THE HUNGRY MAN(@FTChinese)

Dear Economist,

I have a question for you. You have a piece of bread and you are full enough to give it to someone else. In front of you, 10 guys are waiting for your charity. You can say only one sentence to them.

But with only this one sentence, you need to find out who is the most hungry guy. What are you going to say?

Dear Myeong Hyeon,

This is an interesting poser, although in fact I would run a mile if confronted by 10 hungry guys clamouring for my focaccia. That is, perhaps, quibbling, but my main complaint about your question is more serious.

Perhaps you believe that there is little difference between economics and the parlour games of logicians, but in this particular case there is all the difference in the world.

A basic proposition of economics is that talk is cheap. Nothing these worthy fellows could say conveys any information to me. A crook can tell the same sob story as the most desperate beggar.

One possibility, then, is that I could carry out intrusive background checks on these characters. However, that is expensive and tiresome for all concerned - and since the largest providers of pieces of bread are governments, there are concerns over abuses of information, too.

Alternatively, and more elegantly, I could hand over bread only to those people who give me a signal that a well-fed con man would not be willing to give. For example, I could demand that the recipient of the bread first wallow in a muddy puddle. But this, like many signals, is wasteful. Better if the signal was also socially productive, so that I could hand out bread in exchange for useful work. We call this arrangement “getting a job”.