Good Subjective, Bad Subjective refers to the Back It Up principle that was developed on an early SE site. I've seen this principle in use on UX (though I can't find an example right now), and citing sources or experience is standard on Mi Yodeya.

Backing up an answer includes citing sources, making a logical argument, and sharing relevant personal experience. The idea is to show your work rather than to simply assert something as true.

How widespread is the Back It Up principle on other sites where "compile it and see if it works" doesn't apply? Can answerers, err, please back up answers with links to these policies where they exist?

Edit: While I appreciate (and have upvoted) the answers received so far, I am still hoping for a comprehensive list. I understand from the answers and comments that Gaming, Skeptics, SF, and Workplace have forms this policy; who else, and what shape does it take for each? Ideally one answer would list and link as many of them as possible.

  • On gaming it's generally encouraged, especially for anything that can't be very easily and immediately verified in game (say, "it's in settings" is fine with no reference, but "don't kill that guy or you can't get the good end" might need more backup)
    – Zelda
    Commented Feb 12, 2013 at 15:18

5 Answers 5


This list was initially compiled from other answers and comments. I'm making it community wiki; please update so we can have one comprehensive list. Please add links to the places where these expectations are spelled out.

The following sites have some form of a back-it-up guideline/policy/rule:

The following sites don't have this as an official rule but operate in a way that strongly encourages the practice:

  • 3
    Politics do not have a Back it up policy... though I really wish it would adopt one or if it does exist then enforce it, though I think it could go in the strongly encouraged section.
    – Chad
    Commented Sep 23, 2014 at 20:11
  • Law strongly favors citations to actual laws, court decisions, law review articles, and other reliable sources to back up statements, and when a statement is challenged expects such citations to be provided. Commented May 27, 2021 at 14:58

Some sites would do better with a variation of this principle that is not always supported by the post notices sometimes used by moderators enforcing the back-it-up approach. Travel comes immediately to mind. If you ask about lineups at a particular attraction, the likelihood that a cabbie will be able to give you change from a large bill, or the cleanliness of a particular hotel, which answer would you prefer?

I was there last week and [anecdote]


According to Wikipedia [link], [statistical fact which may be out of date, or official position which does not reflect reality on the ground]

One answer on Travel once got one of those "please cite sources" banners:

This post does not cite any references or sources. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed

I flagged asking to have it removed, which it was. Great idea for some sites, but remember we do have some where recent personal experience (for some questions anyway) is actually better than a published, verfied, and possibly out of date or unrealistic "fact".

I'm not saying the plural of anecdote is data. I am saying for some sites, anecdotes are the one thing we can't find from a web search and they are more valuable than data. So if we are to have a system-wide "back it up" principle, and if moderators are likely to use this post-notice on answers that aren't backing it up, we need to either have different post notices (one like the above, and one more pesonal-experience-friendly) for different sites, or two post notices and the moderators choose the right one for the site.

  • 11
    As I understand it, "Back it up" includes personal experience, cited as such, as a worthwhile source. What's the principle comes to exclude is theorizing or asserting without even a claim of basis in fact, e.g. "I don't think anyone's really going to like that attraction." or "Cabbies don't carry any change." without support. Commented Feb 12, 2013 at 19:18
  • Isaac's understanding is the smae as mine. I've clarified the question. Commented Feb 12, 2013 at 19:51
  • 4
    the banner that can be added (the one I flagged on Travel) specifically asks for "adding references" and "citing sources". If we're going to have a sitewide banner we need to be sure that it is personal-experience-friendly Commented Feb 12, 2013 at 20:00
  • 1
    Aha! Your quarrel is with the use of part of the post notice feature, which allows a mod to append a prefab notice from a menu to an answer. One of the choices is This post does not cite any references or sources. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed., (e.g.) which I agree with you makes less sense on most of SE than it does on WP or Skeptics.SE. It should be reworded or not used. ... Commented Feb 12, 2013 at 21:13
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    ... Much better is a different existing option: (e.g.) We're looking for long answers that provide some explanation and context. Don't just give a one-line answer: please explain why you're recommending it as a solution. Answers that don't explain anything will be deleted. See Good Subjective, Bad Subjective for more information. Commented Feb 12, 2013 at 21:13
  • 3
    Yeah, just to be clear, I'm not asking about the post notice (which I hadn't noticed until this answer pointed it out) but about the policies that sites on the network use. Commented Feb 12, 2013 at 22:21
  • 2
    @MonicaCellio I've edited my answer to reflect that I agree with "back it up" everywhere (as long as personal experience counts as backing it up) and that a general adoption of Back it Up would require some edits to the post notice. Commented Feb 12, 2013 at 22:27
  • Great phrase, "the plural of anecdote is data", which you ascribe to other people. Upvote for that reason. Commented Aug 18, 2016 at 11:46

It varies from site to site. The most strict site is probably Skeptics, which requires a citation for almost every statement or claim that is not common knowledge. But it applies to a greater or lesser degree on almost every site. Even Science Fiction and Fantasy encourages references.


We have a "back it up" rule on The Workplace. From the site's FAQ:

How should I answer?

Make sure your answer adds helpful information and is a complete, stand-alone answer. Read other answers first and be sure not to completely restate information that has already been posted.

Please note that answers should be backed up either with a reference, or experiences that happened to you personally. You should always include in your answer information about why you think your answer is correct.

Speaking as a relatively high rep user on the site, the rule has been reasonably successful. Relevant Meta discussions:

There's an on-going Meta discussion on Politics to create a similar policy.


On Board and Card Games, it's not an official policy, but it is strongly encouraged (by the way people vote) for all questions, but particularly for rules questions. I'd sum it up as "the community prefers hard evidence, where available, but will settle for logical analysis otherwise". Opinion answers are acceptable, but they are definitely rarer.

As a mod, I do leave gentle comments encouraging evidence when people provide rulings without backup. Quoting the relevant portion of the rules (and linking to them, if available online) seems to me to be the minimal acceptable work here, if you want someone to trust your answer.

The 'show your work' concept seems like a no-brainer to me. Why should anyone value your answer if you can't provide any justification for its existence?

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