Volokh and Solum on IP Rights

Here’s an interesting blog-dialogue (blogalogue?) between law professors Euguene Volokh and Lawrence Solum concerning the nature of the intellectual property rights and trying to find an appropriate analogy in the world of tangible property.
Volokh: The Conceptual Plausability of Intellectual Property
Solum: Volokh’s defense of Intellectual Property
Volokh: Larry Solum on IP
Finally, the most thoughtful and well-researched (in other words, long) piece, Solum: Water Wells and MP3 Files: The Economics of Intellectual Property