In Garrison Keillor’s Minnesota town of Lake Wobegon, “all the women are strong, all the men are good looking, and all the children are above average.” Though the town and its characters are fictional, part of the enduring appeal of the News from Lake Wobegon is the way that Keillor captures the human experience—right down to the fact that all the children are above average.

Indeed, decades of research confirm that we are all above average—at least in our own minds. When comparing ourselves versus other people, we tend to rate ourselves more highly on a host of positive measures, including intelligence, ambition, friendliness, and modesty (ha!). This finding is sometimes called the “self-enhancement” effect.

This self-enhancement effect is most profound for moral characteristics. While we generally cast ourselves in a positive light relative to our peers, above all else we believe that we are more just, more trustworthy, more moral than others. This self-righteousness can be destructive because it reduces our willingness to cooperate or compromise, creates distance between ourselves and others, and can lead to intolerance or even violence. Feelings of moral superiority may play a role in political discord, social conflict, and even terrorism.

Ben Tappin and Ryan McKay at the University of London wondered why people strongly believe they are virtuous and moral, yet simultaneously regard the average person as significantly less so. Tappin and McKay conducted a study in which participants considered 30 different character traits, including traits associated with morality (e.g., sincerity, honesty), sociability (e.g., warmth, likeability), and agency (e.g., competence, creativity). Participants rated the extent to which each trait described themselves, described the average person, and was socially desirable. They then used some clever reasoning to tease out how irrational it was for people to think of themselves as better than average in each of these categories. We are most irrational, they found, when we consider moral traits.

How did they determine how rational people were being? Tappin and McKay point out that some degree of self-enhancement is actually rational. When we make judgments about ourselves and others, we have far more information about our own actions and behaviors than we do about the average person. It makes sense, then, that we are more cautious—or less extreme—in our evaluations of others relative to ourselves.

They key to estimating the rational component of self-enhancement is understanding how an individual might infer the characteristics of others. To do this, Tappin and McKay adapted the Social Projection Index (SPI). This measure recognizes that statistically, most people are in the majority most of the time, so to make accurate judgments about others we should, to some extent, project what we know about ourselves. Of course the extent of that projection will vary: it depends on how unusual a person truly is. People are rational, the authors argue, when they accurately perceive how similar they are to the average person, and make use of that. In other words, if you are very similar to other people, your ratings of others should be similar to how you rate yourself. But if you are truly different from other people, you can be more justified in giving others different ratings than you give yourself.

To illustrate, consider the following example. Let’s say Jane’s ratings of herself are very similar to the average of the self-ratings made by others. She is fairly typical. In her case, it would be rational for her to assume that others have similar ratings to her own. And, conversely, it would be irrational for her to assume that she is better than others. Let’s say that Jack, on the other hand, rates himself in ways that are atypical of the average of the self-ratings made by others. He is objectively unusual. In his case, it would be more rational for him to assume that he is better than others in some way.

Of course one challenge in making rational self-evaluations is knowing how typical (or atypical) you truly are. For any individual person, it’s a guess. You may know yourself well, but you may overestimate or underestimate how alike others you are. Tappin and McKay, however, were able to measure individuals’ typicality more precisely using the responses from their experiment. First, they calculated the profile of the “typical Joe” by averaging the self-evaluation ratings for all participants. Then, for each participant, they evaluated the extent to which individual self-ratings aligned with those of the “typical Joe,” a measure known as the “coefficient of similarity.” Those with a high coefficient of similarity (like Jane) would be expected to have similar ratings for self and others, while those with a low coefficient of similarity (like Jack) would be expected to have less similar ratings for self and others. For each participant, Tappin and McKay used the coefficient of similarity to compute inferred self-judgments—how participants should have rated themselves if their ratings were rational.

Tappin and McKay not only considered the discrepancy between actual self-ratings and inferred self-ratings; they also considered the extent to which these ratings were differentially affected by trait desirability. Irrational thinking is revealed when trait desirability more accurately predicts actual self-ratings than inferred self-ratings. In other words, you are irrational when you consider a trait highly appealing, and you let that appeal influence your self-ratings in such a way that you distort the similarity between yourself and others.

Tappin and McKay found that the irrational component of the self-enhancement effect was greater for morality traits than either agency or sociability traits. Participants were least likely to accurately use their self-judgments in projecting other-judgments when considering morality traits, and trait desirability predicted actual self-judgments of morality to a much greater extent than it predicted inferred self-judgments of morality.

So we believe ourselves to be more moral than others, and we make these judgments irrationally. What are the consequences? On the plus side, feelings of moral superiority could, in theory, protect our well-being. For example, there is danger in mistakenly believing that people are more trustworthy or loyal than they really are, and approaching others with moral skepticism may reduce the likelihood that we fall prey to a liar or a cheat. On the other hand, self-enhanced moral superiority could erode our own ethical behavior. Evidence from related studies suggests that self-perceptions of morality may “license” future immoral actions. An individual who volunteers to deliver food for Meals on Wheels, for example, may later find it acceptable to take home office supplies from work. This moral licensing effect has been documented in many domains, including consumer behavior, the workplace, race relations, and charitable donations. When our moral self-image is well-established (either through actions or the self-enhancement effect), we may feel less obligated to follow a strict ethical code. Thus, the fact that we tend to believe that we are above the moral average could ironically makes us less so.

Cindi May is a Professor of Psychology at the College of Charleston. She explores avenues for improving cognitive function in college students, older adults, and individuals with intellectual disabilities. She also works to promote the inclusion of students with intellectual disabilities in classrooms with their non-disabled peers from kindergarten through college.