For 10 points, identify these market failures from economics, which occur when a third party not directly involved in a transaction is affected by it, which can be "positive" or "negative."
The "positional" variety of this concept occurs when new purchases change the context of evaluating another good. A theorem named for Coase states that in a system of zero transaction costs, the efficient outcome will be achieved regardless of property rights only if these effects are present. They can be corrected by issuing a Pigovian tax or subsidy, and an example of these phenomena which arises from common resources is known as the "Tragedy of the Commons." For 10 points, identify these market failures from economics, which occur when a third party not directly involved in a transaction is affected by it, which can be "positive" or "negative."
The "positional" variety of this concept occurs when new purchases change the context of evaluating another good.
{externalities}