[OSM-talk] Licence of Facebook's derived road datasets? ODbL?

[Christoph Hormann]

(Deliberately replying to myself since this is not meant as a reply to 
anyone specifically)

If i try for a moment to ignore the fact that this matter has 
significant meaning for the OSM community and its social cohesion (the 
social contract between mappers and data users etc.) this is actually a 
quite interesting sociological experiment.

Because the basis of most comments made does not seem to be the desire 
to neutrally assess the situation Rory presents here and its 
implications.  This would usually go by considering what if Rory is 
right and data productions like this would be subject to the ODbL as 
well as the other way round by considering what if Rory is wrong and 
you could distribute data sets like this under any license you want.

What it seems instead happens here is that people look at the situation 
and develop a spontaneous reaction in terms of "should this be possible 
or not" and then specifically search for ways to argue in support of 
this opinion.  This in my experience is how at least 2/3 of all 
discussions in OSM on legal questions happen meanwhile.  This is very 
non-productive and annoying because it results in what is essentially a 
negotiation between different interests presented in the discussion 
instead of actual knowledge and insight into the matter (Erkenntniss in 
German) as it would result from the scientific approach (i.e. making a 
hypothesis and scrutinizing it with scepticism).

I am not really interested in participating in this kind of interest 
negotiation - because (a) the results do not depend on who has the best 
arguments but on who can invest the most time and manpower into the 
discussion and (b) the results would not actually be an objectively 
better or more accurate understanding of the situation.

From an engineering perspective the idea that adding OSM data can create 
a derivative database but subtracting OSM data cannot does not hold up 
of course.  I can create a polygon data set of the Earth surface (a 
simple rectangle in EPSG:4326) and subtract an OSM derived data set of 
the Earth land masses from that to get a data set of the oceans.  
According to the hypothesis this would not be subject to the ODbL.

This realization (of there being no fundamental difference between 
subtracting and adding) is - as Rory already explained - not dependent 
on specific details of the ODbL or the law but derives from elementary 
logic.

-- 
Christoph Hormann
http://www.imagico.de/