The inefficiency of markets. Criteria for rationing goods and resources must be established because of scarcity. The means by which we organize our understanding of economic relationships is Economic theory. Rational economic thought. Conventionalism The opportunity cost of an action is the monetary payment the action required.
Scarce goods are priceless.
Incentives matter - if the personal cost of a choice increases, individuals will be less likely to choose it. The realism of the assumptions is the best test of an economic theory. When deciding how to allocate time, the concept of opportunity cost is meaningless. When deciding whether to purchase a second order of Cheese Fries at Joe's, the economic way of thinking indicates that the consumer should compare the benefits expected from two plates of Cheese Fries with the cost of both. Having airlines notify the FAA of flight cancellations so that air traffic controllers can make more efficient use of scarce airspace illustrates the economic principle that Air is a free good Secondary effects are usually unimportant.