I'm answering in reverse order because I think a lot of this comment covers stuff that we don't really disagree with. Thus I will answer the conclusion and then I put my responses to everything else because I find them interesting, but not required for what I want to convey.
> Copyright duration is too long. But the fundamental difference between rivalrous possession of physical artifacts and infinitely reproducible ideas really needs to stay the hell out of these debates. It's a tired, empty talking point that doesn't actually address the substance of what IP laws are really about.
I would argue that it is perhaps the opposite of tired: ironically less relevant in the past and more relevant as technology advances and mere thought experiments become practical reality. I think many of these issues weren't dealt with in the past because these edge cases existed as mere hypotheticals. Kind of like a mathematician saying that copyright doesn't make any sense because he could write a program that iterates through all books. Lawyers just roll their eyes not because they have a counter-argument, but because they don't think that scenario exists as something they'd ever have to deal with. I think the idea of a computer that reads all the text in the world and learns from it is definitely tied to the questions of unresolved issues with the nature of data, but would have until very recently been considered an annoying hypothetical in a serious discussion about copyright, allowing us to actual dismiss it and continue not addressing it.
We all agree that copyright is too long. And I also think this would just become a non-issue if we had a reasonable duration for copyrights. Even if you philosophically disagreed with it, it wouldn't be worth arguing over vs. just waiting it out.
> This is a stupid argument, no matter how often it comes up.
I knew bringing this up would rekindle these arguments from 20 years ago, but it was necessary for a later point, so I was hoping I was making it value-neutral enough that it wouldn't trigger this, but I guess I was wrong.
To be clear, I am not making the same argument you have seen several times before. I am making a strictly weaker argument. The only goal of this distinction is to demonstrate that these properties are "different", and that the law aims to make "intellectual property" behave like physical property. Notice for example that I didn't then assert that IP thus doesn't exist. I didn't even argue whether this goal of matching the behavior was good or bad. I am simply stating that it doesn't by default behave the way we seem to want it to, and, people don't seem to intuitively ascribe the same morality to it either. My only intention is to make the point that this goal thus requires work, and (as I'll explain in more detail below), more work than in the physical case. So far I don't think there is anything necessarily unreasonable about this as a set of premise conditions for establishing the terms under which the public at large agrees to take on the costs of maintaining said system.
> A bunch of stuff about Alice making sandwiches and drawing pictures
Disclaimer: I don't think we're really in disagreement about the important points, and I don't think this section is relevant to the important points which I return to below, however I find it intellectually interesting to talk about, so I have a retort here, which I believe is just an unrelated digression
These analysis of Alice making sandwiches and drawings (IMO) misses the actual meaningful differences in these scenarios since it (IMO) focuses on the uncontroversial, but also irrelevant, breach-of-contract issues. In both these scenarios, the issue is not really the "property," it is the refusal to comply with a previously agreed arrangement. You can see this if we add a third scenario where I pay Alice to do jumping jacks for a week, she does them, and then I refuse to pay at the end of the week. No need to pay you, you already did the jumping jacks. No one "got" anything here, other than I guess "satisfaction" or "exercise". We can make the example even more abstract by having me pay Alice to do nothing all week, and she once again does a great job by sitting quietly in her room all week, and then I once again don't pay her. The sandwiches and drawings are just props in the original examples -- they're not actually necessary since this is a contract question, not a theft question.
The actual interesting aspects around the sandwiches and drawings are 1) what happens much after this transaction, and 2) what happens with third parties. With the sandwiches, "what happens after" is straight-forward. I either the sandwiches, resell them immediately, or they go bad. There's not much interesting there. No one needs to think hard about the "ramifications" of the sale of the sandwiches. Compare this to the drawing. What if after I have paid you, just like we agreed, I proceed to make my infinite copies. You might think that's not fair, you thought you'd have a repeat customer. I assumed I was free to do as I please with the drawing. In fact, ironically enough, in this instance if I treat the drawing like physical property, where the expectation is I can do as I please with it, it ironically creates this conundrum because "putting the paper in the photocopier" is in the set of "do as I please". But let's go one step further, what if I make all those copies and then sell them.
I'm sure you'll now respond that the royalties or usage rights were all implied in your original story. Great! But that's my point. Those were required. You needed a supremely complex web of laws and binding contracts (and litigation if they aren't followed) as a necessary component of that transaction due to the existence of degrees of freedom that simply don't exist for the sandwiches. You can write up a contract around the resale of a sandwich, but most sandwich shops don't because me eating sandwiches for the rest of my life by copying the original sandwich isn't a realistic scenario (so no need to price that into the original cost of the sandwich), and me out-sandwiching you by carbon-cloning the sandwich isn't feasible, and even if it was it would still have material ingredient costs that would bound its effect on my shop, and even "figuring out the recipe" isn't that much of a worry since you still need to like buy ingredients and make sandwiches as opposed to hitting paste over and over. These scenarios are dramatically different, and that's why sandwich shops usually don't employ lawyers but design shops do. And again, we didn't even go into third parties. What if someone manages to somehow make a copy of your image just as you're handing it to the client. Now both of you are in compliance with your deal, neither of you is angry at each other, but there's this weird situation where you were never expecting to get money from me, but I have a copy of the picture now, and it's really hard to reason about what that means in terms of "gain" and "loss" if I never do anything other than hang it up in my room. This is simply not possible with the sandwich, no one could quickly "copy the sandwich" in transit and potentially introduce an entirely new threat to your business.
Again, my only point here is that it seems very strange to insist that there physical property is identical to intellectual property, and that it isn't fairly complicated to make intellectual property approximate the relationships we have with physical property. And to be clear, nothing even derogatory has been said about this goal yet. You could take everything I've written in this comment so far, and use it as part of argument for copyright. However important is it precisely because of the explosion of complexity in possibilities that simply don't exist for the vast majority of physical items.