A July 2022 renovation of the tag and others has changed the context of this question. It is now obsolete. Please see the following question and the link under "Conclusion." If we can't burn the "reality check" tag, can we rename it?
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I just read this question: Effects of a larger value for the Gravitational Constant?

It has both the and tags attached to it. So I went and read the summary and wiki for .

Though not my question, a legitimate question could be, why do we even have this tag?

However, moving forward with the idea that this tag should exist, then theoretically (at least from my point of view), it should be one of four mutually-exclusive tags:

  • Answers are allowed to dream wildly about solutions, but the solutions are NOT based in any way on magic. E.G. "How can I repair a broken bone?" answer: "nanites." (This tag would be as close as we're willing to go to "technobabble." Answers are expected to have some vague tie to science as we know it... but answers should be more than just "sounding" cool.)
  • Answers are allowed to diverge from known science, but they should have their basis in known science. E.G., "How can I repair a broken bone?" answer: "Using stem cells as your baseline tech, apply a fluid in a manner similar to applying a glue to the broken bones, then cast them together."
  • Answers are not allowed to diverge from known science at all — and respondents need to provide math and/or citations to prove it. E.G., "How can I repair a broken bone?" Answer: "with immobilization and proper nutrition."

And finally, one that is NOT part of the above sequence...

  • The OP is required to provide the rules of their world and a specific circumstance, situation, or question that is evaluated against those rules for consistency of use and scope. Answers are of the form YES or NO but are encouraged to provide insight for the OP's benefit.

At this time the tag is not formatted as part of the mutually-exclusive sequence. The linked question surprised me because, frankly, it seems nonsensical to ask for a evaluation to a fictional condition. But that might just be me.

Question: Is the tag part of the mutually-exclusive sequence as described above, or is it something entirely different?

The tag's summary and wiki should be updated either way. Please note that if you vote "entirely different," you're also saying that and can be used together, which makes even less sense to me for some reason.


3 Answers 3


I don't see why the two tags are mutually exclusive. We have plenty of examples of science-fiction works and worlds which have solid feet in hard-science (Verne's From the Earth to the Moon, just to name one), and also science-fiction works which are so loosely science based to the point of being almost magic based.

  • $\begingroup$ This point is certainly conceded, but what's the purpose of the science-fiction tag if they are not mutually exclusive? All questions not tagged magic are, by default, science-fiction. (See the highest-voted answer to Should we have the science-fiction tag?) $\endgroup$
    – JBH
    Commented Jul 28, 2021 at 17:52
  • $\begingroup$ @JBH Do you mean that we shouldn't explictly tell when something which is science-fictionny to be science-fictionny? Feels weird, it's a bit like you have a switch on an elevator with one side marked "move up" and the other... Nothing. It's oversimplified but I guess you get what I mean :) : It's not because they can be defined by their opposite that they shouldn't be told. $\endgroup$ Commented Jul 29, 2021 at 22:33
  • $\begingroup$ @Tortliena The default condition of this Stack could be described as science-fiction. If a question does not have any form of magic, nor the science-based, hard-science, nor reality-check tags, that's how we proceed-ish. The Stack today is much more science-based than it once was, so maybe the default is now science-based, but my point is, if no such tag is used... what do we expect? Frankly, if the science-fiction tag isn't mutually exclusive and used to represent the bottom-of-the-stack condition, what tag should? What would be the difference? $\endgroup$
    – JBH
    Commented Jul 30, 2021 at 2:10
  • $\begingroup$ @JBH You can create a world without science-fiction, you know. Medieval or simili-historical worlds without (or almost without) magic often can't really claim to be about science-fiction, look at things like the Game Of Thrones. In its broadest (like Clockwork Orange) or "spaceship pew-pew!" definition. Same with geography and nature which -alone- isn't a source of science-fiction nor magic. $\endgroup$ Commented Jul 30, 2021 at 5:03
  • $\begingroup$ @Tortliena Tags don't scope the questions. They scope the answers. They identify limits respondents need to meet the expectations of how Stack Exchange wants this Stack to be used. If you have further comment, please consider posting an answer. Thanks. $\endgroup$
    – JBH
    Commented Jul 30, 2021 at 5:06
  • 1
    $\begingroup$ @JBH I can't, it is actually off-topic to your question, so better as a discussion :). $\endgroup$ Commented Jul 30, 2021 at 11:27
  • $\begingroup$ so its ok to put both tag in same question? i remember reading some backlash in the past regarding a tag that contradict each other, like magic shouldnt be put along with hard science/science based etc $\endgroup$
    – Li Jun
    Commented Sep 3, 2021 at 9:00

The genre is known as "hard science fiction".

Hard science fiction doesn't have to consider economics or other resource limitations, it only requires you to be within the limitations of science as we currently understand it.

Generation ships are allowed, mining asteroids is allowed, extra-planetary bases are allowed. All these things fall within both and , none of them are politically or economically viable but they're all technically possible.

One could suggest that is redundant as it's a different meta set (including which certainly is exclusive to hard-science), but the two are certainly not exclusive.

  • $\begingroup$ hard-science has nothing to do with the genre "hard science fiction." In fact, since it mandates that answers must be supported through mathematics and/or citations, it's impossible to have both those tags on the same question (you can't expect proof for a fictional answer....). If you believe I'm in error, could you provide an example of a Q that could have an answer adhering to both tags? $\endgroup$
    – JBH
    Commented Aug 1, 2021 at 1:56
  • $\begingroup$ @JBH, it has everything to do with it, because it's the context under which the hard-science tag exists. This is a stack that's fundamentally about fiction, anything with a science tag could carry a science fiction tag. $\endgroup$
    – Separatrix
    Commented Aug 2, 2021 at 7:26
  • $\begingroup$ So am I asking the wrong question? Despite my belief that we're missing a valuable tag between magic and science-based, if we can assume all non-magic questions are fundamentally science-fiction, then it should be burned as worthless. What tag, then, should exist between magic and science-based? Or do you believe science-based allows for an entirely fictional answer so long as there's a scientific reference? $\endgroup$
    – JBH
    Commented Aug 2, 2021 at 8:00
  • $\begingroup$ @JBH, I think science fiction is entirely redundant in the grand scheme, the one between magic and science-based is reality-check for internal self-consistency and a touch of scientific basis. $\endgroup$
    – Separatrix
    Commented Aug 2, 2021 at 8:55
  • $\begingroup$ Reality check is a completely separate creature from the "science-*" series. In fact, it has nothing at all to do with science or magic. Present your rules and a scenario or issue to compare them against, and we'll tell you if its consistent. That's it. $\endgroup$
    – JBH
    Commented Aug 2, 2021 at 15:23
  • $\begingroup$ @JBH, it's always been one of the set of three, regularly discussed over the years. Reality-check, science-based, hard-science as a sliding scale of how seriously to take the scientific aspects. It used to be in the tag descriptions, though that seems to have changed. $\endgroup$
    – Separatrix
    Commented Aug 2, 2021 at 16:20

IMHO worth a paltry 3k rep. The Hard science tag should be replaced and redefined or discarded. The world at large, when they come across the tag sees Clarke, Niven, Weir, Anderson. They don't see Einstein, Curie, Hawking, Bohr. While Ringworld and Rama, have reams worth of science and equations to back them up. they are still impossible and wouldn't stand up rigorously to a Hard-Science tag. Skrith and reactionless drives are both handwavium. I know the Definition of Hard-Science, I also know to 90% of people that would consider building a world, the real definition is secondary, the first thing that comes to mind with its utterance is something completely different.

Vanishingly few posts that include the tag at creation, ever keep it. Many are closed are abandoned from the hassle.

I realize that WB is one of the more unique/odd among the stacks and apparently it's existence within SE is questionable for the content that it deals with. We have to do our best to stay within the guidelines, and keep the metaphorical "genie in the bottle". However, since nearly every relevant question ever asked on the stack, asks for an opinion based answer. Reality-Check: We think we have the answers, but we cant even truly answer why light looks fuzzy around the edges when it passes through a couple of slits.

A "Hard-Science" like tag has a place I think, but under a different name. It's confusing for new-comers, fresh breath and blood to the stack. Every effort should be made to make them feel welcome and unafraid to ask. We here know that a VTC is just a necessity and only procedure. To the new, it's a rejection, a demerit. Especially the social media jungle, any slight is exaggerated.

  • $\begingroup$ This should probably be a separate post, proposing the removal of the tag rather than an answer to a question about whether tags are mutually exclusive. $\endgroup$
    – sphennings
    Commented Aug 1, 2022 at 19:37
  • $\begingroup$ You may not of noticed, but this post was marked Obsolete two weeks ago due to the update made to the science-fiction, science-based, hard-science, reality-check (which doesn't exist anymore), and internal-consistency tags. Why are you answering an obsolete post? $\endgroup$
    – JBH
    Commented Aug 1, 2022 at 19:37
  • $\begingroup$ And for the record, the only reason it's confusing to new comers is they seem to have trouble reading the tag summary (much less the wiki). So it appears what you're basically saying is, "new users are ignorant and we should accommodate that." I hope you can forgive my peevishness, but some breathtaking questions and answers have come from the hard-science tag. And now that we finally have a consistent sweep of intent through those tags, someone wants to change them because, apparently, they're too hard to use. $\endgroup$
    – JBH
    Commented Aug 1, 2022 at 19:43
  • $\begingroup$ @JBH You appeal to my sense of absurdity. Yes, Im saying they are ignorant, New by definition implies ignorant. Instead of using a tag more whose meaning is more easy transmitted, you accommodate the new user by using a word which meaning in the community is far more entrenched than the SE definition. Add functionality into the site to emblazon the post specifically for this tag after it's been posted with the warning "This question asks for hard science. " that user can't get rid of themselves. When it was all a predictable misunderstanding to begin with. Just because it's too hard to adapt $\endgroup$
    – Gillgamesh
    Commented Aug 1, 2022 at 20:15
  • $\begingroup$ In most instances we, the community, catch the issue, remind the user, and correct the tag before the Moderators get involved. $\endgroup$
    – JBH
    Commented Aug 1, 2022 at 20:44

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