Suppose that some one in a group starts taking more from a common resource than is allowed. What does this do to the resource? If the rule-breaker is not stopped by the rest of the group he or she will inspire imitators and quickly people will cheat and undermine the agreement, as more people see a small group taking more than their allotted share and they start cheating too. Soon the common resource is depleted and becomes less available or it goes extinct. This process is often called the tragedy of the commons. But commons have some history of being wisely regulated by group agreements, as the Nobel Prize economist Elinor Ostrom has shown.
Civility is a common pool resource. Civility allows the people of any group to get along with each other. It makes civilization possible. Civility allows us to have all these interactions between strangers, between coworkers, between different levels of hierarchies, between employees and members of the public at large, all in ways that avoid intimidation and violence.
When civility breaks down, it destroys cooperation; and it needs to be quickly repaired or else it can corrode society from the inside, because it creates a poisonous atmosphere where no one appears trustworthy, more people become permanently hostile, and the level of violence increases. Needless to say, the absence of civility hurts productivity in many different ways.
When our leaders display incivility this one of the worst kinds of erosion of a public good. The leader sets an example. If he or she is allowed to get away with incivility, many others will be inspired to do the same, radically lowering the level of civility in all of society.
What about protest movements? Aren't these a form of incivility? In the sixties, the civil rights movement was protesting against institutional discrimination and the absence of civil rights for blacks. A movement like Civil Rights can seem disruptive to a significant number of people, often because they may have benefited from the discrimination in the first place. If the rules as they are enforced are manifestly unfair, the apparent civility may be a sham, existing only by virtue of physical force and intimidation.
In contrast, attacks on political correctness, although seemingly legitimate complaints, are not objections to unfair rules, they can often be attempts to restigmatize and remarginalize previously disadvantaged groups. These attacks are contributions to a larger agenda of strengthening formerly dominant groups by attacking the weak and formerly oppressed groups - the modus operandi of Fascism.
Civility is a common pool resource. it makes it possible for the participants of every human group to share information, to arbitrate disputes without leading to violence, to have fair exchange, and to facilitate mutual help in times of need. We are in trouble when we start to lose civility. Remember, it is a common pool resource. What that means in practice is that the pool of civility can be depleted if enough people trample on the rules. When civility is eroded it is far more difficult for a group to regain it than it would have been to maintain it in the first place, and that is because it is a common pool resource.