# How to answer when the question is based on a wrong premise?

I ask this wondering about my answer to this recent question, though this applies in a more general setting. The situation is that the question asks about the physical interpretation of the typical curved-spacetime-as-rubber-sheet analogy, which as has been said multiple times on the parent site, is not a good analogy and should not be taken literally.

In my opinion the question as it stands is not answerable; the only answer I can imagine (and the answer I gave) is that essentially the question is wrong, along with explaining why. However, some people thought that should be a comment instead. I can think of three possibilities:

1. Answer the question as best I can, even if the answer technically does not answer the question.

2. Close the question. I do not agree with this because AFAIK having wrong premises is not a close reason; I believe such questions are valuable since they address common misconceptions.

3. Simply leave a comment instead of an answer, as some people suggested. I don't agree with this either, since it seems strange that a question should remain open and yet undeserving of an answer.

Which option is best? (Obviously I support #1.) Is there another alternative? In some cases one could answer a related question that does make sense, but in this particular case that would essentially amount to explaining the basics of GR, clearly too broad for an answer.

• Or option #4: state the question is ill-posed, but offer an answer based in a reasonable interpretation that the question is asking about the gradient of the metric or the geodesic or something else related. – Kyle Kanos Jun 21 '18 at 22:21
• Note also that you chose to point out a flaw in OP's statement(s), which isn't an answer to the question but a comment. We have comments expressly for the reason to pointing out flaws in statements in hopes to clarify the question. – Kyle Kanos Jun 21 '18 at 22:25
• @Kyle I understand your arguments, though I asked this question hoping to address the general case. Imagine for the sake of the question that any reinterpretation of the question would just be too far-fetched. (I can't really imagine what I could add to my answer without turning it into a textbook, and so far no one has offered an alternative.) – Javier Jun 21 '18 at 22:29
• I don't think you do understand the arguments, otherwise you'd have deleted your answer and posted it as a comment. – Kyle Kanos Jun 21 '18 at 22:32
• @Kyle I can understand the arguments and not agree with them. So far no one has offered a (to me) satisfactory alternative, though you're welcome to flag my answer to be converted into a comment. – Javier Jun 21 '18 at 22:34
• there's nothing really to disagree with though. You posted something that points out a flaw in the question, ergo it is a comment and not an answer. What is difficult about that? And I've given you two reasonable interpretations you could add, but you reject this for some ridiculous reason. – Kyle Kanos Jun 21 '18 at 22:39
• Put it equivalently, if someone asked, "What is $v+a$?" (For vel & accel) your answer would essentially be "You can't do that." That isn't an answer to the question and isn't particularly helpful to anyone. – Kyle Kanos Jun 21 '18 at 22:45
• @KyleKanos Maybe I'm nit-picking or misinterpreting things, but in the example you gave, isn't it useful enough to say "You can't do $v$ + $a$ because the units are different and they represent different things, hence they're rendered meaningless by attempts to add"? I would think that's an acceptable answer, because it tells you implicitly yet clearly that $v$ + $a$ is meaningless. – user191954 Jun 22 '18 at 10:28
• (continued) Applying this theory more generally, I think it may be appropriate to simply state that the premise is wrong, the reason why it's wrong, and the implications of the mistake upon the deduction made (explain that if $v$ and $a$ are different physical quantities with different units, their sum isn't defined). – user191954 Jun 22 '18 at 10:35
• @Chair if you added that, maybe, but I don't think that's what Javier had done here. But there is a reasonable interpretation where OP has a unit of time ($t=1$) and so it's $v+at$ and they (hastily) posted an incomplete query. – Kyle Kanos Jun 22 '18 at 10:56
• And yes, that has happened before on this site. – Kyle Kanos Jun 22 '18 at 10:56
• Kyle, it doesn't matter what Javier did. The question he has posted here is legit on it's own merit and independent of that. Regarding the hypothetical question, I think Chair's view is correct that an answer like the units are different would be useful. I find your original claim that such an answer "isn't particularly helpful to anyone" absurd. To wit, it would probably useful to anyone else asking the same flawed question. That you say this has happened before proves the point. – Jason Arthur Taylor Jun 24 '18 at 21:01
• Moreover, flaws in questions are more common that you probably think. Answers addressing just those flaws, especially the most common ones, likes the ones I discussed in my own answer to Javier's question, are valuable. Askers should not be expected to fully know the field they are asking about. It is not realistic, and would stifle both learning and scientific progress at large. – Jason Arthur Taylor Jun 24 '18 at 21:11
• Flawed questions have become extremely more common at physics.SE. I'm sadly starting to think that this site may have run its useful course as a Q&A site, much as has the granddaddy site, stackoverflow.com. Strictly IMHO, of course. That said, my contribution to stackoverflow peaked years ago, and I'm far from alone in that regard. I started noticing that questions at stackoverflow.com from low to middling ranked members were becoming of increasingly low quality, eventually becoming so low quality that I don't even bother. I'm starting to see the exact same phenomenon occurring at physics.SE. – David Hammen Jul 5 '18 at 6:11

It rarely does any harm to answer a question, and you never know who else might stumble across your answer and find it interesting. There have been cases where I've written an answer to an essentially meaningless question because (a) I thought there was some interesting physics to talk about and (b) I enjoyed writing the answer - option (b) is often my main motivation :-)

So if you're going to find it gratifying to write an answer then do it and damn the torpedoes.

There is an argument that writing answers to careless and/or lazy questions just encourages them and makes the site a worse place (this is why we discourage answers to homework questions). Whether this applies to the question you plan to answer is a judgement call.

• I upvoted your answer, but I wanted to point out something I disagree with that you wrote. The criterion that an answerer finds it gratifying to post an answer should not in and of itself be a rationale for allowing it. A better criterion is, "Will the answer be of enough value to others in the future?" Ideally, those will match up. However, there are probably people out there who post on, $e.g$., blogs, as a way of, $e.g.$, coping with personal issues they are having. Posts like that might be counterexample to what you wrote in your answer. – Jason Arthur Taylor Jun 24 '18 at 22:15

As usual, it depends. Consider the following two extreme cases:

• The premise is so wrong it is not even wrong. In this case, the only thing we can do is to vote to close as unclear; and, ideally, to leave a comment explaining why the premise is wrong. Nobody but OP will find the question useful; and most of the times, speaking from experience, not even OP will. The initial question is meaningless, so it is not answerable, and if you fix it, you'd be answering a question nobody asked.

• The error in the premise is minor. In this case, the error either invalidates the question, or it doesn't. In the first case, correcting the premise constitutes an answer by itself; in the second case, the error should be fixed, but its presence is tangential to the main question. In either case, the question is answerable and useful to other people. Especially when the error in the premise is subtle and you could see more people falling into it.

Of course, things are not in general black-and-white. It is not always easy to decide whether the question should be closed or answered. This is one of those cases where reasonable people will sometimes disagree, and there is no general solution to that. Good thing we have a voting system!

• To make things a bit clearer, could you give an example of what's 'so wrong that it isn't even wrong'? I was thinking it may be pretty much anything that isn't an ordinary misconception, but it would help if you could provide an example to make things a little bit more definite, even though you did mention that it's a grey area which depends a lot upon the perspective of the reader... – user191954 Jun 22 '18 at 10:39
• @Chair It's hard to find examples of bad questions, because those usually get closed and deleted. I could find many examples of questions with minor errors (I could even give you one of my last few questions as an example), but questions with big errors, not quite so. The "lowest voted - last 30 days" list is useful because recent bad questions have not been deleted yet; the worst one is physics.stackexchange.com/q/412320, which I guess is a fine example of "not even wrong" question. – AccidentalFourierTransform Jun 22 '18 at 13:08
• Sure... so where in the spectrum would you place this? I think the answer handled it quite acceptably, by saying 'let's treat it as a thought experiment..." But the premise of the question is as wrong as they get, in my opinion. – user191954 Jun 23 '18 at 11:31
• @Chair I would put it very close to the "not even wrong" extreme. Asking what would happen if the laws of physics were broken is not something physics can answer in general. If you choose to invalidate some part of the framework, the same becomes inconsistent, and you cannot really use it to predict anything else. The question could be on-topic on worldbuilding, though. – AccidentalFourierTransform Jun 23 '18 at 13:32
• I support this answer with the qualification that the bar for being "so wrong it is not even wrong" should be very high. In other words, in order for a question to meet the criteria of the first bullet point (in my view), the premise has to be absolutely nonsensical, outlandish, grossly misinformed, etc. That case is relatively rare. The question that @Chair linked a couple comments up does not meet that bar at all IMO, so I would put it in the second category. (Though it is probably a duplicate of something.) – David Z Jun 23 '18 at 23:57
• @DavidZ AFT emphasized that it's a grey area, so everyone'll place the standards differently, even when all are trying to decide whether or not the question is "outlandish and grossly misinformed". This makes things tricky. You think there's a way to define the question's incorrectness based on the knowledge of the author? For example, I thought the question I linked earlier was terrible because the OP knew that a massive object can't cross the speed of light, yet he asks what happens if one does. It's obvious that physics doesn't explain what happens when the laws of physics are broken. – user191954 Jun 24 '18 at 5:08
• I'd go even further than David Z's desire about needing a very high bar. I think it should be limited only to prevent spam. Questions with serious issues can be answered by something like, you might want to review this website, which discusses some of the basics about this topic, such as x and y. A reason I think that is useful is because research is about exploring what we don't know. If we close "bad" questions we stifle creativity. Also, as I suggest in my own answer, teachers can be wrong. Yes, some questions are irritating. But, they help can illuminate ignored issues in science. – Jason Arthur Taylor Jun 24 '18 at 21:47
• In my experience questions with "not even wrong" assumptions are often closed as "non-mainstream." I don't really agree with this if the questions are asked in good faith, but it's what often happens in practice. That might be a good way to find examples, if there is a way to search by close reason. (But I cannot work out how to do that.) – Nathaniel Jun 26 '18 at 0:47

The best approach is indeed to submit an answer that pays special and enhanced focus to the alleged error.

As a preliminary comment, I think that this question is probably a general stack exchange meta question, not a question specific to physics.meta.stackexchange.com.

As a second preliminary comment, I think option #1 needs to be split up. Option #1 says, "Answer the question as best I can, even if the answer technically does not answer the question." A problem here is "as best you can." In most cases, I think a reader would take this to mean, fix the implied errors, and just answer the intended question. Indeed, in this answer I will end up giving two examples where this occurred. But, as you've pointed out in your comment, what you actually meant is to avoid "fixing" the question (the opposite), and to focus on the issue(s) with the question instead. In this answer, I will call your intended option #1, option #1, and the fixing option, option #4.

To be extra clear, these definitions mean that only option #1 is able to encompass the contentious situation that I encountered yesterday and which the asker, Javier, also apparently encountered in which an answerer submits an answer that intentionally refuses to try to answer a potentially intended (i.e., fixed) question. However, option #1 is not restricted to this, either. My option #4 here is the least antagonistic option possible, for it glosses over potential issues and makes the asker look the most intelligent; all the other options #1-#3 are all largely critical of the question itself.

For reasons I will soon give, I think option #1 is the correct answer. #2 (closure) is just censorship and it fails to help the poster with their real roadblocks in knowledge. It is worth noting that closure, originally thought of as a great idea for these sites, was arguably the main thing the founder reversed when he left to to found Discourse. The raw point system is, itself, already a strong mechanism to prevent worthless clutter. #3 (a short comment) is horrible because it suggests that the alleged issues are trivial when they rarely are. I think #4 is the probably the most common route taken on stackexchage, and I will attempt to show why it is a bad option.

To help think about which approach is best, let us consider the ideal, perfect, learning situation. Then, let's pretend a writer here wants to get as close as possible to this idealized learning situation. Then, let's consider how to handle a bad question. Usually, these are questions which assume something that a potential answerer disagrees with.

I think it would be hard to dispute that a close-to-ideal learning situation is a tutee learning with a tutor who is knowledgeable in the subject being taught. One reason is that it is generally thought that a low student-to-teacher ratio is good, and this has about the lowest ratio that is still realistic. The question at hand, therefore, can probably be narrowed to, "How should an ideal tutor handle a tutee asking an allegedly wrong question?"

Without any doubt, in this situation the ideal tutor would not just internally correct the question and continue onward. Rather, the ideal tutor would put a spotlight on the implied alleged error of the question.

One reason is that knowledge of a subject, especially one like physics, is like a pyramid. In this analogy, learning is like building this pyramid of knowledge in a tutee's mind. A good tutor will try to make a good, strong, pyramid as efficiently as possible. The middle and upper layers of the knowledge pyramid require a good foundation of math, simpler physics, etc. Only once a solid foundation is in place should a tutor move the tutee up to the next brick level:

If, in building an upper layer, an allegedly bad brick is discovered, then all attention should be directed just to the allegedly bad brick below. Otherwise, the tutee will not have an ability to self-re-derive the layer the tutor is working on correctly. They might be able to memorize solutions to specific cases, but they will fail as soon as they are faced with an altered scenario, because this is when they will need support from that allegedly bad brick. The upper layer being built will be made of weak material, and tainted by potentially false knowledge. It will probably just fall apart in the student's mind after an arrogant tutor tricks oneself into thinking they've successfully built the upper layer and can now go even higher.

In my analogy, what such an arrogant tutor (or physicist for that matter) would really be doing is building a jenga tower:

The entire structure of knowledge will just crumble and fall apart as the student, once faced with, for example, a test question they didn't exactly see before, realizes they don't actually understand much of anything about the subject, and that, for example, they are going to get an F on the exam they are taking. The worst time for them to discover they have no real idea what is going on is during an exam!

There are a few approaches to fixing an allegedly bad brick revealed by an allegedly bad question. If it were me, I would probably say, "Wait a second. Let's back up a little. Your question was $x$. Are there any interesting assumptions you are making here? ... Can you show me how we got this?"

Perhaps you can see where I am going. I would want the student to eventually discover own their own that there is an error in their question. Alternatively, there is the possiblity that I'm wrong, in which case I will discover that I am the one making the error.

Of course, a good tutor might instead just directly point out the alleged error. Each approach will focus on the allegedly weak brick.

To continue the spotlight on the issue, I'd have the student do some problems about that "bad" brick that prove and demonstrate that the deficit in the question was fully and completely resolved. Only then would I allow the question originally asked to be addressed.

Importantly, there is the real possibility that the allegedly bad implied assumption is actually correct. (This is why I am, arguably irritatingly, insisting on injecting the "weasel word" allegedly throughout my answer.) Here we can really see why #2, #3, and #4 are horrible answers. By not directing the spotlight to the correct areas, potentially wrong assumptions can then persist in the ecosystem of potentially true and potentially false knowledge.

A good example to illustrate my position are the questions and answers here concerning understanding resistance and Ohm's Law. The situation with Ohm's Law is that a lot of engineers need to use this law. However, to derive it from first principles, getting the correct conductivity coefficients from basic things like atomic properties, could be rather complicated. I don't think it really requires quantum molecular dynamic simulations of finite temperature density functional theory, but this is the implication I gave here in response to someone claiming the law is impossible to derive theoretically.

Obviously, this would be over the head of your typical electrical engineer, so my guess is that a lot of textbooks resort to the Drude model in attempting to explain Ohm's law in which the electrons and atoms are treated like a bunch of billiard balls. The alleged benefit might be that this is easier to teach and give problems on. Within metals, due to the effects of quantum mechanics and the relatively low energies of the electrons, in my opinion the electrons should not generally be treated in this fashion. That is to say, some of the educational models being used are, essentially, not even worthless, but of negative value, getting in the way of real progress.

Perhaps you can see where I am going with this. If not, I think what is happening is that teachers are teaching bad models. This perhaps results in their students having a lot of questions. Their questions often have implied alleged errors in them, because the students are genuinely and rightfully confused. I think that the real problem is probably that the teachers are not teaching physics accurately. This trickles down into confusion in the students, who come here, hoping to resolve their problem. Some of the poorly instructed students end up here, thus exacerbating the situation.

I am arguing that the worst thing possible is that the accepted answers pertaining to issues with the Drude model are glossed over here (the #4 approach). Stackexchange then just worsens the underlying problems here, arrogantly suggesting the issues a student is having is their fault instead of the teacher's. It would foster people thinking they know what is going on when they really don't, perpetuating bogus physics and disinformation, stifling creativity and progress. That is not ideal for stackexchange.

Consider the currently-accepted answer to "Can someone in a simple way explain [to] me what the Fermi level is and what [it has] to do with conductivity[?] My teacher said that Cu conducts electric current better than Al because of something in relation to [the] Fermi level[.] I didn't get him very well, so please explain [to] me what it is all about, but in a simple way." I think that the currently-accepted answer has serious problems, largely because what is probably the best answer, involving Kubo's formalism, is complex and not that simple.

This example underscores the dangers of glossing over issues in questions. Doing that allows people to think they understand how something like conductivity works, when they probably don't.

This is not some bizarre example, either. Can you estimate the fraction of physics papers that convert into Nobel prizes? A hint is that there is only one prize award per year, but the number of papers published each year is growing rapidly. Most papers are loaded with what history will prove to be bad, implied, and ignored assumptions. This is largely because people want to be nice and to not criticize, something that isn't always ideal. They gloss over these more important questions, such as the assumptions being made, allowing a train of false knowledge to pollute and weaken the knowledge pyramid. I think that the progress of correct physics would be greatly increased if people were willing to question their assumptions in a free and direct fashion. This requires putting the spotlight onto the truly important issues. Here, that requires a separate answer largely focusing on that.

This is especially true because the implied assumptions of a question that an answerer thinks are wrong might actually be legitimate. In other words, the answerer might be wrong. Sometimes, an outsider or a bright eyed, bushy tailed wondering student is the first person to discover that an entire branch of alleged knowledge is actually wrong, and needs a full rework.

How can one ever allow an important discovery to be made if it is hushed up by an arrogant comment or by conclusary reasoning?

Indeed, by reverse logic, if one wanted to impede the progress of awareness of reality, or what was going on, one would intentionally ignore key issues with questions and use conclusory arguments. At the risk of committing the felony here of using an example from outside of physics, have you ever wondered why a lot of politicians often morph questions away from the literal topic and onto another with a phrase like, "The real question is..." This is exactly #4.

Focusing on arguably trivial issues of a question allows for a stronger knowledge pyramid in a tutee's mind. It requires being somewhat irritating, pedantic, and taking a more literal approach in which all parts of the actual question are taken seriously. Keeping within Ohm's Law, a good example of what I mean here to this "literal" approach to answering questions (i.e., not quietly fixing them) is my answer complimenting Thomas' answer here. (I think Thomas glossed over the Maxwell's equations restriction in the answer.) I think that glossing over issues (like this) can create ambiguity in the questioner's mind about the real answer to their real question. Most good students will get hung up on that issue. The teacher will plow onward, but the student won't take it in, and it will be a waste of time. Allowing such ambiguity is building a weak pyramid of knowledge, and against the goals of stackexchange.

In summary, not only because it is in the best interest to the questioner, but also because it is in the best interest to the field of physics, the best approach to an allegedly bad question is probably to have a tutee focus on the alleged issue.

Converting from the tutor-tutee scenario I have invoked to the web-based system here on this site, I think this entails writing a full-fledged answer (option #1) that brings focus to any alleged issues in a question, not in an x-character comment (#3).

• This answer says a lot of very important things but I don't know how relevant it is to a question and answer site like this. Maybe this wasn't clear in what I wrote, but to me "answer the question" means to correct the error, even if that technically doesn't answer what was asked (since the question cannot really be answered). One can't write a full fledged introduction to general relativity in an answer; sometimes "here's why your premise is flawed" is the best you can do. – Javier Jun 24 '18 at 19:20
• Thanks for pointing out that I misunderstood your #1 option. Please review my edited answer. – Jason Arthur Taylor Jun 24 '18 at 20:17
• I disagree with your and AccidentalFourierTransform's beliefs that questions with issues often "cannot really be answered." I think answerers can almost always make good guesses as what is likely an intended question or issue. I called this option #4 in my edited version and option #1 in my first submitted draft. My answer argues that this is wrong path to take unless an appropriate portion of the answer fully justifies the fixing. In other words, the issues should not be glossed over and I am agreeing with your view. – Jason Arthur Taylor Jun 24 '18 at 20:32