A certain credit-card company awards its customers bonus points for using its credit card. Customers can use accumulated points in the purchase of brand name merchandise by mail at prices lower than the manufacturers' suggested retail prices. At any given time, ttherefore, customers who purchase merchandise using the bonus points spend less than they would spend if they purchased the same merchandise in retail stores.
The assumption that the merchandise available to the company's credit-card customers using the bonus points is frequently sold in retail stores at prices that are higher than the manufacturers' suggested retail prices is on which the argument depends.