showed a pattern of increasing intelligence scores over generations that could not be explained by genetics, and subsequent research has shown that educational interventions can produce substantial increases in IQ (Shenk 2017; Skuy et al. 2002). All of this leads to questions about what we are talking about when we talk about intelligence.
Researchers continue to be interested in intelligence test scores because they are related to a number of life outcomes, such as educational attainment, occupational status, and income (Ceci and Williams 1997; Spinks et al. 2007), and as the Live Science article suggests, the general public is also interested in intelligence and continues to use the construct in everyday conversation (e.g., “Aunt Rachel is really smart!”). So, having briefly laid out the caveats, let’s return to religion.
Two Stories about the Psychology of Religious Belief
There are actually two important findings in the psychology of religion that we should look at together. First, as suggested by the Live Science article, there is evidence that, on average, atheists and agnostics are more intelligent than religious people. Second, one of the most robust findings in the psychology of religion suggests that religious people are happier than nonreligious people.
The Intelligent Atheist
First, the story that launched this column: the relationship between religious belief and intelligence. There is a fairly long history of research on this question, particularly in recent years, and, in general, the results are consistent. A 2009 study assessed religiosity and average intelligence at the national level for 137 countries and found a substantial correlation between average intelligence and disbelief in a god (Lynn et al. 2009). This study must be taken with a big grain of salt because the intelligence measures were developed for use with Europeans and may not have been appropriate for other countries. One interesting finding of this study was that the United States was an outlier because it had an unusually low level of disbelief in god (10.5 percent) for a relatively high intelligence country.
A methodologically stronger study looked at the fifty U.S. states and found a substantial negative correlation between the average intelligence and average religiosity of a state (Pesta et al. 2010). Finally, the 2013 meta-analysis mentioned above combined the findings of sixty-three studies and also found a negative relationship (Zuckerman et al. 2013). The studies included in the meta-analysis were mostly from western countries, and as a result, the findings are limited to that region of the world. In addition, although the relationship is statistically significant (i.e., not due to chance), it is not very strong. In other words, if you tried to use a person’s IQ to predict their level of religiosity, it would not do a very good job—which explains why we all know many very intelligent religious people.
Although the evidence for this relationship is fairly reliable, as you might imagine, it has not gone undisputed. In a recent article, researchers from Australia, the United Kingdom, the Netherlands, and Sweden (Dutton et al. 2019) reanalyzed data from previous studies and suggested that the negative relationship between intelligence and religiosity was not a function of g, a general form of intelligence, but was instead produced by more specific forms of intelligence (e.g., vocabulary, spatial relations, etc.). Unfortunately for the two samples they studied, the relationships with specific intelligences were not consistent with each other, making it difficult to draw a clear conclusion. The authors went on to make the surprising speculation that the relationship between intelligence and religiosity is produced by autistic symptoms—a claim that, in my view, needs much stronger evidence. In any case, their research does little to alter the overall picture. On average, people who are nonbelievers are slightly more intelligent than believers.
There are a number of hypotheses about why intelligence might be related to religious belief. For example, one proposal is that atheism is a form of nonconformity. In many communities, religious belief would be a conformist choice, and there is empirical evidence that intelligent people are less likely conform (Rhodes and Wood 1992).
Another theory suggests that nonreligious people use more analytical thinking, which is also related to intelligence. According to the popular dual process theory of cognition, we employ two reasoning systems: System 1, which is quick and intuitive, and System 2, which is slower, more deliberative, and capable of analytical reasoning and calculation (Kahneman 2011). Researchers have developed a short test to measure analytical reasoning called the Cognitive Reflection Test (CRT; Frederick 2005). It has just three questions:
- A bat and a ball cost $1.10 in total. The bat costs $1.00 more than the ball. How much does the ball cost? _____ cents.
- If it takes 5 machines 5 minutes to make 5 widgets, how long would it take 100 machines to make 100 widgets? _____ minutes.
- In a lake, there is a patch of lily pads. Every day, the patch doubles in size. If it takes 48 days for the patch to cover the entire lake, how long would it take for the patch to cover half of the lake? _____ days.
For most people, the CRT can be mastered only by engaging the slower but more powerful machinery of System 2 and cannot be solved using the simple intuitive heuristics of System 1. (By the way, the answers to the CRT are five cents, five minutes, and forty-seven days.)
A long series of studies has shown that atheists score better on tests of analytical reasoning. For example, psychologist Gordon Pennycook and colleagues recently reported the results of four new experiments testing this effect and also conducted a meta-analysis of thirty-one studies (including the four new ones) and found a consistent relationship of higher scores on analytic reasoning among agnostics and atheists (Pennycook et al. 2016). However, it is important to remember that, similar to the studies of intelligence and religious belief, this relationship was statistically significant but not very large in a practical sense. Other factors must contribute to religious belief or nonbelief, and there are many religious people who use more analytical reasoning.
The Happy Believer
More research is needed to understand the relationship between intelligence and nonbelief, but in an effort to provide a balanced picture, I feel compelled to mention the other consistent relationship with religious belief: happiness. Lest nonbelievers become smug, there is a substantial body of research showing that religious people are happier than nonreligious people (Diener and Biswas-Diener 2008). For example, a study based on the European Social Survey for the years 2000 to 2008 measured happiness by asking the question, “Taking all things together, how happy would you say you are?” (Fidrmuc and Tunalı 2015). Survey respondents answered on a scale from 0 “extremely unhappy” to ten “extremely happy.” Because the survey also recorded many demographic questions, the researchers were able to duplicate a number of findings observed in previous studies, including that men were generally less happy than women and that higher education was associated with greater happiness even when the effects of income and employment status were controlled. In addition, married couples were happier than unmarrieds, and rural people were happier than urban. Past research has shown that adults with children have lower happiness levels than adults without children, and consistent with this finding, the European study showed that middle aged people were less happy on average than either younger or older adults. Finally, after controlling for many other variables, the researchers found that Europeans who held religious or spiritual beliefs were happier than those who did not.
Sometimes investigators find that aggregate results at the level of a state or a country conflict with those at the level of the individual, and this vexing situation applies to studies of religious engagement. For example, U.S, states with higher religious engagement have higher crime rates, but when measured at the level of the individual, higher religious engagement is associated with lower crime rates (Myers and Diener 2018, 221). Go figure. This kind of paradoxical pattern of aggregate and individual results holds for the relationship of religion with a number of negative social variables, such as smoking, teen pregnancy, and life expectancy—leading one pair of researchers to ask, “Why might there be this sharp contradiction between religious people being happy and healthy, and religious places being anything but?” (Deaton and Stone 2013, 595).
A similar paradox is found in the case of religion and the positive variable—happiness. A study of religious engagement among 152 countries found that higher religious engagement was associated with lower levels of happiness (Myers and Diener 2018, 222), but a U.S. study of 57,000 respondents to the General Social Survey of the National Opinion Research Center showed a consistent increasing percentage of happy people with higher levels of religious engagement (See Figure 1).
So, according to the evidence, atheism appears to be a choice to be sadder but wiser, but, in fact, we are not justified in drawing that conclusion. It is important to recognize that all the evidence cited in this column is correlational, which means we cannot identify what causes any of these relationships—only that certain variables travel together. In the case of intelligence and religious belief, it seems more likely that intelligence pulls people away from religion rather than religion or atheism influencing level of intelligence. But we cannot know this for certain because there could be some third thing that we have not identified that controls both intelligence and religious belief.
In the case of religion and happiness, the causal arrow is even more difficult to draw. Are happy people attracted to religion, or does religious engagement make people happier? Or is it some unknown third thing that makes people both happier and more religious—or the reverse? These are complicated questions that we are not able to answer yet. The clearest thing we can say is that whether you choose atheism or religion, the outcome will be a mixed blessing.
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