Thanks to Chad for the chat session where we went through some of the issues. I agree with Chad on some issues, disagree on others, but can now at least see where Chad's coming from.
My own inclination is that we shouldn't let the best be the enemy of the good.
The best fit questions to our site are those which explicitly ask about the sustainability of X or Y.
Good-fit questions ask about topics which have a strong connection to sustainability, for those who know the topic well enough.
And the challenge is that the strength of connection, as well as what sustainability actually is, are to a degree each subjective judgements.
For those of who've been working in related fields, or studying there, or volunteering there, we each have some pretty clear ideas, from lots of exposure, about what does and does not relate to sustainability. The foggy area comes, because we don't have identical ideas.
But, after several decades of active discussion about sustainability, there are quite a few recurring issues: recycling, biodiversity, decarbonisation, pollution, energy efficiency. Those of us who've been working in these fields, take for granted that we don't need to draw the links between each of them and sustainability, each time we use them. And I agree with Chad that none of these are synonymous with sustainability. For example, once all our energy is from renewables, then energy efficiency may not be a meaningful sustainability question (but ISTM that until that time, it is).
Chad makes the very valid point that not all recycling is sustainable; not all decarbonisation is sustainable. Tackling catastrophic climate change is necessary, but not sufficient, for sustainability.
Here's my proposal for how to untangle all this
- During the early months of this site, let's be generous in what we take to be on-topic, to enable us to build momentum and our user base: it's much easier to start broad and then narrow down, than the other way around. Stack Overflow itself followed that path, as have several other Stack Exchanges.
- Let's have a set of definitive questions on the main site that explicitly seek to draw out the relationship between individual topics, and sustainability - one for recycling, one for decarbonisation, one for biodiversity, one for energy efficiency, and so on. We already have a question on pollution and sustainability, and although the question body maybe needs some work, the question title is great: How are pollution and sustainability related?. Model answers should define where the overlap is, as well as where something might be within the individual topic, but actually contradicting sustainability; an example of such a contradiction is demonstrated in the question on the relative "sustainability" of petrol (gasoline) and diesel.
- Let's be tolerant of our differing views of what sustainability means, while being vigilant against pseudo-science and quackery