Economists fondly call it an externality. What’s an externality? It’s what happens when someone takes an action but someone else, without agreeing, pays some or all the costs of that action. An externality is an economic version of taxation without representation. If you happen to live downwind from a fertilizer factory, the ammonium stench is an externality.
–Steven D. Levitt, Stephen J. Dubner, SuperFreakonomics
