So I thought I would elaborate a bit on this. The "artificial scarcity" insight is indeed a good one, but it is not mine. From pp. 33-34 of Against Intellectual Property:
Ideas are not naturally scarce. However, by recognizing a right in an ideal object, one creates scarcity where none existed before. As Arnold Plant explains:It is a peculiarity of property rights in patents (and copyrights) that they do not arise out of the scarcity of the objects which become appropriated. They are not a consequence of scarcity. They are the deliberate creation of statute law, and, whereas in general the institution of private property makes for the preservation of scarce goods, tending . . . to lead us "to make the most of them," property rights in patents and copyrights make possible the creation of a scarcity of the products appropriated which could not otherwise be maintained.Bouckaert also argues that natural scarcity is what gives rise to the need for property rules, and that IP laws create an artificial, unjustifiable scarcity. As he notes:Natural scarcity is that which follows from the relationship between man and nature. Scarcity is natural when it is possible to conceive of it before any human, institutional, contractual arrangement. Artificial scarcity, on the other hand, is the outcome of such arrangements. Artificial scarcity can hardly serve as a justification for the legal framework that causes that scarcity. Such an argument would be completely circular. On the contrary, artificial scarcity itself needs a justification.Thus, Bouckaert maintains that "only naturally scarce entities over which physical control is possible are candidates for" protection by real property rights. For ideal objects, the only protection possible is that achievable through personal rights, i.e., contract (more on this below).
 Arnold Plant, "The Economic Theory Concerning Patents for Inventions," p. 36. Also Mises, Human Action, p. 364: "Such recipes are, as a rule, free goods as their ability to produce definite effects is unlimited. They can become economic goods only if they are monopolized and their use is restricted. Any price paid for the services rendered by a recipe is always a monopoly price. It is immaterial whether the restriction of a recipe's use is made possible by institutional conditions such as patents and copyright laws or by the fact that a formula is kept secret and other people fail to guess it." [For more on Mises's view of IP, see Mises on Intellectual Property.]
 Bouckaert, "What is Property?" pp. 799, 803.
Update: Jeff Tucker's article and recent speech had me thinking about something that ties into this post well. People want to impose artificial scarcity on non-scarce things because they think scarcity is good. But they have it backwards. If anything, we should want material things to be non-scarce.
In Tucker's talk, he was pointing out the difference between scarce resources and non-scarce, infinitely reproducible ones. Yes, they are different, but I think we also need to combat another fallacious view: people seem to implicitly think it's bad that ideas are infinitely reproducible. This is a "problem" we need to combat by making them artificially scarce. But it's a good thing. i.e., at least ideas are non-scarce; but unfortunately, material things are scarce. But it would be good if material things were more abundant. So imagine that some benevolent genius invents a matter-copying device that lets you just point it at some distant object, and instantly duplicate it for free for you. So I see a coat you are wearing, click a button, and now I have an identical copy. I see you having a nice steak, and duplicate it. Etc. This would make us all infinitely wealthy. It would be great. Of course people would fear the "unemploymetn" it would cause--hey, I want to be unemployed and rich! And the rich would hate it because they would now not be special. They couldn't lord their Rolls Royces and diamonds over the poor; the poor would have all that (it would be similar to how audiophiles were irked by the advent of the CD so tried to find granite turntables etc. to pretend they were still better). So imagine a rich guy suing a guy who "copied" his car.... imagine farmers suing people who copied their crops to keep from starving... how absurd! And what damages would they ask for? Not monetary damages--the defendant could just print up wealth to pay him off! So the only remedy he could want would be to punish or impoversih the defendant... for satisfation, to once again feel superior. How sick. As my friend Rob Wicks noted, you could imagine a short story based on this in which judge orders a famine as a remedy to crop-copying.