单选题 I" m in the unusual position of being both a computer scientist and a professional musician. On the computer side, I" m best known for my work in virtual reality, a term I coined in the early 1980s. As a musician I write, perform, and record my own work. Canons for Wroclaw, a concerto I created for virtual instruments, was performed last December by the Chamber Orchestra of Wroclaw, Poland. All of this means that I have a few deeply felt ideas about Napster, the free software millions of people use to share their music collections over the Internet. Big media companies see Napster as theft because they can" t collect royalties when people use it. So they have asked the courts to kill it. As I write this, a settlement seems to be emerging. Napster will probably begin to charge for its services and pay royalties to at least some record companies. Whatever happens, the legal decisions surrounding Napster are important for reasons that transcend the music business and extend to our basic concepts of what it means to be free in a democracy. I believe the anti-Napster forces have failed to foresee dangerous implications of their course of action. They aren" t thinking about the harsh logic at the core of this technology. They do not understand what I call the Law of the Excluded Digital Middle; Digital tools can be either open or closed but resist being anything in between. An open digital tool is one that can be used in unforeseen ways. A tool like e-mail, meant to send text, might also—surprisingly—be used to send music. A closed tool is one in which there are technical restrictions that prevent unforeseen uses. The advantage of open tools is that more people can create new things with them; consequently, they tend to be more innovative. Closed tools are usually created because it is thought they will be more profitable; An owner can control them well enough to enforce bill collection. Of course, the open software movement energetically promotes the idea that innovation ends up generating more money than control does.