[OSM-talk] Ground truth for non-physical objects

Christoph Hormann osm at imagico.de
Sat Dec 15 15:57:57 UTC 2018

On Saturday 15 December 2018, Colin Smale wrote:
> "without access to the same sources" ... what if there is only one
> source of truth? With these non-observable items like admin
> boundaries that is often the case. Does "independent verifiability"
> now mean that there must be at least two sources that agree before
> this criterion is fulfilled? What qualifies as a source, anyway? If
> two people look at the same tree, is that one source or two? Such
> observations are always ephemeral anyway.

Independent verifiability means exactly what it says - that anyone needs 
to be able to independently verify if a statement is true or false 
based on observations of the geographic reality.  If you think about it 
in terms of sources you are either on a completely wrong track in terms 
of understanding the fundamental concept of verifiability or you are 
specifically thinking about things outside the domain of verifiable 

Verifiability of administrative boundaries varies but most national 
(admin_level=2) land boundaries are verifiable.

> The link to your blog was useful, thanks. I will read through it all
> later, but my immediate reaction was that it is not a good idea to
> have parallel fora, especially when discussing something as
> fundamental as this. Either we do it here on the ML, or on your blog
> post, or on the OSM wiki; but please, not in three places at once.

The blog post was written before this discussion started here.  I 
included the link to not unecessarily have to repeat myself in the 

Christoph Hormann

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