This article is more than 2 years old.

August 28, 2015 This article is more than 2 years old.

In my social psychology class, I pose an extra credit question where students choose between having two points or six points added onto their final term paper grade, with the stipulation that if more than 10% of the class chooses six points, no one gets any points.

This exercise is a classroom demonstration of the commons dilemma, and similar to the prisoner’s dilemma. Essentially, people are forced to choose between what would maximize their personal outcomes (more points) and what would be best for the group as a whole (fewer points).

It’s worth noting that this exercise was developed 25 years ago. I first learned it from my college psychology professor Steve Drigotas over a decade ago. I have been using it since 2008.

But recently, after a student of mine tweeted the dilemma of the extra credit question, it went viral in a way that I had never expected. So why is it only now starting to resonate with so many people worldwide? And why are people connecting this exercise to concerns about greed or selfishness?

The prisoner’s dilemma

Let’s analyze this class exercise. At first glance, it would seem that the obvious choice would be to pick two points—for then, everyone is sure to get the points.

But this requires a great deal of social trust. And that is not always apparent between strangers.

This exercise is analogous to real-world behavior involving consumption of public resources.

Thus, some students choose six points (greater than 10% of students in all of my classes have done so, except one class which hit 10% exactly). In fact, I would argue, picking six is a “rational” choice, because the likelihood of your own choice directly affecting the group is very small.

Now let’s look at the big picture.

Imagine if everyone in a group uses this line of “rational” reasoning. Then everyone would proceed to behave in a way that maximizes their own lot. The point here is that choosing six is “rational,” but only when we consider how individual actions impact the group.

In the aggregate, when thousands (or millions) of people behave this way, the consequences are disastrous.

This exercise is analogous to real-world behavior involving consumption of public resources (water, food, oil, electricity, etc). The “rational” mindset is how we end up with overharvesting, water or food shortages, pollution, climate change, etc.

What the exercise revealed

It’s important to note that most students in my class (around 80% each semester) end up choosing two points. While many students choose the “rational” six-point option, they are still in the minority.

I believe this is because most people do understand the importance of being communal. In other words, most people are happy to behave in a way that benefits others around them.

Here’s a real-world example at work: Honest Tea gave people the opportunity to pay for tea using the “honor system.” People can choose to take a bottle of tea without paying (the selfish option), or voluntarily pay for their tea by putting money into a jar (the communal option).

Again, the “rational” choice is to take the tea without paying. But a majority of people pay for their tea, even if they don’t have to.

Why is it so? Humans are prosocial creatures—which means they like to help each other.

That most students chose the prosocial option in my class is notable. It inspires me and gives me hope for the future. However, the fight is not over, and we still need to reduce excessive consumption.

People crave reciprocity

So, learning from this exercise, how can we increase cooperation on a mass scale?

Psychological science may provide some potential solutions.

One of the biggest theoretical developments in moral psychology in recent years has been Moral Foundations Theory, which suggests that there are several intuitive systems that feed into our judgments of right and wrong.

TheArches/Flickr, CC-BY-4.0 Everyone benefits when humans behave in ways that help others around them.

One of these is a concern about fairness/cheating.

People crave reciprocity with others. If someone does us a favor, we feel compelled to repay the kindness: or if they hurt us, we crave revenge.

Fairness manifests in justice and equality (eg, right to a fair trial), and in principles like the “Golden Rule” (treating people the same way you want them to treat you).

Another moral virtue is in-group loyalty.

Every community and nation has important symbols of unity (eg, the national flag), songs, pledges of allegiance, legends and monuments to its founders, sacred documents (eg, the Constitution), and institutions designed for the group’s protection (eg, the military).

In recent history, liberals have tended to strongly emphasize the importance of fairness and justice in building a strong society.

Consider the equal rights movements for African Americans, women, and LGBTQ folks, especially in light of the recent Supreme Court ruling. Liberals are fighting to close wage gaps, end discrimination and promote equal rights.

In contrast, conservatives have tended to emphasize the importance of group loyalty. Consider the emphasis on keeping America strong, protecting the homeland from foreign threats, bolstering the military and respecting national symbols like the flag.

Challenges outside the classroom

So how do these moral virtues apply to the commons dilemma game?

Well, if you want the extra points, you’re relying on other people to cooperate. So, think about the ethic of fairness.

If you want your group (eg, your school, your community) to thrive, you must personally contribute.

Pick the same choice that you would want others to take. Let your own desires for others’ behavior guide your own personal decisions—if you want others to choose two points, you should do the same.

Additionally, if you want your group (eg, your school, your community) to thrive, you must personally contribute. If you care about the health and the spirit of your culture, that sentiment must be reflected in your own actions.

If we consider the ethic of group loyalty, then choosing two points is not only cooperative, it’s patriotic. Making a conscious effort to limit one’s consumption of resources (by using less water, for example) is a duty to the flags, symbols and pledges of allegiance that unite us.

Outside of the classroom setting, there are environmental problems that must be solved, and there are moral virtues that can help bridge across the ideological aisle.

While liberals and conservatives may differ in their perspectives on political issues, there are ways to build common ground by drawing on their respective moral concerns.

Solving the world’s problems

Fairness and loyalty are two different paths toward reining in selfishness and making cooperation more possible.

If we can harness the power of these moral virtues together, we just might have a shot at solving some of the world’s toughest ecological problems.

A case in point is the Pentagon. Usually in charge of military matter, it now considers climate change a national security threat.

In order to combat climate change, we need to use all the tools available in our moral toolkit. Everyone must sacrifice for the common good of preserving our great nation, and it is essential that we view our neighbors as equal partners in this endeavor.

This post originally appeared at The Conversation. Follow @US_conversation on Twitter. We welcome your comments at ideas@qz.com.

Image by Nicole Yeary on Flickr, licensed under CC-BY-2.0.