Tragedy of Commons. An example.

Many hundreds of years ago, somewhere in central India, lived a king who ruled a small but peaceful kingdom. Things were going well, as they had always done, until all of a sudden and for no good reason, things stopped going so well.

There were fires in the central granary one month and the rains failed in the next. The farmers refused to pay their taxes and the princess eloped with the court astrologer. The townsfolk, in the capital city were faced with a fresh wave of crime and the public chariot services went on a strike. All this while grain prices were going up and you really had to struggle to make the ends meet. Get the picture?

The king realized that this called for emergency measures. He passed a decree that all the people living in the inner city were required to bring and pour a cup of milk each into the dry well  located behind the palace, on the next 'amavasya' night. He had been advised that by thus offering milk to the goddess of the land - who dwelt in the temple, adjoining the well - the goddess would be happy and things would be fine after that. PS: Now you know why the princess eloped with the astrologer :)

On amavasya night, throughout the night, there was a stream of people walking to the dry well. Everyone brought a cup along and poured into the dry well, as he chanted the goddess' name. The king watched from his palace and smiled happily.

Next morning when the king went to the well, he found to his surprise that the well - instead of being full of milk, was instead full of water. Everyone of his subjects had taken advantage of the dark amavasya night and believing that others will be pouring milk, had himself taken the liberty of pouring in water.

This is the tragedy of commons too. Whether it is the overtaking motorist who causes the traffic jam or the finicky housewife who keeps her own house spotless but throws the garbage out into the vacant plot nearby, because everyone else is doing the same. The tragedy is the same. 

So what is the way out?