[cc-licenses] Most important feature: GPL-compatibility

drew Roberts zotz at 100jamz.com
Tue Jan 10 13:28:28 EST 2012

On Friday 06 January 2012 22:05:21 David Chart wrote:
> I don't think allowing conversion to the GPL is a good idea, and I don't
> think that GPL compatibility is possible.

It may not be, but there is a need for it.
> On the philosophical point, if the GPL can already be used for any creative
> works, then there is no need for a CC license doing the same thing.

There is a need for all copyleft Free works to be mixable. It may not be 
possible. It likely isn't possible in all cases, but it is needed.

> The 
> claim that a truly free work must come with the source is thus not relevant
> to the question of how the CC licenses should be revised.

This statement can't really be evaluated properly until we can properly define 
source for all cases. So far, I have seen no serious attempts to do this.

> The argument must 
> be that it is, in general terms, a good idea for CC-BY-SA works to be also
> licensable under the GPL.

I don't think they should be. I want my BY-SA works to be able to be used 
alongside or perhaps even mixed with GPL works (mine or others) but I don't 
want them to be able to be put under the GPL. (Perhaps I am being stupid 
here, I am certainly open to reasoned arguments on the issue.)
> I think it would be a bad idea to allow works currently licensed under
> CC-BY-SA to be relicensed under the GPL. The authors releasing those works
> could have released them under the GPL, but chose not to. Having CC change
> that decision for them without consultation would be politically dangerous,
> I fear; a lot of people would start suggesting that you can't trust the CC
> not to issue version 5.0 with a clause saying "Google can use this stuff
> however it likes under any licence". (Google promises not be evil, so
> that's OK, right?)
> More practically, I don't think it's actually *possible* to distribute a
> wide range of BY-SA works under the GPL. 3.0 defines source code, and
> clause 6 says that when you convey an object form (not the source), you
> must convey machine-readable Corresponding Source. For a fair number of
> works that BY-SA might be used for, the preferred form for modifications is
> not machine-readable. The GPL simply doesn't apply. The source must also be
> in a publicly-documented format with an available source code
> implementation. Even for electronic works, this is often not the case;
> artists who work in Photoshop, for example, cannot provide the preferred
> form for modifications in such a format, because the preferred form for
> modifications is a Photoshop file.
> I also strongly doubt that you can get away with saying "whatever we have
> is the source code"; the language looks designed to exclude the binary
> blobs that come with some hardware. In that case, a conversion clause is
> meaningless; you cannot distribute under the terms of the GPL, because you
> cannot hold to those terms. (A conversion clause would provide no leverage
> to get the original creator to provide the source; if someone holds
> copyright, says that they are releasing something under the GPL, but fails
> to provide source, they have merely failed to release something under the
> GPL. Barring other contracts, they have no obligation to succeed.)

I don't buy this and I think it may be a dangerous argument. If I release a 
program I wrote in binary form and do not release the source but put the 
program under the GPL, it is under the GPL. Since no one else holds 
copyrights to the program, no one can force me to give them source (perhaps a 
weakness of copyright law?) but they can make copies for themselves, they can 
rewrite it and release that source when they distribute the new executable.
> I can see that it is inconvenient for video games, and that the original
> intent of the artists almost certainly was for the images to be usable in
> any video game, but I don't think that problem should be solved by changing
> the license. Instead, you should get the works relicensed (should be no
> problem if the artists really did mean that),

No, it is a problem. The artists may have passed on. They may have gone off of 
Free licensing their works. They may be like me and want their BY-SA works to 
be usable alongside GPL works but not want them under the GPL for one reason 
or another.

If some innovative thinking can solve this problem, we will all be better off 
for it.

> or rewrite the code so that 
> you can use artwork released under a different license, even a non-free
> one. I'm well aware that neither of those, particularly the second, is a
> trivial task...

all the best,


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