An out-of-control trolley car is speeding toward a group of five people. By pressing a button, you can switch the trolley to another track where one person stands. Do you allow the trolley to continue as is or do you press the button so that it hits and kills just one person instead of five?

It turns out your answer is crucial to how popular you will be, researchers behind a new study say. People who uphold moral absolutes — “killing is always wrong, no matter what the consequences” — are also considered more trustworthy, a person you want in your life and in your posse.

The Oxford and Cornell study examines two schools of moral thought. Consequentialist theories say we should always aim to maximize the greatest good for the greatest number of people, even if this means causing some harm: in this case, killing one person in order to save five. By contrast, deontological theories focus on moral rules, rights, and duties. This approach describes certain actions as wrong — and always wrong — no matter the consequences, even when more lives might be lost, as in the example of the trolley.

When making snap judgments, most of us default to the latter style of morality, the researchers say. While psychologists argue our commonly shared trust in absolutes is based on irrational and emotional responses, the researchers wondered if instead these rules may have been coded into our human nature by evolutionary pressures? So, they designed a study where they presented life-or-death situations and next asked volunteers to make a few quick decisions. Then, they asked who they would prefer as partners — the people who made rule-based moral judgments or those who weighed costs and benefits?

A Tale of Two Soldiers

Harry is the leader of a small group of soldiers who are out of ammunition and returning from a completed mission deep in enemy territory. One of his men steps in a trap from which it is impossible to free him. The soldier is badly injured, the enemy is advancing. Undoubtedly, when the soldier is found, the enemy will torture him to death. Unable to remain beside the trap any longer, Harry offers to stab the soldier in the heart after he's unconscious to kill him quickly and prevent him from suffering at the hands of the torturers. Just before he passes out, the soldier makes a plea.

After describing this scenario, the researchers told some participants that the soldier said, “Please, kill me. I don't want to suffer at the hands of torturers,” while others heard, “Please, don't kill me. I don't want to die out here in the field.”

“When participants read that the soldier wanted to be killed, 88 percent indicated that they thought it morally right to stab the soldier, with this dropping to 44 percent for participants who read that the soldier asked not to be killed,” wrote the researchers, who note participants here wrestled with two lines of reasoning: “killing is wrong” versus “honor people’s autonomy and respect their wishes.”

The results help explain why those people who stick to moral rules appear more popular than others, says the research team. It’s not because they are uptight sticklers but because the moral laws emphasize the importance of respecting the wishes and desires of others.

In fact, across nine total experiments involving more than 2,400 participants, the researchers discovered that people who approached both the soldier and trolley car dilemmas with absolute morality were considered more trustworthy than people who endorsed a consequentialist approach.

Specifically, when asked to trust another person with their money, participants handed over more cash (and felt more confident about getting it back) to those who refused to sacrifice one to save many. This result makes perfect sense, as the researchers point out, since most of us do not warm to the idea of our own loved ones doing a cost/benefit analysis of whether we might be sacrificed for the good of the many.

And so, the Darwinian logic unspools. If people who stick to absolutes are the preferred partners, they will be selected more frequently than others, and over time, this social adaptation will become more common in the overall population.

One final note: Even the people who themselves favored the greater good chose the absolutists over those with views similar to their own. Apparently no one wants to be with someone who calculates on behalf of the crowd instead of honoring the vulnerable individual.

Source: Everett JAC, Pizarro D, Crockett MJ. Inference of Trustworthiness From Intuitive Moral Judgments. Journal of Experimental Psychology. 2016.