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    The article advocates asking “why?” instead of merely “how?” (and “what?”), but doesn’t answer any of these questions. I thought I’d at least see an image.

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      Added in edit: I’m getting a lot of mis-understanding, and I really don’t know what to do to ask the question differently. But the down-votes (off-topic) are clear, so I’ll go away and re-think this. I still believe the question I’m trying to ask is relevant and on-topic, so perhaps I’m just not being clear about what the question is.

      The response has given me much to think about. In particular, I guess I need to read more here to try to work out what the audience is. It would seem that thought-experiments of this type aren’t welcome. Fair enough.


      I don’t understand your criticism.

      Yes, the article is asking why. The point is that this is a question that requires either thought or experiment. To provide an answer in the article, or an image of the result, defeats the entire purpose of the question. If you want to know what the result is you can either follow the link in the article, or you can do the experiment.

      But some people might choose to think about this for themselves, and giving the answer would prevent that.

      And the question is about the why. Everyone I ever ask seems simply to do the experiment, look up the answer, or tell me how a photocopier works. I was hoping someone would be able to reason out the why you get the result you do, not simply tell me how the copier achieves the result it does.

      Clearly I’m just not asking the question correctly - only one person has ever understood what I’m trying to ask, and I don’t understand why that’s the case.

      Deeply frustrating - I was hoping for more from the Lobsters community. But I see now that there are two downvotes, marking this as “off-topic”. I thought this was sufficiently intellectually engaging, but I guess I’ve misjudged the audience.

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        I found the title misleading. If it had read “Don’t just ask how — ask why”, and then used the mirror photocopy question as an example, that would be one thing. But when I see a headline asking a question, I expect the article to answer it, and this case I was left disappointed.

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          That’s really interesting. When I see an article asking a question I expect it to be discussed and not necessarily answered. I wouldn’t have expected people to expect articles always to answer the questions in their titles.

          Useful to see the different perspective. Thank you.

          Edit: In case an article intends to pose a question without answering it, how should it be entitled?

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          The question you are asking absolutely requires knowing how a photocopier or scanner works. There’s no deeper philosophical question involved.

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            The entire point about this question is that I disagree with you here. I believe it is possible to deduce the result without knowing how a copier works, only by knowing its desired behaviour. That is the point of the thought-experiment, and obviously I’ve not made that clear enough.

            So let me say this: knowing only what a copier is intended to do, and without knowing anything about how it works, can you, through various thought-experiments, deduce what you must get if you copy a mirror?

            I believe it’s possible.

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              You get whatever that mirror was reflecting at the time. In this case, some part of the inside of the photocopier.

              If there is a deeper point beyond that, it’s lost on me.

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                You get whatever that mirror was reflecting at the time.

                That turns out not to be the case, and I believe that even knowing nothing more than what a copier is supposed to accomplish, it’s possible via thought-experiments to deduce that. The reasoning is quite tricky, in places subtle, and I’m not convinced my argument is completely water-tight, and that’s why I believe this question is deeper than most people think.

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                  The only subtlety is that the lighsource is angled. My first guess would have been a white mirror surface because I though the light source was parallell to the surface, but of course that would have prevented the CCD from being on the same axis.

                  In any case, it devolves into the technical details on how to implement a photocopier. Mildly interesting, I learned something today.

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                    Certainly it does lead to the question of how to implement a photocopier, but there is still more going on before that. If you implement a good photocopier, is it an unavoidable consequence that they all give the same result when you copy a mirror?

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                    Eh, that is the case, it just happens to be that because of how the picture is pieced together over time, that reflection is always away from the light.

                    I think the reflective nature of graphite plays a role here as a forcing function in copier design

                    I’m now actually curious to see what chain of reasoning you’ve applied to this.

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                      You have a message.

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              It’s very much off-topic as it has nothing to do with computing.

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                Not directly, no, I agree, and I admit that I didn’t realise that this site is so specifically focussed only on computing. Having said that, my colleagues were intrigued by my approach to this problem. As mentioned in another comment, it’s not actually anything to do with how a photocopier works. It’s about deducing behaviour in an unknown context purely from knowing the overall desired behaviour of a system.

                As such I’d’ve thought it was squarely in the realm of the sort of thing programmers would occasionally have to do, and hence of interest.

                The options are (a) I was wrong, or (b) I’ve still not figured out how to ask the question in a way that makes it clear what the real question is, or (c) something else.

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            Fun article. I don’t get the blowback.