According to political scientist Robert Putnam, successful democracies rely on strong social networks. In his 1993 book Making Democracy Work: Civic Traditions In Modern Italy, Putnam analyzes the regional governments of Italy, positing that prosperous institutions have strong social networks, whereas less successful institutions have weak social networks. Strong social networks, he reasons, promote trust between citizens, thus strengthening the democracy.

Now, a more recently published research article by Noah Carl and Francesco C. Billari (both affiliated with the University of Oxford) builds upon Putnam’s theory, citing evidence that individuals who place more trust in the general public are more likely to start a business, perform volunteer work, and report better physical health and overall happiness.

With that in mind, Carl and Billari specify that trust can be broken down into either one of two categories: generalized or particularized. Particularized trust refers to the trust we place in close friends and family members, while generalized trust refers to the level of trust we place in fellow citizens. It is the latter specification that has been linked to economic success, better physical and mental health and, perhaps most interestingly, higher intelligence.

To identify the link between trust and intellect, Carl and Billari analyzed results from the General Social Survey (GSS), a public opinion survey administered to a nationally representative sample of US adults every one to two years. The first component of the test was a ten-word vocabulary test that is noted to have a 0.71 correlation with the Army General Classification Test, an IQ exam developed by the US military. In addition, surveyors rated how well participants understood the survey questions. Participants’ generalized trust ratings were measured by the question, “Generally speaking, would you say that most people can be trusted or that you can’t be too careful in dealing with people?” The respondent could pick one of three answer choices: can trust, cannot trust or it depends.

According to Carl and Billari’s findings, those who scored well on verbal ability were 34 percent more likely to trust an individual than those who scored lower. The findings also indicate a positive correlation between generalized trust and question comprehension, with an individual who exhibited a favorable understanding being 11 percent more likely to trust others than an individual who showed a poor understanding of the questions.

In their conclusion, Carl and Billari reaffirm that the link between generalized trust and intellect “supports the hypothesis that being able to evaluate someone’s quality as a trading partner is a distinct component of human intelligence, which evolved through natural selection.” They point out that more research is needed to determine the exact nature of the link and posit that future research should evaluate the mechanisms by which generalized trust enhances health and well-being.

Did You Know?

The General Social Survey (GSS) is considered the single best source on societal trends. Many of the questions on the survey have remained unchanged in over four decades “to facilitate time-trend studies as well as replication of earlier findings.” Topics covered include civil liberties, intergroup tolerance, morality, national spending priorities, psychological well-being and social mobility.