Posner on Copyright

Here is a truly outstanding discussion of the issue of copyright with jurist Richard Posner. Both the questions and the answers are unusually thoughtful. Asked why companies should be allowed to have copyrights if there is no marginal cost to redistribute, say, music, Posner says

Sometimes the companies do have rights that are violated. It is tempting to say that they should get nothing for an additional use because its marginal cost is zero. But that is true of the first use as well, at which point nothing is left to cover the costs of innovation for successful products, and, of course, the costs of the projects that never make it in the marketplace at all.

...If you want to keep the stock of music constant, offer no protection to new songs. but if you wish to see them created, then you have to protect.

Discussion Question.Posner also makes the point the challenge finding an economic justification for Congress extending the term of copyright protection for content that already has been created. The content already was developed, so that extending the copyright confers no incentive for creativity. Can you think of an economic argument for extending the term of copyright protection retroactively?