For some time now, I have told folks on Stack Exchange that book recommendation questions are off-topic throughout the Stack Exchange network, citing this blog post.

Book recommendation questions are aggressively closed on Stack Overflow and Programmers (much to the consternation of some community members). As Shog9 puts it, we don't want to duplicate Amazon reviews, badly.

However, it seems that on some sites such as Physics, book recommendation questions are not only allowed, but actually encouraged.

Are individual communities allowed to decide whether such questions are on-topic for their site? What is the criteria for determining whether such questions will stay constructive?

See Also
The Definitive C++ Book Guide and List
What Books Should Everyone Read?
Book questions on Mathematics.SE

  • Just curious, but what/who did actually decide that book questions are not appropriate for SO/Programmers? Was this ultimately something the community arrived at or somehow decided/enforced? (fwiw, I do agree with it being off-topic)
    – Bart
    Commented Nov 26, 2012 at 23:37
  • 2
    Related: Individual community preferences vs. SE network policy: who wins?
    – yannis
    Commented Nov 26, 2012 at 23:38
  • 3
    @Bart For Programmers, see: Are book recommendations on-topic?
    – yannis
    Commented Nov 26, 2012 at 23:39
  • My guess is that the statistics play a role - i.e - for Physics, most people asking about books are pretty serious. But on SO-proper, it's these newbies sayin "GIMME BOOK" Commented Nov 27, 2012 at 0:10
  • 1
    @Adel: There is some merit to that. The mother of all book recommendation questions is kept open, because the curators of that question actively maintain it.
    – user102937
    Commented Nov 27, 2012 at 0:13
  • On Physics, we allow(ed) book recommendation questions only for textbooks in the major fields of physics. Answering these questions is not just a matter of "pick your favorite book;" there is a more-or-less standard set of textbooks which are widely acknowledged as "preferred" references throughout the physics community, so there is a standard set of answers to give. Our book recommendation questions are not as open-ended as book recommendations on a site like SO or Programmers.
    – David Z
    Commented Nov 28, 2012 at 3:38
  • Plus, the book recommendation questions are actively curated (well, for now... by me). We only allow those which fit the pattern described in one of the posts you linked to, and increasingly, most of them have been asked. These days probably 90-95% of all book recommendation questions asked on Physics are closed. So I wouldn't say they're encouraged. Certainly they're not encouraged or allowed in general, only some specific ones are.
    – David Z
    Commented Nov 28, 2012 at 3:40
  • I'll add that the book recommendation decision on physics wasn't unanimous, but @DavidZaslavsky and mbq and most of the user seem to want it, so we've got it. So far the results have not been bad, aside from needing a steady hand for identifying duplicates. Commented Nov 28, 2012 at 16:18
  • It is exclusively the business of the individual communities!
    – Dilaton
    Commented Aug 9, 2014 at 21:38
  • @Dilaton: Post an answer, with some justifications.
    – user102937
    Commented Aug 9, 2014 at 21:44

2 Answers 2


Individual Communities Do Have a Say

From my experience, to a large extent, individual communities do have a very strong say in what is accepted on their site. For sites that have been in beta for awhile, it seems that the community team rarely, if ever, gets involved, unless something becomes a significant problem or if the site starts to show signs of growth, combined with a pattern that, from experience, will lead to chaos. It's when the issues are noticeably harmful that they'll step in.

Thus, if a site accepts book recommendation questions, and these happen very infrequently, and those questions tend to actually get answers based on facts, references, specific expertise, or that are backed by personal experiences, then Stack Exchange is not likely to get involved. If you think about it, this makes sense. If the community isn't harmed by such questions, why dictate a policy that doesn't fit.

As a pro temp moderator on Project Management SE now for almost 2 years, I've found there are many things that our community hasn't yet come to a consensus on. As a moderator, I try to stay out of moderating certain areas where there isn't at least some consensus or community support, and in my experience, putting these decisions on hold haven't caused our site to implode on itself.

As we have grown over the last 21 months, we have improved our FAQ and have explicitly marked tool recommendation and book recommendation questions as off-topic, mostly because they attract a lot of spam and low quality answers. This isn't something that happened overnight; instead, we made this decision after the community experienced first-hand how it looks to have questions like these litter the main page.

But still, if one of these questions shows up on our site, we still evaluate it based on its own merits...

Lighter Moderation

If you look at A Theory of Moderation, it's clear the leadership of Stack Exchange prefers pro temp moderators to take a lighter approach to moderation, instead of a heavy handed approach:

Even with active community self-regulation, moderators occasionally need to intervene. Moderators are human exception handlers, there to deal with those (hopefully rare) exceptional conditions that should not normally happen, but when they do, they can bring your entire community to a screaming halt — if you don’t have human exception handling in place.

With 5,000 questions per day, it's critical that the standards of Stack Overflow be strict and well-defined. Now, why is this? I'll venture to say it's because you can't reason with millions of people who may detect a pattern and follow suit. However, on a fledgling beta site with 2 questions per day and people you almost know by first name, it's much easier to guide the community and take more time in determining if something is harmful or beneficial. If it's not going to bring the community to a "screaming halt", then perhaps it's best to not act but instead to start a meta discussion.


I don't have the link (so maybe it didn't happen), but Jeff and Joel said once that, being programmers, it was easier to start Stack Overflow and moderate it themselves. But for Q&A sites about topics they had no experience in, they didn't feel they should dictate all of the rules.

What this basically comes down to is leadership. Each community must become self-governing, and to make this happen, Stack Exchange must to some extent get out of the way and let community members work out their own problems. At first, there may be a lot of mistakes, but part of being a leader is letting people, communities, and moderators make those mistakes, and then offering assistance and guidance when problems arise that the communities cannot handle themselves.

Of course, it's also possible that we discover that a policy made for one group of Stack Exchange sites is unnecessary for another. This find wouldn't occur if hard-fast rules were strictly enforced from day one.

How to keep these questions constructive:

1. Make sure the question is about a real, actual problem and not just a poll for books.

If someone asks a question about a book, hopefully they've also described a problem. On PMSE, many of our tool recommendation and book recommendation questions accompany a problem the OP is facing; thus, the community responds with solutions first. Many of these questions are answered without even mentioning a book or a tool. The best questions are about a real, actual problem you're facing, and even a book recommendation question can contain these elements.

If the question is simply a poll asking for books or tools, with no problem description, we happily close these.

2. Answer the questions by clearly providing a solution.

Don't just answer with a link or the name of a book. Explain why it can help solve the problem, but also be sure to share your own expertise and answer the deeper question. When someone asks for a book, what they really want is an answer to some other problem, so give them an answer that might even make it so that they don't need to go buy the book. After all, that's what Stack Exchange is here for. ;)

Again, this depends on the asker actually describing the problem. In general, asking in the comment, "What are you hoping the book will help you with? Can you describe the problem you're facing?" can help draw this out of the asker.

3. This depends on the community

If the community's response to these types of questions is largely link only answers, with no attempt to solicit more information from the asker via comments or attempts to improve the question, then these questions just simply may not work for that community. If people rush to answer without meeting the first two guidelines, providing only superficial answers, then the community may want to consider disallowing these types of questions.

If the community does a good job cleaning these posts up via editing, commenting, and providing superior answers, then the cost of disallowing these questions may only serve to alienate people for no good reason. Whether or not these questions can exist depends on whether or not there are enough users who can lead by example, and if disallowing the questions is going to be more harmful to the community than allowing them, then maybe it's a good idea to simply keep a watchful eye on them and only bring up the issue in meta if it becomes a problem.


The very first comment on the Q&A is Hard, Let's Go Shopping! blog entry asks how that policy would affect book recommendations, and the answer begins "I’m not entirely sure it’s related" and goes on to ask for more context.

Also, on Programmers it has never been decided that all book recommendation questions should be closed. In practice, they have little chance of surviving since it attracts close votes, but there is no blanket policy to close all of them. And for a while "canonical" book questions were allowed, until it was quite reasonably pointed out that it puts the moderators evaluating close flags in the impossible position of determining whether any particular programming book in the universe is really canonical.

The normal guidelines for a questions still apply, and work well, for book recommendation questions. If it is a poll question then it isn't constructive, if it's too localized it isn't acceptable ... yada yada yada.

I think the differences between sites makes sense given the topics they cover. Technical books tend to have a very short half-life, many dimensions they can be evaluated on, and a fair number of holy wars. So, even though in principle book recommendation questions can be acceptable, it is hard to solicit good answers and some communities have enough bad real-world experience that they treat book recommendation questions with a great deal of skepticism.

So, I think there don't need to be any special guidelines for book recommendation questions, and that they aren't off topic or non constructive as a class, even if many specific book recommendation questions are. I don't think there is any reason to consider them off topic network wide, nor should they be, since there are examples of dealing with them very successfully. However, I don't see why a site couldn't decide they were off topic for that site.

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