Most classical liberals respect property rights as the foundation of a liberal economy. One definition of a property right is a state granted monopoly on the use of an object.
Many consider John Locke the founder of classical liberalism. In a Lockean state of nature (see chapter two), people gain property rights by taking the unimproved land and putting themselves into it through labor. Once they have done this, they have a right to the land. They can voluntarily decide who enters it.
Copyright law is very similar to this Lockean viewpoint. I took unused words and put my labor into it to create a story. I now have mastery over this story and may decide who uses it.
Copyright law, however, has many difficulties.
- What if two people write the same book independently? What if someone
else's book is just very similar?
- How does copying your book harm
you? What about my right to do whatever I want on my property?
But land ownership also has many unclear difficulties as well.
Can I play my music very loudly if it enters your land? Exactly how
loud? What about my right to do whatever I want on my property?
What if I take the oil beneath your land while only drilling on my land?
- Can I go on your land at night or if you're not there? What if I'm
very quiet and respectfully leave as soon as I see you? How does that
harm you?
Based on their similar origins and a broadly similar level of difficulty in defining and enforcing, it is reasonable that a classical liberal could find copyright law an acceptable form of property rights.