[gnu.org #238740] Derivatives of dual-licensed Creative Commons Attribution-ShareAlike and GFDL works

Evan Prodromou evan at bad.dynu.ca
Thu May 5 13:27:49 EDT 2005

On Thu, May 05, 2005 at 06:08:02PM +0200, Wouter Vanden hove wrote:

> >Unlike other copyleft licenses, the ShareAlike says that the
> >derivative work can be distributed _only_ under the terms of that
> >license (or a later version, or an equivalent iCommons license).
> Unless, permission is granted to them via another license  by the 
> original author.

Yes. My point is that neither the GFDL (I think) nor the CC-by-sa
allows dual-licensed derivative works.

> That's a false assumption. They aren't two works: it's one work,
> >with two optional licenses.
> one version under with two licenses =
> two versions under each one licenses.

I'm afraid I just can't see how granting permission to use a work
under two different licenses makes it into two different works. If I
give you permission to enter my house through either the back door or
the front door, that doesn't mean I have two houses.

> it's not necesaary to talk about derivatives,
> just think about distributing the original dual-licensed work by 
> third-parties.
> According to your own reasoning they always have to remove one license.

Is that supposed to be some kind of /reductio ad absurdum/? Maybe you
should take a closer look at the verbatim copying sections of both
licenses. Do either seem amenable to third parties distributing under
multiple licenses?

I realize that all this dual-licensing stuff seems counterintuitive,
but maybe we should instead be wondering why we would expect two
strong copyleft licenses to work well together in the first place.

Just because you have two good horses, doesn't mean you can ride them
both at the same time, with a foot on each one's back. One may be
taller than the other, or one may run faster than the other. Two
things that work well on their own may not work well together.

I don't think this is a hopeless case, by the way. I think you can do
a careful license grant that routes around the extreme exclusivity of
the two licenses. Maybe something like this: 

	"You may use this work per the terms of the Creative Commons
	Attribution-ShareAlike 2.0 license or, at your option, under
	the terms of GNU Free Documentation License 1.2. As a special
	exception, you may also offer recipients of the work or
	derivative works their choice of either of these two

I don't think it's gruesome; I just think it takes some thought. I
don't see why that's some kind of radical nuthouse idea.


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