Saluton ĉiuj,

I forward here the message I initially posted on the Meta Tremendous Wiktionary User Group talk page, because I'm interested to have a wider feedback of the community on this point. Whether you think that my view is completely misguided or that I might have a few relevant points, I'm extremely interested to know it, so please be bold.

Before you consider digging further in this reading, keep in mind that I stay convinced that Wikidata is a wonderful project and I wish it a bright future full of even more amazing things than what it already brung so far. My sole concern is really a license issue.

Bellow is a copy/paste of the above linked message:

Thank you Lydia Pintscher for taking the time to answer. Unfortunately this answer miss too many important points to solve all concerns which have been raised.

Notably, there is still no beginning of hint in it about where the decision of using CC0 exclusively for Wikidata came from. But as this inquiry on the topic advance, an answer is emerging from it. It seems that Wikidata choice toward CC0 was heavily influenced by Denny Vrandečić, who – to make it short – is now working in the Google Knowledge Graph team. Also it worth noting that Google funded a quarter of the initial development work. Another quarter came from the Gordon and Betty Moore Foundation, established by Intel co-founder. And half the money came from Microsoft co-founder Paul Allen's Institute for Artificial Intelligence (AI2)[1]. To state it shortly in a conspirational fashion, Wikidata is the puppet trojan horse of big tech hegemonic companies into the realm of Wikimedia. For a less tragic, more argumentative version, please see the research project (work in progress, only chapter 1 is in good enough shape, and it's only available in French so far). Some proofs that this claim is completely wrong are welcome, as it would be great that in fact that was the community that was the driving force behind this single license choice and that it is the best choice for its future, not the future of giant tech companies. This would be a great contribution to bring such a happy light on this subject, so we can all let this issue alone and go back contributing in more interesting topics.

Now let's examine the thoughts proposed by Lydia.

Wikidata is here to give more people more access to more knowledge.
So far, it makes it matches Wikimedia movement stated goal.
This means we want our data to be used as widely as possible.
Sure, as long as it rhymes with equity. As in Our strategic direction: Service and Equity. Just like we want freedom for everybody as widely as possible. That is, starting where it confirms each others freedom. Because under this level, freedom of one is murder and slavery of others.
CC-0 is one step towards that.
That's a thesis, you can propose to defend it but no one have to agree without some convincing proof.
Data is different from many other things we produce in Wikimedia in that it is aggregated, combined, mashed-up, filtered, and so on much more extensively.
No it's not. From a data processing point of view, everything is data. Whether it's stored in a wikisyntax, in a relational database or engraved in stone only have a commodity side effect. Whether it's a random stream of bit generated by a dumb chipset or some encoded prose of Shakespeare make no difference. So from this point of view, no, what Wikidata store is not different from what is produced anywhere else in Wikimedia projects.
Sure, the way it's structured does extremely ease many things. But this is not because it's data, when elsewhere there would be no data. It's because it enforce data to be stored in a way that ease aggregation, combination, mashing-up, filtering and so on.
Our data lives from being able to write queries over millions of statements, putting it into a mobile app, visualizing parts of it on a map and much more.
Sure. It also lives from being curated from millions[2] of benevolent contributors, or it would be just a useless pile of random bytes.
This means, if we require attribution, in a huge number of cases attribution would need to go back to potentially millions of editors and sources (even if that data is not visible in the end result but only helped to get the result).
No, it doesn't mean that.
First let's recall a few basics as it seems the whole answer makes confusion between attribution and distribution of contributions under the same license as the original. Attribution is crucial for traceability and so for reliable and trusted knowledge that we are targeting within the Wikimedia movement. The "same license" is the sole legal guaranty of equity contributors have. That's it, trusted knowledge and equity are requirements for the Wikimedia movement goals. That means withdrawing this requirements is withdrawing this goals.
Now, what would be the additional cost of storing sources in Wikidata? Well, zero cost. Actually, it's already here as the "reference" attribute is part of the Wikibase item structure. So attribution is not a problem, you don't have to put it in front of your derived work, just look at a Wikipedia article: until you go to history, you have zero attribution visible, and it's ok. It's also have probably zero or negligible computing cost, as it doesn't have to be included in all computations, it just need to be retrievable on demand.
What would be the additional cost of storing licenses for each item based on its source? Well, adding a license attribute might help, but actually if your reference is a work item, I guess it might comes with a "license" statement, so zero additional cost. Now for letting user specify under which free licenses they publish their work, that would just require an additional attribute, a ridiculous weight when balanced with equity concerns it resolves.
Could that prevent some uses for some actors? Yes, that's actually the point, preventing abuse of those who doesn't want to act equitably. For all other actors a "distribute under same condition" is fine.
This is potentially computationally hard to do and and depending on where the data is used very inconvenient (think of a map with hundreds of data points in a mobile app).
OpenStreetMap which use ODbL, a copyleft attributive license, do exactly that too, doesn't it? By the way, allowing a license by item would enable to include OpenStreetMap data in WikiData, which is currently impossible due to the CC0 single license policy of the project. Too bad, it could be so useful to have this data accessible for Wikimedia projects, but who cares?
This is a burden on our re-users that I do not want to impose on them.
Wait, which re-users? Surely one might expect that Wikidata would care first of re-users which are in the phase with Wikimedia goal, so surely needs of Wikimedia community in particular and Free/Libre Culture in general should be considered. Do this re-users would be penalized by a copyleft license? Surely no, or they wouldn't use it extensively as they do. So who are this re-users for who it's thought preferable, without consulting the community, to not annoy with questions of equity and traceability?
It would make it significantly harder to re-use our data and be in direct conflict with our goal of spreading knowledge.
No, technically it would be just as easy as punching a button on a computer to do that rather than this. What is in direct conflict with our clearly stated goals emerging from the 2017 community consultation is going against equity and traceability. You propose to discard both to satisfy exogenous demands which should have next to no weight in decision impacting so deeply the future of our community.
Whether data can be protected in this way at all or not depends on the jurisdiction we are talking about. See this Wikilegal on on database rights for more details.
It says basically that it's applicable in United States and Europe on different legal bases and extents. And for the rest of the world, it doesn't say it doesn't say nothing can apply, it states nothing.
So even if we would have decided to require attribution it would only be enforceable in some jurisdictions.
What kind of logic is that? Maybe it might not be applicable in some country, so let's withdraw the few rights we have.
Ambiguity, when it comes to legal matters, also unfortunately often means that people refrain from what they want to to for fear of legal repercussions. This is directly in conflict with our goal of spreading knowledge.
Economic inequality, social inequity and legal imbalance might also refrain people from doing what they want, as they fear practical repercussions. CC0 strengthen this discrimination factors by enforcing people to withdraw the few rights they have to weight against the growing asymmetry that social structures are concomitantly building. So CC0 as unique license choice is in direct conflict with our goal of equitably spreading knowledge.
Also it seems like this statement suggest that releasing our contributions only under CC0 is the sole solution to diminish legal doubts. Actually any well written license would do an equal job regarding this point, including many copyleft licenses out there. So while associate a clear license to each data item might indeed diminish legal uncertainty, it's not an argument at all for enforcing CC0 as sole license available to contributors.
Moreover, just putting a license side by side with a work does not ensure that the person who made the association was legally allowed to do so. To have a better confidence in the legitimacy of a statement that a work is covered by a certain license, there is once again a traceability requirement. For example, Wikidata currently include many items which were imported from misc. Wikipedia versions, and claim that the derived work obtained – a set of items and statements – is under CC0. That is a hugely doubtful statement and it alarmingly looks like license laundering. This is true for Wikipedia, but it's also true for any source on which a large scale extraction and import are operated, whether through bots or crowd sourcing.
So the Wikidata project is currently extremely misplaced to give lessons on legal ambiguity, as it heavily plays with legal blur and the hope that its shady practises won't fall under too much scrutiny.
Licenses that require attribution are often used as a way to try to make it harder for big companies to profit from openly available resources.
No there are not. They are used as a way to try to make it harder for big companies to profit from openly available resources in inequitable manners. That's completely different. Copyleft licenses give the same rights to big companies and individuals in a manner that lower socio-economic inequalities which disproportionally advantage the former.
The thing is there seems to be no indication of this working.
Because it's not trying to enforce what you pretend, so of course it's not working for this goal. But for the goal that copyleft licenses aims at, there are clear evidences that yes it works.
Big companies have the legal and engineering resources to handle both the legal minefield and the technical hurdles easily.
There is no pitfall in copyleft licenses. Using war material analogy is disrespectful. That's true that copyleft licenses might come with some constraints that non-copyleft free licenses don't have, but that the price for fostering equity. And it's a low price, that even individuals can manage, it might require a very little extra time on legal considerations, but on the other hand using the free work is an immensely vast gain that worth it. In Why you shouldn't use the Lesser GPL for your next library is stated proprietary software developers have the advantage of money; free software developers need to make advantages for each other. This might be generalised as big companies have the advantage of money; free/libre culture contributors need to make advantages for each other. So at odd with what pretend this fallacious claims against copyleft licenses, they are not a "minefield and the technical hurdles" that only big companies can handle. All the more, let's recall who financed the initial development of Wikidata: only actors which are related to big companies.
Who it is really hurting is the smaller start-up, institution or hacker who can not deal with it.
If this statement is about copyleft licenses, then this is just plainly false. Smaller actors have more to gain in preserving mutual benefit of the common ecosystem that a copyleft license fosters.
With Wikidata we are making structured data about the world available for everyone.
And that's great. But that doesn't require CC0 as sole license to be achieved.
We are leveling the playing field to give those who currently don’t have access to the knowledge graphs of the big companies a chance to build something amazing.
And that's great. But that doesn't require CC0 as sole license. Actually CC0 makes it a less sustainable project on this point, as it allows unfair actors to take it all, add some interesting added value that our community can not afford, reach/reinforce an hegemonic position in the ecosystem with their own closed solution. And, ta ta, Wikidata can be discontinued quietly, just like Google did with the defunct Freebase which was CC-BY-SA before they bought the company that was running it, and after they imported it under CC0 in Wikidata as a new attempt to gather a larger community of free curators. And when it will have performed license laundering of all Wikimedia projects works with shady mass extract and import, Wikimedia can disappear as well. Of course big companies benefits more of this possibilities than actors with smaller financial support and no hegemonic position.
Thereby we are helping more people get access to knowledge from more places than just the few big ones.
No, with CC0 you are certainly helping big companies to reinforce their position in which they can distribute information manipulated as they wish, without consideration for traceability and equity considerations. Allowing contributors to also use copyleft licenses would be far more effective to collect and use different forms of free, trusted knowledge that focus efforts on the knowledge and communities that have been left out by structures of power and privilege, as stated in Our strategic direction: Service and Equity.
CC-0 is becoming more and more common.
Just like economic inequality. But that is not what we are aiming to foster in the Wikimedia movement.
Many organisations are releasing their data under CC-0 and are happy with the experience. Among them are the European Union, Europeana, the National Library of Sweden and the Metropolitan Museum of Modern Arts.
Good for them. But they are not the Wikimedia community, they have their own goals and plan to be sustainable that does not necessarily meet what our community can follow. Different contexts require different means. States and their institutions can count on tax revenue, and if taxpayers ends up in public domain works, that's great and seems fair. States are rarely threatened by companies, they have legal lever to pressure that kind of entity, although conflict of interest and lobbying can of course mitigate this statement.
Importing that kind of data with proper attribution and license is fine, be it CC0 or any other free license. But that's not an argument in favour of enforcing on benevolent a systematic withdraw of all their rights as single option to contribute.
All this being said we do encourage all re-users of our data to give attribution to Wikidata because we believe it is in the interest of all parties involved.
That's it, zero legal hope of equity.
And our experience shows that many of our re-users do give credit to Wikidata even if they are not forced to.
Experience also show that some prominent actors like Google won't credit the Wikimedia community anymore when generating directly answer based on, inter alia, information coming from Wikidata, which is itself performing license laundering of Wikipedia data.
Are there no downsides to this? No, of course not. Some people chose not to participate, some data can't be imported and some re-users do not attribute us. But the benefits I have seen over the years for Wikidata and the larger open knowledge ecosystem far outweigh them.
This should at least backed with some solid statistics that it had a positive impact in term of audience and contribution in Wikimedia project as a whole. Maybe the introduction of Wikidata did have a positive effect on the evolution of total number of contributors, or maybe so far it has no significant correlative effect, or maybe it is correlative with a decrease of the total number of active contributors. Some plots would be interesting here. Mere personal feelings of benefits and hindrances means nothing here, mine included of course.
Plus, there is not even the beginning of an attempt to A/B test with a second Wikibase instant that allow users to select which licenses its contributions are released under, so there is no possible way to state anything backed on relevant comparison. The fact that they are some people satisfied with the current state of things doesn't mean they would not be even more satisfied with a more equitable solution that allows contributors to chose a free license set for their publications. All the more this is all about the sustainability and fostering of our community and reaching its goals, not immediate feeling of satisfaction for some people.

Once again, I recall this is not a manifesto against Wikidata. The motivation behind this message is a hope that one day one might participate in Wikidata with the same respect for equity and traceability that is granted in other Wikimedia projects.

Kun multe da vikiamo,
mathieu