Great article on the economics of intellectual property, using algebraic economics.
The purpose of copyright is to increase social gain. It does this by:
1. Providing protection from piracy so that producers have improved odds of getting producer surplus.
2. Expire so that the works that are produced maximize their social gain by becoming free after a certain amount of time.
Unfortunately copyright law is doing the second purpose pretty poorly. The 95 year time limit in the United States is far too long to maximize social gain. After 95 years very very few works still have social gain left to be gained by the freedom. Also there is no requirement that the full source code be provided at the expiration of the copyright. This means that for a piece of software it will take 95 years to get freedoms 0 and 2, and freedoms 1 and 3 will never happen unless the publisher wishes them to.
