I'll comment on one argument here:

Copies of an author's work can be made virtually for free; therefore they aren't "scarce"; therefore they have no value that anybody need respect. This line is not heavily stressed by B&L, but it is popular among anti-IP'ers and was apparently originally conceived by their darling, Stephan Kinsella. Nonsense! The actual worth of a work can be calculated as the sum of what each person on earth would willingly pay for a copy, if it could be obtained in no other way. This figure may fairly be said to represent the potential value the author has brought to the world. Subtract the cost of making copies for all purchasers, and we arrive at a return the author may hope to approach in a just society, assuming he's able to reach all potential buyers and is able to guess how much they're willing to pay. Note that this second number goes UP, not down, as the cost of making copies decreases. An interesting question for anyone who buys into the Kinsella argument would be: consider a product which requires physical raw materials to produce. Would it be "not stealing" to break into a store, take one, and leave in exchange only the cost of the raw materials and labor needed to produce it? The idea is as absurd as Kinsella's is for intellectual works.

First, I have stressed repeatedly that property rights are rights in the physical integrity of a resource, not in its value. Libertarianism does not mandate that people "respect the value" of property. Only that they do not invade its borders--use it without the owner's permission. So it is irrelevant whether a work, or copies of it, "have" a "value". The question is: are patterns and information ownable things? Are they the type of things that can be, that ought to be, property? The answer to this question does not turn on whether people value the pattern or information or copies or not.

As for the question: consider a product which requires physical raw materials to produce. Would it be "not stealing" to break into a store, take one, and leave in exchange only the cost of the raw materials and labor needed to produce it?"

Property rights are rights to the physical integrity of owned scarce resources. So it's stealing to take my product without my permission, since I own it. This is true whether or not the object "has value" or not; and it's true whether or not the thief leaves me partial (or even complete) restitution.

This entire line of reasoning is confused.

(Cross-posted on Mises Blog.)