> I think the point is that the purpose here is not relevant if the function includes the ability to do so. Even if the function also includes the ability to produce things that are, in their totality, substantially different from any given work in the training set.

Before I get into the ability issue, keep in mind that regardless of the future of AI-related law, AI companies already have an incentive to prevent models from producing outputs substantially similar to existing copyrighted works, and the companies already do go out of their way to do the same. And I reiterate that generating something similar to a work in the training set will usually require the user of the model to reference a person (or group), a copyrightable work, or a style strongly associated with a certain person (or group). If the user writes a prompt like that then the user should bears the most responsibility if the result infringes on the copyright to a work in the training set. But more importantly, whether the output infringes doesn't matter until someone publishes it. That someone will be the user who submitted the prompt (and/or the model service provider if the service provider automatically publishes the output by default).

Now I'll address the ability issue.

> I think the point is that the purpose here is not relevant if the function includes the ability to do so. Even if the function also includes the ability to produce things that are, in their totality, substantially different from any given work in the training set.

In the context of regulating AI, I reword `the ability to produce something substantially similar to a work in the training set` (using backticks because you didn't write those exact words) to `the ability to produce an output that infringes on copyright`, and I replace the main subject `model` with `program`.

How do you write a law to regulate

1. a program (the program, not the users of the program) with `the ability to produce an output that infringes on copyright`

without also regulating

2. a program with the ability to download a copyrighted work from a website that doesn't intend for users to download the work in such a way, while keeping in mind that users of this latter program can distribute the work in ways that infringe on copyright?

For example, how do you regulate an image generation model without also regulating youtube-dl? You might point out, in the former case the model produces an infringing work while in the latter case no infringement happens until the user distributes the downloaded work or an infringing derivative. But in the latter case as well, there isn't infringement until the user distributes something relating to the output. Don't confuse my claim with "it's not illegal if no one finds out". If you make a movie adaptation out of someone else's book without permission, you aren't committing copyright infringement unless and until you actually distribute or show your movie adaptation to someone!

My general point is that you can't treat the model's mere ability to infringe on copyright as justification to make the model or the model maker (rather than additionally or only a user of the model) liable for infringing outputs. To regulate a particular AI model in a way that preserves freedom of expression, you would have to demonstrate that the model consistently produces infringing outputs X percent of the time when given prompts which don't reference a person/group, a copyrightable work, or a characteristic/style strongly associated with a person/group. I don't know what X percent should be either, but surely 1% is not sufficient.