Peter DeScioli, above, has teamed up with colleagues to answer the question of why people tend to disagree, especially on issues of morality. The study, published on Oct. 29, is titled “Equality or equity? Moral judgments follow the money.”(PHOTO COURTESY OF PETER DESCIOLI)

A new study on moral disagreements and the human inclination towards self-interest was recently published in the research journal Proceedings of the Royal Society B. Peter DeScioli, an assistant professor at Stony Brook University’s Department of Political Science, came together with fellow colleagues in hopes of answering the ultimate question: why do people not only disagree, but disagree on issues of morality?

While looking through the lens of one common moral disagreement, equity versus equality, the team of five set out to provide an economically justified answer to this anomaly. Published on Oct. 29, the study, “Equity or equality? Moral judgments follow the money,” investigated the idea of the oft-undeniable moral disparities between ever competing humans.

DeScioli, who completed postdoctoral fellowships at multiple institutions, including Penn State, Chapman, Brandeis and Harvard, was one of the lead examiners in the study.

“I studied evolutionary psychology and did Ph.D. work on moral condemnation,” DeScioli said. “I started thinking about why people condemn others. Most studies pointed to cooperation as the overarching goal. This didn’t seem to give value, since [cooperation] doesn’t look like condemnation. For example, same sex marriage does not seem to be making society cooperative.”


Having taught numerous classes in psychology and politics, published a number of manuscripts and being invited to a handful of talks, DeScioli said he started thinking of alternative explanations for moral issues early on.

“I ended up thinking about how people choose sides in disparities,” he said, noting that based on their personalities, some people favor equity over equality. “A lot of previous research has shown biased reasoning that comes from personality–saying that disagreements are never due to self-interest, just basic values. We felt that people might be willing to change their moral values depending on their roles as ‘moral chameleons’.”

This idea of the ‘moral chameleon,’ he said, relates to personal disposition. He ended up teaming up with University of California Berkely’s Maxim Massenkoff, University of Chicago’s Alex Shaw, Aarhus University’s Michael Bang Petersen and University of Pennsylvania’s Robert Kurzban.

They created an economic game designed to highlight differences of opinion, based on amount of effort and profit involved.


“In any situation where people work together to do something, they have to make moral decisions,” DeScioli said. “It relates to the theory of morality and evolutionary perspective. We come from tens of thousands of years of moral values and have to selectively follow the society that helps us survive.”

A group of participants worked in pairs to “transcribe a paragraph for a cash reward,” according to the study. One member was considered the “Typist,” and transcribed three paragraphs, while the other was considered the “Checker,” and transcribed only one out of the three randomly selected paragraphs. Cash rewards were given if and when transcriptions of a given pair matched.

The Typist was responsible for the division of reward money. He or she was given the option of dividing the money evenly (50/50) following the principle of equality, or in proportion to the amount of work done (75/25) following the principle of equity.

“Most Typists in this situation took the larger share of the pie, consistent with self-interest,” the study authors wrote.

In the first experiment, 90 participants completed an eight-minute long online study, using Amazon’s Mechanical Turk website. Participants were randomly assigned roles, which were revealed after the designated tasks were completed.


A stunning 81 percent of Typists chose the equitable division over the equal division. It was deduced that “participants’ fairness and morality judgments depended on their role” and that “Typists judged the equitable division to be more fair.”

In the second experiment, participants made fairness and moral judgments about each other before being notified of their roles.

Seventy-two percent of Typists chose the equitable division over the equal one.

In the final test, the Typist and Checker were responsible for transcribing one paragraph each. The purpose here, was “to remove the Typist’s equity justification for choosing the 75%/25% division.”

Just 22 percent of Typists chose the self-interested unequal division.

“These experiments confirmed our suspicion that people have moral inclinations towards that which involves money/ self interest,” DeScioli said. “People not only prefer the rule that most benefits them, but also judge it to be more fair and moral.”


It was found that the views held by participants about equality and equity changed very quickly, once they learned where their interests lie.

“We find limits to self-interest, in that when the justification for equity is removed, participants no longer show strategic advocacy of the unequal division,” according to the study.

DeScioli stressed that the equity/equality issue is just one example of a moral disagreement, and that more or less of the same would apply to any moral disagreement.

The biggest suggestion DeScioli had to give was that people be a bit more self-critical about their moral opinions when disagreeing with others. He said that knowing we each have biases is fundamental in making compromises.

“Moral opinion and self interest isn’t exactly the same thing,” he said. “It is not true that people always go with their self-interest. Within that constraint, we have to strike a compromise.”


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