Preamble: what are we trying to accomplish?
The goal here should be to establish guidelines, not hard-and-fast rules. Rules will never cover all cases, and if we devolve into arguing about whether something violates Rule 42, subsection 17, paragraph 6 instead of engaging with the thoughtful users who are actively engaged with this site, we've done something wrong. Seriously wrong.
That said, we cannot simply make it up as we go along or rely on individual whim, because individual whim is highly variable -- one person's reasonable edit is another person's rollback+complaint. Nor can we continue our current practice of addressing a problem by starting a conversation about it that goes on for days or months before being resolved (if it ever is).1 It's unworkable, particularly if we want to grow. Shog9 recently put it this way:
[A]s this community grows it will be less and less feasible to have protracted discussions with each and every author whose posts you edit, and bad habits developed now will start to become painful.
This is particularly true when authors do not return to respond to comments. We need to trust our active users, especially the experienced ones, to improve posts.
What does Stack Exchange already say about editing?
In In Defense of Editing, Jeff Atwood lays out some core values beyond the guidance given in the edit sidebar (and summarized in the question). The whole post is worth reading, but I'm calling out this in particular:
Editing is the backbone of Stack Overflow, and probably (along with the reputation system) one of the single most important distinctions between Stack Overflow and "just another forum".
The Great Edit Wars says more about the philosophy:
Editing is welcomed and encouraged. However, if the author of the post is resistant to your editing changes, even a perfectly legitimate edit based on the above rules, be the bigger man (or woman) and let them have it their way. Our goal here is not to cause friction between users, or to make everything perfect overnight. All we aim to do is gradually clean up and improve questions and answers together.
Conclusion: Constructive edits should generally be offered, and authors are allowed to disagree with them and roll them back. (Nothing is said here about non-authors intervening to roll back edits, by the way.)
Community Manager Grace Note says (excerpting):
- Edits are to improve and fix posts, not to change them.
- Questions must present a problem, answers must present a solution.
- Respect the author's voice and content.
We have rules on content. Offensive language and inappropriate material is not allowed on our sites. You can review our content policy and also keep in mind our rule, "Be Nice". This is not a suggestion, it's a requirement.
Insults, offensive language, and any such should be removed. It is not common that this shows up as anything besides the full content of the post, but in the rare cases that it does, try your best to retain the meaningful content during the removal job.
Conclusion: Editing is not appropriate to remove or change content you merely disagree with. However, editing for insults and offensive language is not only permitted but expected.
Community Manager Shog9 says (excerpting):
The questions you must ask yourself then are:
- Do I understand the answer well enough to edit it?
- Is that paragraph even relevant?
- Can I reword the offensive section to be less offensive while preserving the author's meaning and intent?
Conclusion: Make sure you know what you're doing, don't bother to edit if you should be removing as irrelevant, and, when editing, make the minimal change (reword rather than remove, assuming it's relevant).
So what should we do?
The following seems clear to me from the above (and from common sense, if I may posit such a thing :-) ):
- Merely-distracting material like tangents should be left alone.
- Unsupported and wrong/controversial material should be left alone.
- Except, for the previous two, if content is offensive, it should be addressed with the minimal edit that fixes the problem.
What's "offensive"? We will never be able to formalize a definition of that, and opinions will vary. Since we value site harmony and are trying to build a community, it is my opinion that we should generally err on the side of caution. Most of us let most stuff just go by; if somebody here was offended enough to try to correct a problem, we should have a very good reason to undo that.2 For this reason, while content is in dispute, I think we should leave it edited out, not in, and of course invite the author to address the problem. Anybody who wants to see the original can click one link and get there. And remember that the author can roll back an edit and end the matter; we should place the burden of action on the author of the objectionable material, not on the community.
Ok, but what about strongly-held personal opinion ("doctrine")?
This is an area where we are different from many other SE sites. While I assume there is doctrine on Stack Overflow, DBA, et al, probably nobody there believes that the state of people's immortal souls depends on the outcome of a Stack Exchange post, and also probably nobody feels divinely commanded to spread a particular message. Not so, here.
The participants here will never agree on such values. That's perfectly reasonable. It shouldn't matter. Answers on Stack Exchange aren't about personal opinion. Our problems begin when people assert their opinions as fact, instead of judiciously using phrases like "I believe" or "according to (source)". As soon as somebody says "that means X", someone who disagrees will (necessarily) respond "no it doesn't" (or "no, it means Y"), and pretty soon you have a knife-fight in the comments. This runs counter to our goals of civility and harmony. No good can come of that. And it's so easily avoided.
Consider the following text (drawn from this answer, emphasis mine):
Furthermore, the superiority of the NT model is clearly outlined in the epistle to the Hebrews. Under the Old Covenant only the Levitical priests could "draw near" to God and the penalty for disobedience was death (Nm 18:7, 22). But, now with the New Covenant the Levitical priesthood, the physical temple and its associated tithes, sacrifices and offerings have all been abolished and replaced by the high priesthood of Christ Jesus, His "once for all" perfect sacrifice, and the priesthood of all Christian believers (Heb 7:15-17; 9:11-12, 24-26; 10:19-22; 1 Pt 2:9-10). Thus, the "disannulling" (Heb 7:18) of every ordinance pertaining to the Levitical priesthood and temple service included tithing--its chief means of financial support. Now every Christian believer-priest may "draw near" to God (Heb 7:19, 25; 10:22) through Christ Jesus, our High Priest, wherein we might "come boldly unto the throne of grace, that we may obtain mercy, and find grace to help in time of need" (Heb 4:16).
The paragraph begins with a personal opinion in the form of an unsupported assertion of truth. That weakens the post. Asserting that your scripture is superior to someone else's is not really the behavior we want to encourage here. But it's easily addressed via an edit; instead of saying "the new testament is superior", say "the argument that so-and-so makes for superiority of the NT is...". Additionally, the presumption that Jesus is "our" high priest, on a site that welcomes "Jewish, Christian, Atheist and other viewpoints", is not really the way to go -- but again, it's easily fixed by referring to believers who see Jesus as high priest.
This is the form the edit eventually took. It took five days, after waiting for the author to weigh in. Nobody meant to offend here; we're seeing the effect of unchecked assumptions. It happens a lot here.
At its core, our site will work best if we separate what we believe from how we answer questions. If you want a doctrinal perspective -- if you're looking for Truth -- then you'll find ample help on Christianity.SE, Mi Yodeya, Islam.SE, and Skeptics.SE. Our FAQ describes a religiously-neutral community, one that is focused on the text. In our community of scholars, our individual opinions should be irrelevant. And if they're irrelevant, we shouldn't be espousing them in answers -- that just adds noise. If we nonetheless feel compelled to espouse opinions in answers, we should label or attribute them.
And if we find them in answers in a way that causes offense, we as a community should be willing to edit them.
The following paragraph was edited out, rolled back (not by the author), and left to stand for three months, during which the author never joined the discussion. The issue was "resolved" as a side-effect: eventually its question was deleted:
All Biblical Perspectives (Judaism, Messianic Judaism, Catholic, Orthodox, Protestant) are reconciled in our one Lord and Savior Jesus Christ on the day of His Crucifixion. There is one Body, one Spirit, one Hope, one Lord, one Faith, one Baptism, and one God and Father of all.
This was an aside, not part of the answer to the question. The rejected edit also contained this change:
...on the day Jesus was crucified
and shed His Holy Precious Blood.
"That user is offended by everything" would be a good reason, but we haven't had anything remotely like that here.