The One Question to Ask Yourself When Facing a Moral Quandary

Psychologists offer a new perspective on moral reasoning.

Posted Nov 14, 2020

John Hain / Pixabay
Source: John Hain / Pixabay

We spend a lot of mental energy trying to decide what is right and what is wrong. And rightly so: The world would not be nearly as nice a place if humans didn't engage in the deep moral reasoning that they do.

But new research appearing in the Proceedings of the National Academy of Sciences suggests that there might be an easier way to discern right from wrong. It has to do with asking yourself one simple question: What would happen if everyone did that?

“Why not pick flowers for your home from the nice bushes in the public park? Why not take all of the money from the change jar at the checkout counter and buy yourself a chocolate? Why not flush a paper napkin down the toilet at work? To any of these questions, a person might reasonably respond: What if everybody did that?” state the authors of the research, led by Sydney Levine of Harvard University.

This type of moral reasoning, known as “universalism,” is one way to decide whether something is morally permissible. If the effects of many people engaging in an act are harmful, it should be viewed as unacceptable. If the effects of many people engaging in that act are harmless, it should be deemed acceptable.

And, it turns out that moral universalism yields more accurate predictions of real-world behavior than other theories in moral psychology. Consider this clever experiment from Levine’s paper: The researchers asked 1000 online respondents to consider a hypothetical scenario—whether it was acceptable for a vacationer at a lakeside village to use an advanced fishing hook. According to the scenario, there are 20 vacationers in this village who currently fish in a sustainable way with traditional fishing hooks. If fewer than three vacationers start using the advanced hook, there will be no negative consequences. If more than seven start using the hook, there will be a collapse of the fish population by the end of the season. Importantly, there is no rule against using the advanced fish hook in the community, and it is noted that all of the other vacationers have personally decided against using the advanced hook because they are worried about sustainability.

Is it morally permissible for this one vacationer to use the advanced hook? A rule-based view of moral reasoning would say that it is, since there is no rule stopping the vacationer from using the hook. An outcome-based view of moral reasoning would also suggest that using the advanced hook is morally permissable, given that all of the other fishermen have decided against using it and one person is not enough to negatively influence the "outcome" of the fish population.

Universalism, on the other hand, suggests that people should make their determination based on the number of people interested in using the advanced hook, which is exactly what the researchers found. When people were informed that none of the other vacationers were interested in using the advanced hook, approximately 75% of people said that it would be morally permissible for the one interested vacationer to use it. However, when they were informed that all of the other fishermen were interested in using the hook (even though they wouldn’t due to sustainability concerns), less than 50% of people judged it to be morally acceptable for the vacationer to use the advanced hook.

The researchers replicated their findings using other scenarios — foraging for mushrooms, hunting birds, trapping rabbits, and gathering clams — to ensure that their results weren’t an artifact of the fishing scenario itself. In each case, they found strong evidence for the moral universalism account of moral reasoning.

At a broader level, the authors believe there is one type of moral conundrum explained particularly well by moral universalism: threshold problems. “We define threshold problems by a basic structure: If only a few people do a particular action, nobody is harmed, but, when many people do it (i.e., more than the 'threshold' number), everyone is harmed,” state the researchers. “Because universalizing asks what happens when everyone abides by the same principles, it renders distinctive moral judgments in these cases.”

But they are also aware of the theory’s limitations. “We would not explain why it is wrong for one person to rob another, or drive on the left side of the road, by asking: What if everyone did that?” conclude the authors.


The logic of universalization guides moral judgment. Sydney Levine, Max Kleiman Weiner, Laura Schulz, Joshua Tenenbaum, Fiery Cushman. Proceedings of the National Academy of Sciences Oct 2020, 117 (42) 26158-26169