On 11/9/06, Erik Moeller <erik(a)wikimedia.org> wrote: True, but thats immaterial if someone else manages to monopolize control of the only copies of the original (free) work. There are a great many public domain audio recordings locked away for which only copyrighted 'remastered' versions are available. The same is also true with sheet music. There are some old scores where the original now public domain orchestrations are nearly impossible to obtain, and yet you can buy copyrighted versions at any music store. (Contact the mutopia folks if you don't want to take my word for it, http://www.mutopiaproject.org/ ) We'd like to think this is less likely to happen in the digital world, but there is no real evidence that this will be the case. Although it's easier to copy and preserve a unit of information there is much more information that needs to be preserved. Who outside of the employ of Wikimedia has a current copy of all the commons images? (Jeff? anyone else?) Because we haven't done a dump in nearly 1 year it's hard to get all of them (must spider). Who even has the year old image dump other than me (it's 300gb)? I don't think it's inconceivable that we could have a serious failure (chopper flies into datacenter? :) ) which results in some number of images being lost. At that point, I could take my copies of the non-copyleft material and make some them unfree through various means. Also, with the legal enforcement (DMCA) of technological copyright wrappers it is even conceivable that a PD work can become unfree without first falling out of circulation. Is a work free if it can only be redistributed after someone has been brought up on criminal charges and jailed for removing it from its wrapper? The first point I made is real and is already happening, it wouldn't be unfair to call it common.. the second point depends a little on speculation regarding the willingness of the courts to enforce DMCA like laws in violation of we would consider common sense, but the current trends are not positive. So I think it's clear that copylefts have merit even without considering derivative works. It might be interesting if a half-copyleft existed, whereby you could create non-free derivative works but you always had to include a copy or an offer to provide a copy of the original free work under its original free license. This would close my concerns about non-copyleft content being locked up without taking the step of encumbering derivatives which is opposed by some (generally people who advocate "PD" on Wikimedia projects, or people who advocate BSD licenses in the software world). That said, there is already enough lack of clarity.. and the last thing the world needs is another license or, worse, another confusing CC-foobar modifier.