Hi Andreas,
2016-01-26 13:17 GMT+01:00 Andreas Kolbe jayen466@gmail.com:
In my opinion, Wikidata's CC-0 licence undermines that, because it allows re-users to cut the chain between the end user and the data's original source.
If I understand, you are concerned about verifiability of information in Wikidata. What is completely unclear to me is why you are mixing verifiability and copyright or, in other words, why you think that you can solve the problem of verifiability with copyright.
TL;DR Licenses are for copyright, not verifiability. Using a different license will not solve your verifiability problems.
# Is CC-BY for Wikidata a good idea?
CC-0 or CC-BY (or any license) are based on copyright law. Broadly speaking (but IANAL), "facts" are not copyrightable because they lack originality which is one of the conditions required by copyright law. In this sense, no single statement that you find on Wikidata (e.g. Barack Obama was born on 4 August 1961) is copyrightable.
For collections of facts (i.e. datasets) the situation is much less clear and it is not easy to decide if collection of data/facts are copyrightable at all. The doctrine of the "Sweat of the Brow" [1a][1b] indeed the originality requirement is relaxed and the fact that "skill and labour" was put in creating a collection of data is sufficient to give rise to copyright. This view has been recently rejected in some court cases by the European Court of Justice (see Football Dataco & others v. Yahoo UK ! [2a][2b]) ruling that it is not sufficient to say that putting together a collection of facts required some sort of effort (even quantifiable in monetary terms) to give rise to copyright. In Football Dataco v. Yahoo the dataset consisted in sports event results, but the same applies also to other contexts such as the digitization of (public domain) photographs or OCR of (public domain) texts.
As a Wikimedian, I am more than eager to support the idea that scanned versions of PD photos and texts should remain in the public domain. I do not want to invoke this kind of principle to be able to claim copyright on the Wikidata dataset so to be able to apply the CC-BY license. This is also the position of other projects like Project Gutenberg [3].
On the other hand, in many jurisdictions the moral rights [4] associated with any work, e. g. among other the right of having the paternity of a work attributed, are perpetual and can not be transferred or waived. In fact the CC-0 legal code says: "A Work made available under CC0 may be protected by copyright and related or neighboring rights includ[ing]: moral rights retained by the original author(s) and/or performer(s); database rights; [...]".
So the problem of which is the justification for having Wikidata released under CC-BY remains.
# Licenses and verifiability
Besides the problem above, even if we could use CC-BY and make use of "Sui Generis Database Rights" (see section 4 of CC-BY legal code [5]) I am not sure your verifiability problem would be solved. CC-BY requires the reuser to provide "[...] attribution, in any reasonable manner requested by the Licensor".
This means that I could build a page replicating (part of) Wikidata data, maybe mix them with other sources and the add a link to the bottom of the saying "Data from Wikidata (c) Wikidata contributors CC-BY (+link to the item and item history for author names); source A; source B; ...".
This would completely satisfy the attribution requirement but do little to solve the verifiability problem because, basically, you can not use copyright to force anybody to use a particular design of their website and/or database and maintain the "verifiability chain" for each statement.
To conclude, the verifiability problem is very important for all the projects, but I am very skeptic to the idea that copyright licenses are the means to solve it
C
[1a] https://en.wikipedia.org/wiki/Sweat_of_the_brow [1b] https://meta.wikimedia.org/wiki/Wikilegal/Sweat_of_the_Brow [2a] http://curia.europa.eu/juris/liste.jsf?&num=C-604/10 [2b] http://kluwercopyrightblog.com/2012/03/01/football-dataco-skill-and-labour-i... [3] https://www.gutenberg.org/wiki/Gutenberg:No_Sweat_of_the_Brow_Copyright [4] https://en.wikipedia.org/wiki/Moral_rights [5] https://creativecommons.org/licenses/by/4.0/legalcode