> So are we talking about "ownership" like name a star catalogs? or the "adopt a zebra" at the local zoo?

Yes, I think is an apt reference, though an important component that critics who use it to disparage that is missing here is that the issuer of the ownership certificate is the creator of the artwork, and can therefore claim a moral right to do so; this is not the case with a company selling stars. A zoo maybe is closer to being able to claim to be some kind of authority. It's interesting to think about: Would we give a star registry run by NASA more credit for being non-scammy?

Do you feel the same confusion about what ownership means when museums buy immaterial or digital artworks for which they only receive a paper certificate (or indeed, not even that, as in the case of Sehgal)?

> What does that ownership mean and what can a person do with it (besides selling it to another person)?

Yes, nothing. You can feel like and claim to be the owner, and there is a community of people who respect that. For example, and this is the case today, by common agreement if a museum or gallery were to want to display a digital artwork that was issued as an NFT, they would certainly not do so w/o permission from the artist, and the artist would be expected to defer to the collector who owns the NFT.

Real-world laws about intellectual property certainly intersect here, and creators do often provide license agreements along side the NFT which are supposed to give legal clarity about their legal rights; sometimes CC is used, and on occasion some are given into the public domain.

> And if the hosted file somewhere that it purports to claim ownership of moves to another site/url/resolution (or even goes offline completely) what does that "two or more parties can agree on what piece of art the token represents" mean? Is it "that URL is offline so lets pretend that the image is over there is what this represents?" What if that other image has a different NFT that claims ownership?

What's the relationship between the file and the artwork? If the artist exports their Adobe After Effects composition into a 1080p clip, but still has the source file around on their hard drive, and later exports a 4K clip, is this now a new NFT that someone else should own? The artist can of course release as many NFTs and editions as they want, but conceptually, it's the artwork that the token represents.

What you want is not to forget or disagree on what the token represents. For the most famous NFTs, that is maybe already unlikely, but a good solution is to store a hash of the file (or /a/ file representing the artwork) with the token.

> What if that other image has a different NFT that claims ownership?

I can create a 100 NFTs right now that points to any Cryptopunk, or to the $60 million beeple piece, much in the same way as I can issue paper certificates representing a Sehgal or Sol Le Witt artwork; these would presumably not be desirable.

I find people become confused with the URL, but as I said: early NFTs experiments did not have them. Just imagine all NFTs w/o them, and just a hash of the file. To see what the NFT looks like, you have to go to the website of the artist, where the image is available. The collector may keep their own copy. If you want to display all your NFTs in an app, the makers of the app have to go around collecting the images of each NFT manually. Maybe the artist's galleries would take on the job of submitting the images to a place like artsy.com, so a registry could be built for easy lookup. That would all be conceivable, and again, very similar to how some art is sold using paper certificates today.

Then someone came up with the idea of adding a URL alongside the token to just make this all easier.

Rafaël Rozendaal was famously selling websites as artworks via ownership of the domain, w/ the collector then simply being responsible of keeping them online.

> Personally, I'm waiting for it to be decided somewhere in court where either everyone who has fraudulently sold NFTs for works they don't hold the copyright on go "oh crap" or everyone else realizes that its digital performance art and has no other value.

(Aside: Stolen artworks are not really a big part of the NFT market; there is a bot epidemic, yes, but those works remain mostly unsold.)

> For example, if I sold a NFT for an image hosted on a server and then sold the art (and its copyright) to someone else who then removed its presence from the net and hung up a print in their own private gallery - is there anything that the NFT owner can do about it?

> If the answer is "no", then it's as meaningful as names in a star catalog. If the answer given is "yes", then somewhere, someone believes that the NFT has meaning in the legal framework of the practical world.

I hold our legal system in great stock, and I know it as one that is very adaptable. There are probably a number of possibly legal claims that could result from an NFT transaction. Having said that:

The intellectual property is not on sale - as it isn't with physical artworks or paper certificates.

There are probably some practical license rights the collector requires for their own enjoyment of being the owner of the artwork. If nothing else, the right to have access to a copy of the file.

Ultimately, if the artist themselves (or a possible subsequent copyright holder) were to renounce the NFT and insist that no one may own a copy of the file, including websites were such NFTs are being displayed, then maybe the collector is just out of luck. But that's ok. After all, they are already relying on the artist to manage their career well, if they are hopeful that the NFT will have some kind of value in the future, which most of course won't.