You make it sound like we should assume that getting inspiration from a few hundred or thousand art works that are very famous and highly public is the same as training over nearly every available public piece of art. I see no reason why that should be our null hypothesis.
Humans either learn art by being natural art geniuses, or by receiving instruction and learning through an iterative process (where, again, they might create thousands of art works, but nowhere near the scale here), which is very different.
#2 is pretty interesting. After all, the purpose of copyright law is to encourage creative works. If we have machines that can generate creative works on demand with little effort, what purpose does copyright law serve?
I am not a lawyer, so the following is only my opinion.
Copyright law serves the purpose of peoples works being protected from unauthorized parties making copies of their works, and profiting off them.
It doesn't protect from technology making the production of new works cheaper, faster, more efficient. An artist using photoshop can be, and is allowed to be, many times faster than one using oil and canvas.
I don't mean to suggest those are the only options, or that either one is even practical. The point is to determine where the objection lies: with the method or the outcome.
Hm, okay. In that case, I would say the first is a problem, and the second is also, but differently.
I think the objectionable thing about the second is that the AI knows everyone's styles, and so can use them in creating something new. Even if the AI is restricted to not be able to paint an image in a certain artist style (as the new version of stable diffusion is, for instance) and the art is unique, I think part of the problem is that the AI is still (presumably) leaning on the collective styles of everyone it has trained over.
If we can train an AI over a small dataset or maybe even a large dataset of old art, or some mix in between, and then maybe fine tune it wtih a snall sampling of modern art, then I believe it would be unobjectionable, as this is largely how humans do it.
The only difference that matters, is scale. And again, if I want to argue that something done 10000000000 times is legally problematic, I have to be prepared to explain why doing it 10 times is problematic as well, only less so.
The question isn't if a scaled up thing is the same, the question is if a legal thing scaled up suddenly becomes illegal for no other reason than being scaled up.
Nothing new. People differentiate between genocide and murder, for example, or poisoning water supply vs an individual poisoning. Criminal law in quite a few places definitely has scale considerations.
You just gave two examples of where both ends of the scale are illegal, which only strengthens the argument of GP. IANAL, and I'm not stating anything about the reality of the judicial system, but only following the logic of the argument.
My examples only were meant illustrate that scale is a well known "thing" in legal systems and I happened to pick things with two illegal endpoints (IANAL).
You could look at other things like the need for permits for certain things as a function of size and use, if you want simple examples for scale mattering and legal endpoint(s).
I am no lawyer, so the following is only my opinion.
I am completely aware that scale is a "thing" in legal systems. But as I said before: For scale to be important, the unscaled act in itself has to be problematic already.
Humans either learn art by being natural art geniuses, or by receiving instruction and learning through an iterative process (where, again, they might create thousands of art works, but nowhere near the scale here), which is very different.