> The goal of companies creating these LLMs is to supersede the use of source material they draw from, like books.

Nobody is going to stop buying Harry Potter books because they can get an LLM to spit out ~50 words from one of the books. The proportionality factor is very clearly relevant here.

> If LLM companies are allowed to produce market substitutes of original works

Did Meta publish a book written by an LLM?

> The goal of copyright, under US law, is "To promote the progress of science and useful arts".

I would consider training LLMs to be very much in line with those goals.

Quoting Judge Alsup from his recent ruling in Bartz v. Anthropic.

> Instead, Authors contend generically that training LLMs will result in an explosion of works competing with their works — such as by creating alternative summaries of factual events, alternative examples of compelling writing about fictional events, and so on. This order assumes that is so (Opp. 22–23 (citing, e.g., Opp. Exh. 38)). But Authors’ complaint is no different than it would be if they complained that training schoolchildren to write well would result in an explosion of competing works. This is not the kind of competitive or creative displacement that concerns the Copyright Act. The Act seeks to advance original works of authorship, not to protect authors against competition.