UPDATE: The more I think on this subject, the more I find that coercion of any kind is wrong, which may in the end bring me to an anarchist. I hope not, but we'll see.
The question rapidly becomes one of the purpose of a human in society--as opposed to a human on his own. To take an Aristotlean view, a human must have society in order to be virtuous: such a quality cannot exist in solitude. Excellence, perhaps, but not virtue. So we create laws to allow such a construct (society) to function. But to what end this functioning; that is, why do we have law?
Society brings other benefits as well. Specialization leads to increased efficiency, as Mr. Smith has pointed out. And increased efficiency means that we can enjoy the material things more frequently. I am currently snacking on chocolate-covered espresso beans, until now without considering the distance the beans must come, the history of chocolate, the skill of the confectioner, etc. Such a luxury would be impossible were one to be alone in the world. But I'd like to argue that the material goods of cooperation are a secondary, accidental benefit. I'll do so after work sometime. Right now I need to make more money, to buy more candy.
