As you point out, I'm not sure how you would do that study without having two otherwise identical countries that differ only by copywrite law. Still, we can ma

As you point out, I'm not sure how you would do that study without having two otherwise identical countries that differ only by copywrite law. Still, we can make some guesses what would happen without copyright. eBook readers could offer all books for free to improve sales of their reader. Amazon already gives books that are in the public domain for free on Kindle. If Amazon doesn't expand this to all books, some competitor will. Project Gutenberg would also expand their collection to include all books. Physical books wouldn't be free, but there would be no guarantee the author would get any money from them. There'd be zero incentive for printing houses to pay authors. They'd be allowed to sell the books without the author's permission and keep all the profits. Authors' best option may be to ask for donations or start a Patreon. This works for some people, but in general, you make orders of magnitude less money off donations than actually selling something. Would less money going to authors stop people from writing books? Probably somewhat. The most popular authors will still have ways to make money. And there'd still be people who write books for free, as a hobby. But it would reduce the number of professional authors.