Meta sites across the SE network — just meta sites, not regular ones — should start awarding a badge for any post that meets both of the following criteria:
- earns fifteen or more upvotes
- earns fifteen or more downvotes
These criteria indicate problematic posts on normal SE sites, where votes are cast based on post quality. On Meta sites, though, votes indicate level of agreement, and such posts are generally suggestions that people are conflicted on. In practice, they tend to lead to good, insightful explanations of how the sites work or why certain changes should/shouldn't be made. To back this up, I ran a SEDE query1 to find questions that meet the criteria on SO and on MSO.
Open issues: I found that setting the criteria at five upvotes/five downvotes let too many poor posts through, but 15/15 might be too restrictive; we'll have to do some tweaking on the exact numbers to use. I'm also not sure whether we should limit this to questions or make it available for answers as well.
Obligatory suggestions for name and grade: "Controversial"2 or "Insightful"; silver.
EDIT to reply to comments/answers:
The "false positives" problem that Cody mentioned is a real one. I attempted to address it by raising the criteria to 15 votes each way instead of five, but there certainly could be better metrics... a minimum of one massively upvoted answer, perhaps? I'm confident that we can find something with a decent signal-to-noise ratio with some trial and error.
The name of the badge definitely needs work. As dmckee said, we shouldn't be giving the impression that we're actively encouraging controversy. "Controversial" is merely an objective description for posts that correlate with (if not cause) insightfulness, and insightfulness is the real goal.
1: I was unable to generate the query myself; it was [contributed by Andriy M](https://stackoverflow.com/questions/6986461/how-can-i-use-two-sede-sql-queries-as-the-inputs-for-a-third-query/6988200#6988200). 2: While asking this question, I discovered that there have been two requests for controversy badges before. One was [for Area 51](https://meta.stackexchange.com/questions/52185/can-we-have-a-badge-for-controversy-on-area51) and the other was [for regular sites](https://meta.stackexchange.com/questions/34543/can-we-have-a-badge-for-controversy).
With that in mind, "Insightful" might be the superior name. More likely, there's some third, even better term out there that I haven't thought of yet. Lance described target posts as thought-provoking, so how about "Provocative" or "Intriguing"?