The Eye of Providence, or the all-seeing eye of God, seen here on the $1 bill, has been taken by some to be evidence of a conspiracy involving the founders of the United States. (Photo: Wikimedia Commons)

A few years back, I was startled and dismayed when, over lunch, a friend told me he had come to believe that the 9/11 attacks were "an inside job." This highly intelligent and accomplished man was convinced that the official explanation of that day's terrorist attacks was a hoax. No amount of evidence to the contrary could convince him otherwise.

How did this happen? It's impossible to say for certain, but he is far from alone: A 2014 study concluded that half of Americans believe at least one conspiracy theory. There has been plenty of research in recent years attempting to discover what leads people to trust in these often-outlandish, highly problematic narratives. While the results suggest the answer is not simple, a newly published paper provides some valuable insights.

The research looks at two elements that have been cited as playing a role in conspiracy beliefs: unstable self-esteem (the uncomfortable state of feeling unsure about one's abilities, attitudes, or value to society), and a strong sense of belongingness (which leads to intense identification with some social group). The study finds that these two factors are indeed strong predictors of such a mindset—when they interact in a specific way.

Participants who were feeling uncertain about themselves "experienced stronger conspiracy beliefs following messages of inclusion, as opposed to exclusion."

The self-uncertainty inspires a strong desire to make sense of an often-random world; the feeling of solidarity means you want to protect not only yourself, but "your people," from outside menace. Put these elements together, and you get not garden-variety paranoia ("He is out to get me"), but rather its larger-scale version ("They are out to get us").

Psychologist Jan-Willem van Prooijen offers this hybrid theory in the European Journal of Social Psychology. He describes two experiments that provide evidence backing up his assertion.

In the first, the participants—84 university undergraduates—began by responding to a series of statements designed to measure their overall level of self-esteem, and the extent to which it fluctuates from day to day.

They were then asked to imagine themselves two decades into the future. Half were instructed to envision "a future where they had a long and lasting relationship" and plenty of friends. The others imagined "a future where their life partner had left them years earlier," and their friends had deserted them.

Finally, participants were asked to complete a purportedly unrelated study of their views on world events—specifically, climate change, and the NATO intervention in Libya. They were asked conspiracy-related questions such as "To what extent do you believe NATO has a hidden agenda," and "Do you believe governments deliberately withhold information about global warming?"

The researchers report that thoughts of strong social connection "led to stronger conspiracy beliefs ... but only among people who score high on self-uncertainty."

For the second study, 81 undergraduates were asked "to remember a situation in their own life where they felt really certain, or uncertain, about themselves." After undergoing the same manipulation (which created feelings of isolation or belongingness), they were asked conspiracy-related questions about the activities of the major oil companies, as well as the 2008 financial crisis.

The results were the same: Participants who were feeling uncertain about themselves "experienced stronger conspiracy beliefs following messages of inclusion, as opposed to exclusion."

So the cliche of the conspiracy theorist as an isolated individual who has spent too much time in solitary rumination appears to be mistaken. Rather, these results "suggest that conspiracy beliefs actually emerge from social motives—namely, a genuine concern for other people that are victimized, endangered, deceived, or otherwise threatened," van Prooijen writes.

"It can be concluded that sometimes—that is, when experiencing self-uncertainty—feelings of inclusion breed suspicion."

Findings is a daily column by Pacific Standard staff writer Tom Jacobs, who scours the psychological-research journals to discover new insights into human behavior, ranging from the origins of our political beliefs to the cultivation of creativity.