5 ms·

> Fundamentally, copyleft can only be instantiated once. That's true of GPL-style copyleft, because it was designed quite intentionally to be a network-effect-

> Fundamentally, copyleft can only be instantiated once. That's true of GPL-style copyleft, because it was designed quite intentionally to be a network-effect-leaden singleton. We say "GPL-compatible", but it's more accurate to say "GPL-submissive". The difference was felt very directly by the Eclipse folks in the run up to EPLv2. But there's nothing about share-alike terms that require that stricture. The Parity license that I mention in the blog post takes a different tack. Have a look at its rule about how to contribute back: https://paritylicense.com/versions/7.0.0.html#contribute https://paritylicense.com/versions/7.0.0.html#contribute A developer building on Parity code could choose to license their work on weaker copyleft terms.

naniwaduni 7y ago
> But there's nothing about share-alike terms that require that stricture. The Parity license that I mention in the blog post takes a different tack. But they do. "or another license that allows everything this license does" sounds less restrictive at a glance, in that on the surface it permits additions to be separately licensed, but its effect is the same: no license with more stipulations is acceptable, and by symmetry any less restrictive share-alike license with similar wording cannot accept combination with this one. Additions to code under your license may be published under weaker terms. But they cannot be weaker copyleft terms. I can think of a few edge cases involving use of independent portions of the new work under only the weaker license, but it doesn't achieve a likely goal of someone choosing a copyleft license: to eliminate confusion about whether it's permissible to merge downstream improvements.
- kemitchell 7y ago
  > But they cannot be weaker copyleft terms. Why not? What about, say, the API Copyleft License, which reads very much like Parity, but permits building closed applications? https://apicopyleft.com/ https://apicopyleft.com/ That license allows everything Parity does, plus one more: creating closed applications.
  - naniwaduni 7y ago
    This so-called API Copyleft license is too weak to usefully consider a copyleft license.
    - kemitchell 7y ago
      Do you think the same of MPL? https://spdx.org/licenses/MPL-2.0.html https://spdx.org/licenses/MPL-2.0.html
      - naniwaduni 7y ago
        Taken on its own merits, I would indeed consider MPL 2.0 inadequate as a general-purpose copyleft license. Formally, you could argue that it's even weaker than the API Copyleft terms. As such, it's hard to recommend MPL for a project standing alone. It understands, however, its position as a compromise which makes the underlying goal of its approach to copyleft untenable. Despite that, tries to preserve the ability to incorporate downstream changes through one degree of separation. The difference in expectations is palpable. The implied flow for publishing derivatives of MPL work is to distribute also under MPL, with the option of separately licensing non-Covered Software presented as a concession to tightly define the scope of the license. The implied flow for publishing derivatives of API Copyright Licensed work seems to involve carefully considering how much you can get away with under the listed exceptions, with the option to not share alike presented front and center. The distinction is essentially irrelevant to anyone approaching licensing from a legalistic perspective, bet defaults matter for everyone else.
        kemitchell 7y ago
        The use case for MPL and SSPL was broadly the same: selectively apply permissivity for the primary build-on use case (browser plugins, applications) to stoke adoption and copyleft to other use cases (forks, hosted offerings) as a bulwark against competitors (Microsoft, AWS). In drafting and presentation, I thought SSPL failed to communicate that heritage. So I wrote what became the API Copyleft License.
belorn 7y ago
It is always useful to fall back to basic when ever people try to redefine copyleft or GPL. A copyright license is a list of complex permissions. Nothing more, nothing less. If you have a two set of permissions, compatibility is the logical conclusions of finding intersection and see which actions are permitted in both set. Set theory do not have submissive and dominant sets. The intersection is always the elements which are in both A and B. The parity license says "Make sure every part of the source code is available under this license or another license that allows everything this license does". It practically spells out that permissions in the intersection that lies between parity and an other license is acceptable to use when combining parity with an other license. It is true. It also true for any other copyright license, including GPL.
- hyperpape 7y ago
  Set theory doesn’t, but this isn’t pure set theory, it’s a social process (perhaps it’s game theory, though I don’t think you have to really use math to get the point ). The GPL came first, so it effectively forces others to submit or to go it alone.
  - belorn 7y ago
    Copyright is the entity that came first. A copyright license is the object you can use to claim you have permission to do something which copyright declares illegal by law. We can put gpl first when trying to determine the intersection of all the set of permissions when dealing with multiple licenses, but in the end the fundamental question to be answered is: Do you have a set of permissions to do something which copyright makes illegal. Yes/No. In the case of multiple copyrighted work you need permission for all that which copyright limits in those cases. If we want to look at it from a game theory perspective it we would ask who the agents are, their goals, the environment and the resources. Here a narrow intersection can be a cost, or it can be irrelevant depending on context. The biggest permission is always to write it yourself which make the limitation of copyright a non-issue for the author. Naturally that is not the only factor, nor the only agent, so it all depend.
- kemitchell 7y ago

naniwaduni 7y ago

> But there's nothing about share-alike terms that require that stricture. The Parity license that I mention in the blog post takes a different tack. But they do. "or another license that allows everything this license does" sounds less restrictive at a glance, in that on the surface it permits additions to be separately licensed, but its effect is the same: no license with more stipulations is acceptable, and by symmetry any less restrictive share-alike license with similar wording cannot accept combination with this one. Additions to code under your license may be published under weaker terms. But they cannot be weaker copyleft terms. I can think of a few edge cases involving use of independent portions of the new work under only the weaker license, but it doesn't achieve a likely goal of someone choosing a copyleft license: to eliminate confusion about whether it's permissible to merge downstream improvements.

kemitchell 7y ago
> But they cannot be weaker copyleft terms. Why not? What about, say, the API Copyleft License, which reads very much like Parity, but permits building closed applications? https://apicopyleft.com/ https://apicopyleft.com/ That license allows everything Parity does, plus one more: creating closed applications.
- naniwaduni 7y ago
  This so-called API Copyleft license is too weak to usefully consider a copyleft license.
  - kemitchell 7y ago
    Do you think the same of MPL? https://spdx.org/licenses/MPL-2.0.html https://spdx.org/licenses/MPL-2.0.html
    - naniwaduni 7y ago
      Taken on its own merits, I would indeed consider MPL 2.0 inadequate as a general-purpose copyleft license. Formally, you could argue that it's even weaker than the API Copyleft terms. As such, it's hard to recommend MPL for a project standing alone. It understands, however, its position as a compromise which makes the underlying goal of its approach to copyleft untenable. Despite that, tries to preserve the ability to incorporate downstream changes through one degree of separation. The difference in expectations is palpable. The implied flow for publishing derivatives of MPL work is to distribute also under MPL, with the option of separately licensing non-Covered Software presented as a concession to tightly define the scope of the license. The implied flow for publishing derivatives of API Copyright Licensed work seems to involve carefully considering how much you can get away with under the listed exceptions, with the option to not share alike presented front and center. The distinction is essentially irrelevant to anyone approaching licensing from a legalistic perspective, bet defaults matter for everyone else.
      - kemitchell 7y ago
        The use case for MPL and SSPL was broadly the same: selectively apply permissivity for the primary build-on use case (browser plugins, applications) to stoke adoption and copyleft to other use cases (forks, hosted offerings) as a bulwark against competitors (Microsoft, AWS). In drafting and presentation, I thought SSPL failed to communicate that heritage. So I wrote what became the API Copyleft License.

belorn 7y ago

It is always useful to fall back to basic when ever people try to redefine copyleft or GPL. A copyright license is a list of complex permissions. Nothing more, nothing less. If you have a two set of permissions, compatibility is the logical conclusions of finding intersection and see which actions are permitted in both set. Set theory do not have submissive and dominant sets. The intersection is always the elements which are in both A and B. The parity license says "Make sure every part of the source code is available under this license or another license that allows everything this license does". It practically spells out that permissions in the intersection that lies between parity and an other license is acceptable to use when combining parity with an other license. It is true. It also true for any other copyright license, including GPL.

hyperpape 7y ago
Set theory doesn’t, but this isn’t pure set theory, it’s a social process (perhaps it’s game theory, though I don’t think you have to really use math to get the point ). The GPL came first, so it effectively forces others to submit or to go it alone.
- belorn 7y ago
  Copyright is the entity that came first. A copyright license is the object you can use to claim you have permission to do something which copyright declares illegal by law. We can put gpl first when trying to determine the intersection of all the set of permissions when dealing with multiple licenses, but in the end the fundamental question to be answered is: Do you have a set of permissions to do something which copyright makes illegal. Yes/No. In the case of multiple copyrighted work you need permission for all that which copyright limits in those cases. If we want to look at it from a game theory perspective it we would ask who the agents are, their goals, the environment and the resources. Here a narrow intersection can be a cost, or it can be irrelevant depending on context. The biggest permission is always to write it yourself which make the limitation of copyright a non-issue for the author. Naturally that is not the only factor, nor the only agent, so it all depend.
kemitchell 7y ago