I see a lot of questions along the lines of "what would be the impact if X happened?" These seem to me to be skirting the edge of on-topic, even for our blessédly open-minded Worldbuilding site. So I'd like to understand: what makes such a question good. What makes such a question worth answering, and not worth closing?
Here are a few examples:
- If the earth gradually stopped spinning, what would the changes look like in 20 years?
- How will our world change if all men suddenly die? (and similar for the XX half of humanity)
- What would happen to a medieval town that suddenly has no industry?
- What would happen if magnets stopped working?
- What would happen if electricity stopped working?
- Time no longer passes except near intelligent creatures, how does the world continue?
Most of the above are a slightly more specific flavor than what I had in mind, these are mostly "what would happen if tomorrow something changed." But I'm also interested in "how would the world be different if it was (always) just like ours except for X?" Like these:
- Could an ocean be saturated with something other than salt?
- What if every animal as large as, or larger than, a horse, went extinct during the last Ice Age?
- How would a world with an extremely high water level and only a small land mass differ from Earth?
One solid point, mentioned here, is that a good question should have clear criteria for what makes a good answer. What else should one consider before asking "what would happen if left-handed red-heads started getting super powers on their 33rd birthdays?"