The Tragedy of the Commons

There's a theory that explains how it is that a society, and that includes larger ones such as a nation, and smaller ones, such as a condominium association, sometimes decay and fall into ruin. It's called the "tragedy of the commons." This theory was first put forth by Garrett Hardin in 1968. Here is an explanation by game theorist Ken Binmore:

Critics ask how can it possibly be rational for a society to engineer its own ruin. Can't we see that everybody would be better off if everybody were to grab less of the common resource? The error in such reasoning is elementary. A player in the human game of life isn't some abstract entity called "everybody." We are all separate individuals, each with our own aims and purposes. Even when our capacity for love moves us to make sacrifices for others, we each do so in our own way and for our own reasons. If we pretend otherwise, we have no hope of ever getting to grips with the Tragedy of the Commons.

So that is an explanation of how the actions of individuals can be at cross-purposes to that of the group, and the result can be disaster for the group, and ultimately the individual.