This sounds so insane to me. If I own land and grow a tree on it, the tree and its fruits are private property forever (mine until I die, then inherited by my children, then their children, or sold, transferred, etc ad nauseam). At no point does the tree become "public", that would be utter nonsense. It is property. Why should my ideas then be anything different? They come from my head. I own myself, including my head, thus I should own the fruits of my head like I own the fruits of my tree and they should remain property forever. The fact that copyright expires is one of the great tragedies of modern life, though at least I can take solace in knowing I own my ideas until I die.
Copyright law exists exactly because it is universally accepted that ideas are not property: Copying an idea or expression of it does not deprive you of your ideas.
The entire notion of "intellectual property" is the creation of an artificial monopoly rooted in very distinct and separate goals from physical property that requires separate laws if you want to restrict copying or exploitation, because property law explicitly does not cover them.
Most copyright laws are also justified implicitly or directly in the legal texts allowing them as creating an incentive for the advancement of the arts and sciences - a temporary monopoly right granted by the state as a deviation from perceived "natural right" - on the belief that granting that right creates more benefits for the public than not having them, by encouraging the creation of more works.
And no copyright law protects your ideas. They protect the specific expression of them. Patents - which do protect ideas - are by design far more restricted and limited exactly because they are far more invasive in depriving the public of use of the very idea for the duration.
Did you spend your entire life in isolation from the rest of human society? Because if not, then you have been influenced throughout your life in a multitude of subtle and not-so-subtle ways by the works of others. In what way, then, are the fruits of your head entirely yours? We're all standing on the shoulders of giants.
Unlike the tree, nobody can take your idea away from you. You retain possession of your idea even if somebody copies it. It sounds insane to me to think you should get permanent control over other people's communication just because you had the idea before them.
Perhaps, but that is your tree, if someone takes a cutting from your tree and grows it into their own tree you shouldn't own that tree, your tree is still there.
Eventually you get to the point where someone asks why the tree is theirs and they say it's because someone in history planted it, they were a relative, so it is mine now. It is hard to assert a moral justification for long term hereditary ownership without inviting investigations on how it was those ancestors came to have the resources that caused the ownership to begin.
It's not a "should" -- ideas simply are fundamentally different from physical materials, and the norms we use to deal with the inherent qualities of one don't automatically translate over to the other without a suitable rationale.
Physical materials qualify as property because they are economically rival: one party possessing and using them inherently excludes others, meaning that competing claims to the same thing must be resolved by one party surrendering their claims to the other. There's no agree-to-disagree mechanism available, so we need a way to resolve disputes in favor of one party or another.
There is no clear application of this to non-rival intangibles: there is no conflict between two people using similar ideas independently of each other in the first place. Someone copying your idea isn't analogous to them picking fruit off of your tree, it's analogous to them learning from what you're doing, and then going off and planting their own tree on their own land.
Modern "intellectual property" is a contrivance by people desiring to artificially incentivize certain categories of activity by attempting to replicate one of the downstream effects of the inherent exclusivity of goods, namely commercial markets. So you wind up with a positive-law intervention to create artificial scarcity in order to produce similar second-order consequences to what comes about when scarcity exists naturally.
That's why property rights have been recognized in all civilizations in human history -- and are likely a prerequisite for organized civilization to exist in the first place -- whereas copyright laws in their modern form date to the 18th century.
In fact, artificial "intellectual property" conflicts with natural property rights, in that in claiming a universal monopoly on arranging any bits of matter into particular patterns, you are actually claiming the right to stop people from using their own actual property as they please.
Such a weird take. What are the similarities between your fantasies and land that to you make the philosophical convictions involved in private property laws applicable to those fantasies? Why isn't it good enough for you to fantasise about land and a tree, and why doesn't the answer to this undermine your reasoning?
Personally I'm not convinced by the arguments for private property, which makes your comparison even weirder than you likely intended.
