[copyleft-next] in defense of the TGPPL idea

Theodore Ts'o tytso at mit.edu
Tue Jul 24 19:17:23 UTC 2012


On Tue, Jul 24, 2012 at 03:07:47PM -0300, Zooko Wilcox-O'Hearn wrote:
> 
> One particular detail of my TGPPL that I value and that I'm not sure
> the TPL provides is that if you take advantage of the permission to
> keep a derived work temporarily proprietary, then this obligates you
> to offer the same permission to people who make worked derived from
> your derived work.

I agree that's definitely a good thing to do.  Keep in mind that what
I proposed as the TPL was a concept, and not something actually that
was actually implemented in terms of creating actual legal text that
could be used in a license.  So I have to give great acknowledgement
to the TGPPL in that it has taken that (non-trivial) step.

> Make sense? So when I publish source code under the TGPPL, I'm not
> offering people the option of making a derived work, keeping it
> proprietary for a limited time, and then releasing it under a strict
> copyleft which disallows others from making time-limited proprietary
> derived works of it. On the other hand, I *am* offering people the
> option of making a derived work, making it Free/Open immediately, and
> disallowing others from making a proprietary derived work from it,
> even for a limited time.

> The latter option is currently the case for Tahoe-LAFS and the other
> software that I release in this way because I offer the recipient the
> choice of GPL or TGPPL. So if you want to make a derived work of
> Tahoe-LAFS without allowing anyone "downstream" of you to make a
> proprietary derivation of your work, even for a limited time, then you
> can do so by releasing your derived work solely under GPL.

Ah, I see.  But after the grace period as expired, does the code in
question become relicensed under "choice of TGPPL and GPL" again?  I
assume it would have to be if the code is to be eligible to be merged
into the original codebase.

> I'm interested in developing a "TGPPLv2" which is expressed as an
> "Additional Permission" to GPL. That would have exactly the same
> consequences as the current TGPPLv1, sketched above, but it would
> probably be better in a lot of ways to have it expressed as an
> "Additional Permission" to GPLv3+.

There are some problems with giving people the power to create
derivitive works under a strict copyleft.  For example, I know that at
least some people are not happy with a GPLv2 or v3 license,
specifically because someone could strip out the GPLv2 license.  The
same is true of adding an additional permission which grants an
exception to the GPLv3 anti-tivoization clause.  Anyone can strip it
out; and that's not necessarily something that the original copyright
holder might not want.

As one example, of the problems this can engender, consider the case
where a project has GPLv3 plus an anti-anti-Tivoization clause, and
then there are some personality issues, and someone decides to fork
the project, and in the process, they relicense the fork under a
strict GPLv3 license, without the anti-Tivo exception clause.  Now the
any contributions that are made to the fork of the project can't be
merged into the original parent project, due to copyright
incompatibility issues; but the child project can always take
contributions made to the parent, and strip out the copyright commit
by commit.  Some might argue that this would be an unfair situation;
it is certainly asymmetric.

> So, I personally believe Free/Open software is a social good that is
> massively, drastically under-produced, just as simple economic theory
> would predict. I think -- or rather I hope -- that a better social
> outcome is possible somewhere in the middle, between the two extremes
> of 0 and ∞. TGPPL is my stab at it. We can't do much worse than we are
> already doing.

Yes, this was exactly my thinking when I made the TPL proposal.

I think I had heard of the TGPPL in passing some time ago, but I had
completely forgotten about it until I read your e-mail --- and so
thank you for writing it, and more importantly, being willing to
experiment "outside of the box" as far as open source licensing
practices are concerned!

       	       	      	   	  	    	      - Ted


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