There’s no such thing as common sense

There are certain statements that we consider to be obviously true, even though we may not be able to explain why. This is what we refer to as common sense — what all sensible people know. However, even common sense sayings often reveal that common sense is not so common. A recently published study in PNAS scientific journal aimed to quantify common sense, both on an individual level and for society as a whole. The study surveyed 2,000 participants assessing 4,400 statements, and found that an entire society does not share a common sense.

“Our findings suggest that there tends to be a reasonable amount of common sense between two people. However, as a society, there is a lack of widespread common sense shared by everyone,” said the University of Pennsylvania’s Mark Whiting, a co-author of the study. Whiting says individuals often find points of agreement with others they regularly interact with, but they don’t realize that there are few things that everyone universally agrees on.

The survey included questions aimed at understanding the extent to which common sense is shared. It covered knowledge like “triangles have three sides,” experiential learning such as “a battery doesn’t provide energy forever,” and moral statements like “all human beings are created equal.” The results revealed that statements about physical reality like the sun will rise tomorrow, were more commonly shared than ideas about how things should be, like equal opportunity in education. Pithy truisms and aphorisms were not often regarded as common sense.

Javier Vilanova, a philosophy professor at the Complutense University of Madrid, said “the true beauty of common sense lies not in the description one makes of a situation, but in the actions that follow.” That’s why he thinks conducting an experiment to observe people’s actions, rather than just their ideas about certain statements, can provide a more accurate evaluation of what is shared and what isn’t. “Common sense is best observed and cultivated through everyday life experiences,” said Vilanova, who uses the example of money to illustrate how its value is derived from a collective belief.

The study found that demographic factors like gender, income level and political preferences were not linked to common sense. However, they used two tests to discover correlations: one to evaluate a person’s ability to override one’s instincts (the cognitive reflection test), and another to assesses the ability to recognize and understand another person’s mental state (the “reading the mind in the eyes” test). Vilanova suggests that the absence of social or gender differences highlights how common sense unites people in diverse groups through a shared understanding.

The PNAS study aimed to address the challenge of defining common sense, which often serves as a means of establishing authority but is difficult to pin down. To accomplish this, participants were asked to identify what they consider meaningful and shared by others, going beyond the typical perception of common sense. When someone disagrees with our notion of common sense, we tend to assume that they are simply mistaken. The authors of the study hope that the tool they created can be used to study common sense in different contexts to determine if and how it has changed over time, and to reveal cultural differences. They plan to study if political statements are framed worse in common sense than in everyday life or if their use in political rhetoric degrades the term in the public’s eyes.

Throughout history, our understanding of common sense has evolved, partly due to scientific advancements. Science seeks to uncover the reality beneath our deeply ingrained perceptions. Not long ago, it seemed more intuitive to believe that the Earth is flat and stationary. However, through rational observation, we now know it is a sphere that orbits the Sun at over 67,000 miles per hour (100,000 kph). Common sense serves as a crucial starting point for social relationships and scientific communication. Yet, despite its name, common sense is often inherently unique to each individual.

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