A big difference that can make it reasonable to have long or even infinite copyright terms is that copyright works are the creations of people's minds, not disc

A big difference that can make it reasonable to have long or even infinite copyright terms is that copyright works are the creations of people's minds, not discoveries about nature. Somebody else creating something doesn't prevent you from creating your own thing that's just as good, or even the same thing if you can show you did it independently. But somebody else patenting a method for compressing video does prevent you from independently creating and selling your own video compression method if it happens to work the same way. Maybe that's the best way to compress video and the world would be denied it as long as the patent remains valid. So nobody really needs to use other people's copyright works. Unlike patented ideas, you can always create your own instead. Or course, sometimes it's expensive and feels like a waste of effort reproducing what's already been done, but it's still not a restriction on doing your own thing the way patents are. The way I see property ownership is that it's like a store of human labor. When you do work, you might get money from it, you might get a physical object from it (I made a table, now I own that table), or you might get a copyright work from it. All of these things can hold the value of the work you did and can be used to trade for other things. I don't think it's unreasonable to imagine that in a fair world, the people who did that work can keep the stored value they created as long as the market is willing to trade things for it. In the case of computer software, some value is lost whenever somebody uses your work, since you're not able to sell it to them anymore. Value is also lost if the the demand falls (obsolete software) but that's the risk of investing your labor in something with an uncertain lifetime, just as the value of a table is lost if fashions change and people want steel tables instead of wood. Some copyright work has value and that's why people want to copy it, so they can gain that value for themselves at the expense of the copyright holder. But wouldn't it be more fair to make your own, instead of siphoning value out of other people's work without compensating them?