Points 1-4 of my year-ago post, Which counterfactual public domain day? hold up well, but number 5 could be improved: it concerns optimal copyright term, which is a rather narrow issue, and viewed from an unhealthy side.
Instead, consider that in common language, and presumably to most people, “in the public domain” means something like “revealed to the public” or “not secret”, as the first definition currently presented by Google reflects:
public domains, plural
- The state of belonging or being available to the public as a whole
- Not subject to copyright
- the photograph had been in the public domain for 15 years
- public-domain software
- Public land
- a grazing permit on public domain
It’s not clear how Google’s computers selected those definitions, but they did a good job: “intellectual property” focused definitions seem to have largely crowded out the common usage in written down definitions.
The common “available to the public as a whole” understanding reflects why I have been more recently careful to stress that copyright policy is a small part of information policy and that reducing copyright restrictions (anti-sharing regulation), all the way to abolition, are in this broader context moderate reforms — more thoroughgoing reform would have to consider pro-sharing regulation (as I’ve said many times, broadly construed; choose the mechanisms that fit your ideological commitments) — requiring information revelation, eg of computer program source code.
People curating and promoting works not subject to copyrestriction, information preservationists, leakers, transparency activists, and many others provide various sorts of pro-public-domain regulation. But I especially want to recognize enforcers of copyleft regulation as benefiting (though problematically) the commonly understood public domain, and in the most important field (computation is suffusing everything, security through obscurity isn’t, etc).