If we focus on "scientific" evidence, does that leave out other kinds of policy-relevant evidence? Making it non-specific allows disputes over e.g., financial evidence, legal evidence, etc. The standard may be different for these other types of evidence, but agreement on them as "fact" is a basic foundation of policy deliberation. 

(On a side note - this is the first pull request [because it's the first pull request of any substance] where I've replied with a comment instead of just merging the change.  So it raises an interesting procedural question, with a number of options:
- you can re-submit the pull request with a comment to the effect of "I think it should be as I originally stated it". I would then merge the change with a note saying "for further discussion"
- you can re-submit the pull request with the "scientific" part removed (essentially agreeing with my comment),
- you can retract the pull request. 

As I say, this is interesting procedurally - as well as an interesting question for the content of the paper. So bear with me while we sort this out. And it will be useful–figuring out how to do this, and observing how we figured it out, will become part of the ".evidence" for the second paper.