Question: The [Good Subjective/Bad Subjective guidelines](http://blog.stackoverflow.com/2010/09/good-subjective-bad-subjective/) talk a lot about what make for great questions and answers for subjective issues, and it primarily falls around Back It Up!: answers need to cite some kind of relevant material (scholarly works, authoritative discussions, relevant personal experience, something), and questions need to be written such that they encourage such answers.

And, of course, Back It Up! applies to objective questions and answers, too, the resources you use for backing those up just may be somewhat different.

So, we need to be pro-active, from the beginning, about demanding that answers Back It Up! This SE, in particular, I think, is closely tied to a lot of speculative fields – as several meta questions have already discussed, there are a number of SE sites that have significant overlap with this one, *but would not accept our kind of question* because of their speculative nature.

Thus, we need a policy, guideline, or at least discussion of what is too speculative, what questions cannot be answered in a way that Backs It Up! The “Primarily Opinion-Based” close reason exists for this, but we as a community have to decide where to draw the line for using it.

We also, as a community, need to enforce backing things up in answers. Everything about this endeavor is, by definition, highly speculative: the only way to be serious about this, to produce good answers, is to minimize, as much as possible, the “pure” speculation. Cite sources, compare to real-world history, sociology, physics, and so on. And flag or downvote answers that don’t.

Answer: 
**This site is a site for asking speculative questions**  

If there was hard fact to back up a physics question, it would be on Physics.SE. If there was hard evidence on what benefits a Timelord's two hearts gave him, then it would be on Biology.SE. 

**That said...**  

If you have work that you draw upon or facts that you used to help make an estimate, please share your sources. I am always happy to see a question filled with links to aid in speculation and cause and effect, however I do not believe that this should not be a barrier to someone who has an insight or understanding that they can contribute.

Frankly, I believe that insisting upon sources for speculation and imagination will not only be detrimental to this site, but would *probably kill it*.

Sources:

* Gut feeling
After some brainstorming on chat I think that there are three kinds of questions, that should have different Back It Up policies for answers:

1. **Hard Science questions:** answers should be properly backed up with documentation or scientific articles, and could potentially be posted on specific scientific-subject sites such as perhaps Astronomy, Biology, Chemistry, etc.
2. **Fantastic science** or **pseudoscience:** answers should be backed up by solid reasoning in the way of (citing @MichaelKjörling) "if we were to assume that Thing X exists and works as hypothesized, then it would be possible to use it to perform Miracle Y by doing A, B and C." This form could be used to explain, for example, how a hypothesized type of particle could be used to perform something which cannot presently be done
3. **Pure fantasy:** answers should be reasonable, and can be based on personal experience, readings or whatever other means.

**All** answers must be internally consistent, as well as in line with the asker's specified requirements, whether those are "hard science only" or "magic fairy dust exists that works like this: ...".