A couple of colleagues of mine collected a list of answers from a recent midterm in a first year college Economics course. The question was simple enough: Define a "public good". Most of the students knew that a public good is essentially a good that is a good that is difficult to exclude someone from using, and that one person's use does not deny someone else the use of that good. A public park or clean air are typical examples of public goods.
Some of the students who didn't know, however, tried to get points for the question by being a little bit creative. Here are my 10 favorite answers to the public good question, along with my commentary:
10: A good sold by a private sector into the public.
This student probably gets just as confused as I do when British people talk about paying tuition to go to a public school.
9: A good that everyone can have, but do not have to pay taxes for.
A good in which everyone can have, but don't have to pay taxes for? I'll take two.
8: Good available to all people, in some case is something sold from a store available to all people.
I guess public goods didn't exist in the South until Jim Crow laws were abolished. Not many goods can be considered public goods if you're on a grad student salary.
7: Good that belongs to everyone / society as a whole.
Normally we call that communism. I don't know why I get this image in my head of an angry talk-radio caller shouting that the Commies are ruining society with their public goods, but I do.
6: Something that no one has right to use/sell without everyone's agreement.
We'd never get anything done if we had to make sure that everyone agreed to an economic transaction.. even people who are unaffected by it. Well, maybe if you lived in a very, very small town you could sell something without a busybody saying they don't agree.
5: Something that people will always need.
A mother's love is a public good?!?
4: Good issued by the government.
I don't think this is quite it either I mean, the government gets pretty cranky when you let other people use the Social Security Number that they issued to you.
3: A public good is not in the market too often because free riders will take advantage of it. E.g. CD free riders download music in their computer or rip the CD. Copyrights do not help much because people will still download music.
These are the kind of answers you get when Metallica drummer Lars Ulrich in your class.
2: Which anyone can buy or sell.
Anyone interested in owning a piece of the Brooklyn Bridge? For you, it's only 5, because you're so nice!
1: A public good is.
This is probably the all-time greatest definition in the history of economics. It has an existential quality that I'm quite fond of, plus it seems pretty difficult to argue that it's wrong.
There were a dozen or so other candidates, but these were my favorites. Now remember kids when the smart-alecky teaching assistant gives you a 0 for an answer you thought was quite creative that you're not alone. Part-marks are only given for answers that don't make us laugh and for students who bring us coffee.