A seller is not obligated to inform a buyer of anything about the merchandise that the seller offers for sale except for the demanded price. It is the responsibility of the seller, not the buyer, to make sure that the amount of money a buyer gives a seller in exchange for merchandise matches the amount that the seller demands for that merchandise. The obligations that follow from any social relationship between two people who are well acquainted override any obligations that follow from an economic relationship between the two. A buyer's sole obligation to a seller is to pay in full the price that the seller demands for a piece of merchandise that the buyer acquires from the seller.
Sharon, a noted collector of fine glass, found a rare glass vase in a secondhand store in a small town she was visiting. The vase was priced at $10, but Sharon knew that it was worth at least $1, 000. Saying nothing to the storekeeper about the value of the vase, Sharon bought the vase for $10. Weeks later the storekeeper read a newspaper article about Sharon' s collection, which mentioned the vase and how she had acquired it. When the irate storekeeper later accused Sharon of taking advantage of him, Sharon replied that she had done nothing wrong.
Which one of the following principles, if established, most helps to justify Sharon's position?