The problems I see with this concept is similar to what I have on IG's notability guide, in that you describe the concept you're going for, have a list of examples, but skipped over having a clear, objective ruleset. Aside from that, I see three larger issues with the concept right now:
- The scale that's been put down is a linear scale from 1-9 for left and right wing, when the political compass is actually two dimensional.
- The scale in its current form only applies to human politics, and can't be applied very widely to any other subjects I can think of.
- The scale seems to be viewed through the lens of US politics, which means that the definitions of "far left" and "far right" is based on that. It's generally understood that what's considered "far right" in the United States is considered completely insane in something like UK politics, and what's considered "far right" in the UK is more like the middle, in the US.
Also, on Wikipedia, back before any of these political problems arose, there was actually another type of relativity problem in article writing: Americentrism. As a galactic platform, I have to admit that it's my hope that relativity issues based on country, rather than politics, is also addressed.
We're going to have general guidelines and expect people to abide sensibly by them. If they won't, we'll get rid of them without hesitation. We're not going to repeat Wikipedia's observable errors. Wikipedia destroyed itself through allowing its community culture to devolve into a collection of constantly quibbling rules lawyers that drove all the sensible people away. Second, your issues are largely misplaced.
- The Pournelle Chart may be popular among political geeks, but it is hardly definitive. More importantly, it does not lend itself to a simple interface that will not confuse the average user. The more we discussed the issue, the more it became obvious that a simple 9-level setting would suffice. Look through the Wikipedia histories. There aren't THAT many competing perspectives; three might actually be enough. Nine was our compromise between 5 and 99. We can easily increase or decrease it as needed.
- Politics are the primary problem we are attempting to solve. If we can successfully resolve that, all the other perspective differences will be easy by comparison.
- It is not viewed through the scale of US politics, but accounts for the known global spectrum, which extends further to the right in the USA and further to the left in continental Europe. It no more matters what people in the UK think of US politics than what people in Argentina think of Indonesian politics.
That being said, there may well be utility in a fourth slider, Regionality, for certain issues. That would allow for a more substantive page for those familiar with the region, and better summaries for those who are not. But that is an idea best tabled. If the approach works, it can always be extended.
Suggestion, if it isn't already part of the vision for "preference filtering" or somesuch. Make the sliders an instance of a flexible tagging system (think html/xml tags). The sliders would use tags like <Relativity:+7> or <Relativity:-4> indicating that the tagged content would only appear to users who apply Relativity 7 or greater (resp. 4 or less). This keeps the existing design idea, and...
A more generic tagging system would enable filtering of many perspectives that are essentially independent of political considerations. Some examples that could be a spectrum or maybe a 1-of-N choice:
- Economic (Austrian vs. Neo-Keynesian vs. Monetarist)
- Theological (Calvinist vs. Arminian)
Some tags might be applied as a pure binary (yes/no) filter:
- Regional perspectives (e.g. I'm interested in regional info for Iran, Australia, and Central America)
- Consumer information that is only of interest to specific groups (people with allergies, vegans, etc.)
Each page displays any/all perspective options that are present within that page. I think this kind of approach is in the spirit of letting people define and control their own perspectives, and would attract contributors who have differing views that don't fall along political lines. Most importantly I'd just be careful to avoid designs that would preclude this sort of extension in the future, thus the tag idea.