While living in Cameroon and Ghana, I learned that you bargain for most purchases. Soon I became good at getting a low price, although not as good as the locals. But when American friends visited, they were appalled because I was (relatively) wealthy and not willing to share my wealth with someone who was obviously quite poor. Was I being unethical? —Edwin Kay

Bargain away! That’s how prices are set, and no sane seller starts with the price she wants to get. Indeed, trade is enlivened, in part, by the fact that each sale is a negotiation. Life would be as dull as a supermarket checkout line otherwise. It’s also a little condescending to think that people will take a price they think is exploitative. The seller gets the money she wanted and hands over the goods she was trying to unload; the buyer acquires the goods she desired for a price she was willing to pay. Against the right background, market exchanges improve things for everybody.

—Adapted from “The Ethicist” in The New York Times Magazine