Intellectual Property, the argument

Intellectual Property is perhaps the most disputed corner of libertarian thought.  Some libertarians are pro-, others are against, and there are many sides to the argument.  After a conversation with a friend, in which he pointed to occupational licensing as one of the major injustices of the day, I countered that I'd recently been thinking that IP law should go in that category.  He suggested that he'd love to see a discussion of I, and I haven't found any recent ones beyond this bit from Dr. Long.
 
As always, I'm prone to acknowledge that it's not a one-sided discussion, but here's the libertarian argument.


Disclaimer: my primary expertise is in teaching first, education-in-general second, and writing software third.  I am mostly a performance artists, but one who would have a hard time being duplicated.  Hence I shouldn't have too much of an interest in IP law for my own benefit, even though I am writing education software.


Against:

• The justification of property rights is founded on scarcity.  If I'm growing crops on a plot of land, you can't grow crops on the same land.  Intellectual Property (a song) is not scarce, therefore you can't use the same justification for it.
• The value in ideas comes from combining and recombining.  "Good artists borrow, great artists steal" (variously ascribed to all great artists).  The business of copyright & patent has a tremendous chilling effect on good art, as the great bits of one (recent) thing cannot properly be reused in the same ways that all historical art has.  Ditto other countries' approaches to IP.  Ideas are shared. 
• In reality, while real property rights are bottom-up (agreed, naturally, by people in the absence of government), IP is top-down.  IP is a creation of the government.  Specifically, a patent (or copyright) is the same kind of animal as a monopoly: the right to extract unreasonable profits from the  populace by means of government restrictions on others doing the same job.  Formalized for a few years in ancient Greece, and then again in 1623 in England.  Apart from that, patents were unknown.  In China, IP law was instituted for the first time in 1985
• If you look at the impact of IP law, it works almost identically to other government granted monopolies.  The primary beneficiaries of the law are (a) large corporations that play the legal game and (b) lawyers.  The benefits to individual artists are quite mixed.  They have some control over their own works, except insofar as the RIAA owns the copyright...however they are prevented from using others' work (see Disney).  Patent law is almost identical, with patent-thickets being a modern large-corporate strategy by which they prevent themselves from being sued by other large companies and can prevent smaller players from playing at all.
• According to New Growth Theory, economic growth is (basically) the growth of ideas.  Patent law very simply prevents ideas from being combined.  Therefore there is a real (and substantial) cost to economic growth from having patents protect new inventions. 
• Coase, my other favorite economist, points out that transaction costs are the root of all evil.  Patents create transaction costs on idea-usage.  Even worse, this effectively prices the poor out of the market.  This is between bad and horrible. 
• It is unclear whether under current hyper-competitive pressures, patent law would make any difference at all in companies creating new ideas...If new ideas aren't adopted in a company, the company in the market that does adopt new ideas has a competitive advantage.    
• Software, Business Method, and Gene patents are both absurd and morally wrong.  Math is unpatentable, so is science.  Software is math, in the form of algorithms.  Genes pre-exist.

IP Law: Unjustified, Anti-value, Government-created, lawyer-favoring, Growth-slowing, poor-excluding, unclear benefit, and some categories are horrid.

FOR:

• IP law encourages the creation of ideas, which encourages growth.  If I, Joe Plumber, have a better way to make a toilet-snake, I might only do so if I have a reasonable expectation of making a profit off my idea.  Similarly, without IP law, a Chinese firm might wait for an American firm to create an idea, but then produce it more cheaply, thus decreasing the incentive to create new ideas.
• It is a moral good for artists and inventors to receive payment for the fruits of their labors (which are mostly mental), regardless of how you justify it.
• In the case of Pharmaceuticals, given the current regulatory structure (FDA!!!), it is so costly to create new medicines ($500M-$1B????) that without the promise of IP-law based monopoly, there would be no new (or at least massively reduced) development of drugs and medical devices.  

IP Law:  Morally just, Encourages idea-creation and therefore economic growth.  Medical advancement requires something like IP law.

OK.  It's blatantly obvious which side of the debate I'm sitting on.  Are there arguments I'm missing?

Summary:

• It's unclear whether or not IP law encourages growth.  While first analysis says it does, second analysis is, in my opinion, opposed.
• It's not justified under normal property-like considerations, on close examination, though it looked like it might be on first glance.  
• In theory, it should benefit artists and inventors.  In reality, it mostly benefits Disney, IBM, the RIAA, and lawyers, and sucks for poor artists + inventors.
• May be a necessary evil (given other crazy laws) in the case of drug/medical device development
• Some categories are especially atrocious.