Two of James Boyle’s great distinctions in Public Domain are between rival and non-rival goods, and excludable and non-excludable goods.
A rival good is one that, if shared, is diminished. A non-rival good is infinitely reproducible–like fire, or the hum of a song, or any meme.
An excludable good is one I can keep a body away from forever. A non-excludable good is one that, once known, cannot be taken back–a story, a crying memory, a quiet evening.
Rival and excludable goods are what the language of property is best suited to describing. I can own yarn, I can have a tattoo. I cannot share my yarn without having the less of it, and excluding a body from taking my tattoo is the only way of saving my own skin.
The language of property is less efficient with non-rival and non-excludable goods. Can I own music? I can own the set-down husk of music–a recording, or lyrics-sheet, or notes on paper. But once sung, I cannot claim property in how it winds in the minds of my listeners. I can demand, for a limited time, that they not sing the song or say it is theirs, because that may help me to sing another song for them to learn, but I cannot prevent the tune’s egress into their minds. I cannot exclude my listeners from their memories of my performance.
Likewise, I do not lose my idea of how to form a free society when I whisper it in your ear. If it is your mind is fertile and the idea ripe, it will plan and grow and grow and be constantly transplanted and -ported. I can have an idea but that ownership cannot imply sole possession unless it is a secret untold to anyone.
This distinction, between yarn and music and tattoos and ideas, is subtle and we are not well-trained to hear it. Anti-plagiarism policies in our elementary schools teach us that ideas can be stolen, like paper-clips or ice from the teacher’s lounge. Labels on our movies and CDs constantly buzz to us that our use of ideas-set-in-form are regulated, seemingly forever, by powers bearing federal seals and bold, harsh fonts. We have in-fact been trained away from seeing this distinction, fitted well with copyright-blinders.
But difficult as it is, we must make this distinction because it is one one which our democracy is built. Thomas Jefferson knew ideas must spread; don’t you think it’s time we knew it too?