GPLv2+ means you are accepting the terms of GPLv5. What's in GPLv5? I have no idea. No one has any idea. It might never get written. As long as RMS is in charge, I'm not worried about the contents of the next GPL dramatically differing from the current spirit.
However, there is no guarantee that I will agree with future versions of the GPL. I'd like to judge them as they come. It's actually really strange to sign up for an open ended contract where a 3rd party is writing the revisions.
> As long as RMS is in charge, I'm not worried about the contents of the next GPL dramatically differing from the current spirit.
You don't have to trust RMS. You can trust lawyers interpreting clause 14 of GPLv3 correctly. This clause says that later GPL versions must be "similar in spirit". It also says that newer versions cannot impose any more obligations or restrictions on authors or copyright holders.
> But what if you objection to GPLv2+ is specifically already realized in GPLv3,like, say, the market-differentiated anti-Tivoization rules.
Yeah, if you like tivoisation, you probably don't like the spirit of the GPL at all. Tivoisation is really a loophole that wasn't anticipated in GPLv2. It should not have been allowed by GPLv2, but it simply wasn't anticipated.
> (Also, "similar in spirit" is so vague as to be completely meaningless.)
Vague is how the law is. It has to be vague, and the people who wrote the GPL have a good understanding of how judges interpret vague language. I trust them to have done a good job.
[...] the GNU General Public License is intended to guarantee your
freedom to share and change all versions of a program--to make
sure it remains free software for all its users.
No, vagueness of the level of that GPL phrase isn't how the law is, and, in fact, vagueness can make a law, contract, or, e.g., license provision devoid of legal effect.
The framework for how judges operate, and the framework for contract law is quite different. Judges has quite a lot of agency and mobility to make common sense decisions. Contract law on other hand must be more rigid, and is designed around making the market more stable and secure.
In a copyright infringement case, a judge would look at license text and make a decision about its meaning. The lawyers would likely try to interpret "similar in spirit" by providing defining points from previous licenses, which a judgment can be based on. How much we trust such decision thus rest on our believes that judges in general can make a reasonable judgment.
> The framework for how judges operate, and the framework for contract law is quite different.
Only in that the latter is a proper subset of the former; more relevantly, in US law, explicit licenses (even gratuitous ones) are applied under contract law principles, so the framework for how judges operate with them is the same as for contracts.
> How much we trust such decision thus rest on our believes that judges in general can make a reasonable judgment.
No, it rests on how much we trust that and also trust that the only reasonable judgement based on the vague text is one that we would prefer.
However, there is no guarantee that I will agree with future versions of the GPL. I'd like to judge them as they come. It's actually really strange to sign up for an open ended contract where a 3rd party is writing the revisions.