I've often had the experience after presenting a paper arguing that copyright doesn't work, that someone asks "So you don't mind if I take your name off this paper, and put my name on it and redistribute it, right?" Although intended as a joke, it isn't really funny, because it demonstrates a lack of understanding of what the paper is about. Suppose I download a piece of music that I didn't previously have. Ignoring the future consequences regarding music production - it is certain that from a social point of view what I did made society better off. It made me better off - I have access to music I didn't have before - and nobody is worse off. They copyright holder might not be able to sell me music in the future - but that is just a transfer payment from me to him - it has no social consequence.

Contrast this to identity theft. I make a copy of your identity - that is, I masquerade as you. This equally certainly makes society worse off. The essence of identity is that it must be unique. If multiple people hold the same identity, then the identity loses its social value. This is why trademark is different than copyright. Copyright prevents the socially desirable use of creations; trademark prevents the socially undesirable theft of identities - it preserves the right to know who you are doing business with.

How does plagiarism fit into this? Plagiarism is the theft of identity. When you take my name off the paper and claim you wrote it, this is identity theft - you are claiming to be me. It serves no socially useful purpose, and indeed has bad social consequences. So while I am against copyright, I am for trademark, against identity theft, and against plagiarism.

This all depends on how you define identity. There are numbers of methods of identity assumption and classes of identity, especially as it pertains to ownership and economics. For example, my wife and I own our house (and just about everything) jointly. Our identiy is, to a very great degree, incorporated and shared. My 6-year-old son owns very little without one of us to "help him own it." I "kinda" own some other things at the suffrance of the bank that has loaned me the money. If I am part of a larger organization, a company for example, my identity is even more "corporate" when it comes to how "I" am defined in terms of what I may do, where I may go, my rights, etc. These "rings of identity" radiate further and further out in terms of describing who I am as members of various groups and classes; employee, citizen, etc. So... as far as that company from whom you downloaded the music is concerned, you have, in fact, committed identity theft. You are masquerading as a member of the class that has the legal right to listen to their music. You have stolen the identity of someone who has paid for the tune. I don't see the difference between ripping off music and ripping off your paper. You enjoy the benefits of the song. I enjoy the benefits of the paper. If the author is not consulted or compensated... what does it matter if the loss is economic or social?

This all depends on how you define identity. There are numbers of methods of identity assumption and classes of identity, especially as it pertains to ownership and economics. For example, my wife and I own our house (and just about everything) jointly. Our identiy is, to a very great degree, incorporated and shared. My 6-year-old son owns very little without one of us to "help him own it." I "kinda" own some other things at the suffrance of the bank that has loaned me the money. If I am part of a larger organization, a company for example, my identity is even more "corporate" when it comes to how "I" am defined in terms of what I may do, where I may go, my rights, etc. These "rings of identity" radiate further and further out in terms of describing who I am as members of various groups and classes; employee, citizen, etc. So... as far as that company from whom you downloaded the music is concerned, you have, in fact, committed identity theft. You are masquerading as a member of the class that has the legal right to listen to their music. You have stolen the identity of someone who has paid for the tune. I don't see the difference between ripping off music and ripping off your paper. You enjoy the benefits of the song. I enjoy the benefits of the paper. If the author is not consulted or compensated... what does it matter if the loss is economic or social?

I don't think this is a case of stealing of an identity. Using someone else's identity to open a bank account or to set up a webmail account are examples of identity theft. But to pass oneself off as the author of your paper is more like stealing an attribution. In the former, what was used was your name, while in the latter, the attribution to your work/effort taken.

The essence of identity is that copying identities is pretty unambiguously bad. That there are lots of rings of identity doesn't really enter the picture. By way of contrast copying a song and selling it does not harm other copies of the song - it is a good thing, because it means society as a whole has more songs to enjoy. The issue with plagiarism isn't ripping me off - it is depriving whoever you provide the paper to of the identity of the person that wrote it. So with trademark, claiming to be Rolex cheats your customer of knowing who he is doing business with. If I copy a Beatles song and give it to you without removing the authors' names you understand that you are doing business with me, and that the song was created by the Beatles. I am only masquerading as a member of the class that has the legal right to listen to someones music if I claim to be such a person - I can illegally listen to the music and honestly report that fact. And without copyright, I would have the legal right, so there would be nothing to lie about. If I copy a Beatles song and give it to you claiming that I wrote it, that is a lie, and a lie that serves no useful economic purpose.

Don't confound the issue of compensation: there is no obvious right or economic rationale for being compensated a particular amount or in a particular way.