Cooperation between groups is often undermined by self-interest or a group’s own sense of morality.

The world is changing rapidly, but humans are still biologically much the same. Evolution has given us the skills to cooperate within groups, but unfortunately, our ability to cooperate between groups still leaves much to be desired. The history of conflict is enough to tell us that.

Mutually beneficial cooperation is endangered by many things, but the clearest threat is what’s known as the tragedy of the commons.

This is fancy sociology speak for the conflict between self-interest and collective interest: in other words, Me Versus Us/ You.

Imagine that Art is journeying alone through the Wild West. He spots the silhouette of another traveler up ahead at a watering hole. Art isn’t sure whether the stranger is armed, but Art does have his pistols with him. They meet and size each other up as their horses drink at the watering hole.

If Art thinks selfishly, there’s little to be lost if he shoots Bud, the stranger. There’d be no chance of Art getting robbed, for starters. But let’s say that Art opts not to shoot Bud, for now. When Art later nods off, Bud spikes his whiskey with poison. Bud, you see, is also afraid of being robbed. When Art wakes, he changes his mind and shoots Bud dead. Then he unwittingly knocks back the poisoned whiskey and dies. If Art and Bud had been less self-interested and instead acted cooperatively, neither would have died. That’s the tragedy of the commons.

A second threat to mutually beneficial cooperation is known as the tragedy of commonsense morality. This time it’s a question of Us Versus Them. In other words, one group sets its own values against those of another.

An excellent example of this mentality is demonstrated by the story of the Danish political newspaper Jyllands-Posten. In response to the Islamic hadith forbidding visual depictions of the Prophet Muhammad, it published a series of cartoons satirizing Muhammad in 2005. The general climate was also important: there was an ongoing debate about journalists self-censoring their views on Islam.

Global media outlets followed the controversy. Before long, violent protests sprang up around the Muslim world. Over a hundred people were killed, and Danish embassies in Syria, Lebanon and Iran were set on fire.

The two groups – Danish journalists and Muslims – were each fighting for what they saw as commonsense morality. The journalists hated feeling censored, while Muslims didn’t want their religion disrespected. But the end result was conflict. This is how commonsense morality can lead to tragedy.