Murray Rothbard on Patents

It is by no means self-evident that patents encourage an increased absolute quantity of research expenditures. But certainly patents distort the type of research expenditure being conducted. . . . Research expenditures are therefore overstimulated in the early stages before anyone has a patent, and they are unduly restricted in the period after the patent is received. In addition, some inventions are considered patentable, while others are not. The patent system then has the further effect of artificially stimulating research expenditures in the patentable areas, while artificially restricting research in the nonpatentable areas.

Murray Rothbard, Man, Economy, and State.