The Symmetry of Rival and Anti-Rival Goods

A shoveled sidewalk is a strange sort of common pool resource: it’s not like fisheries or irrigation where the more one person uses the resource, the less there is for others. That is, it’s not precisely “rivalrous,” one of two conditions required for a common-pool resource to flourish. In fact, the more people shovel their sidewalks, the better off each individual with a shoveled sidewalk is. This is what economists call “anti-rivalry” and is frequently linked to network effects.