Filosofen David Lewis ger ett exempel på vad han menar med en konvention och hur de kan ha sitt ursprung i en överenskommelse:
If four men who camp together find that often they waste effort by covering the same ground in search of firewood, they may get fed up and agree once and for all: let Morgan look to the north, Jones to the east, Owen to the south, Griffith to the west. From that day on, each goes his proper way without further discussion. A regularity has begun by explicit agreement. At first, perhaps, it persists because each man feels bound by his promise and takes no account of the advantages of keeping it or breaking it. But years pass. They forget that they agreed. Morgan is replaced by Thomas, who never heard of the agreement and never promised anything. Yet whenever they need firewood each still goes off in his proper direction, because he knows that is how to have the ground to himself. As the force of their original promises fades away, the regularity in their behavior becomes a convention.
Lewis, David. (2002) Convention. A Philosophical Study, Oxford: Blackwell Publishers, s 45.