Example 1: Anecdote (couldn't find reference online) Designers of astronaut suits struggled with knee/elbow joints... until someone ELSE told them of the armor of (I think) Henry VIII.

Example 2: An irrigation system fails because the designer had not known about phenomena (and thus their countermeasures, already in use elsewhere) that occur in those specific circumstances (geological, or wildlife, etc).

Example 3: [edit: removed, misleading]

Example 4: Searching for inexpensive but hard containers for microsculpture tools / works-in-progress, spending months rejecting tool boxes and solutions for modellers and hobbyist jewelry makers, finally settling for a DIY solution... and years later learning of the very low wholesale price of single-use medical equipment like PP vials, especially Eppendorfs

Example 5: Product designers trying to avoid infringing on patents: must first find anything potentially related before addressing it.
5.a) Being sued because the patent infringed on was on an algorithm used in a totally different branch of industry

Example 6: The intention behind an "Is there anything else I should know about" question

Example 7: Trying to find out whether "an" is the correct artcle to use before the quoted part in Example 6, without knowing the name of the grammatical role that part plays, whether it is an exception, etc - reducing the effort to browsing in hopes of finding a similar enough example

Example 8: Spending 60 hours searching for the official name of this phenomenon, asking around, reading Wikipedia (starting from "logic", "information", "knowledge", "paradox", ...), judging it salient enough to be named - though just maybe not, and how am I to know?

[edit] The emphasis is NOT on unpredictability, but on information/knowledge already extant, known to someone, somewhere, being very difficult (short of chance or external input) to find because you can't know the questions to ask without already having some knowledge of the answer.

  • 2
    Sadly there is no antonym for serendipity.
    – Bookeater
    Commented Feb 21, 2016 at 11:09
  • 1
    Not an phrase in use but "Outside Context Knowledge" (variation of Outside Context Problem) seems appropriate. Commented Feb 21, 2016 at 13:05
  • 1
    An idiomatic expression for this is "not knowing where to begin looking for an answer."
    – zwol
    Commented Feb 21, 2016 at 19:02
  • @zwol or that there is an answer to search for. Or a problem in the first place.
    – kaay
    Commented Feb 21, 2016 at 19:05

9 Answers 9


The exact thing you are looking for is called the Relevance Paradox. The wiki actually includes your irrigation example.

The relevance paradox describes an attempt to gather information relevant to a decision, which fails because the elimination of information perceived as distracting or unnecessary and thus detrimental to making an optimal decision, can also inadvertently exclude information that is actually crucial.

When searching for knowledge - of which there is really quite a lot - one doesn't search for things that do not seem to apply to the situation. So, when searching for information, you first try to establish what items would be relevant to the matter at hand. But, starting from the point of having no information, you are likely to be missing information that would make the relevance of another piece of information obvious.

  • 1
    A link to the article or its definition would be nice.
    – Mari-Lou A
    Commented Feb 22, 2016 at 10:33
  • 1
    @Mari-LouA, I am stuck at work and on my phone, but there's a sunyit.edu link that's the first google hit. Its a wiki article - could some kindly bystander edit that in?
    – user161546
    Commented Feb 22, 2016 at 13:16
  • 1
    Here is an undeletion request for this Wikipedia article. If anyone has anything to add, please do.
    – kaay
    Commented Feb 29, 2016 at 21:55
  • 1
    To those reading this some years after the answer - it seems that, although this answer was the correct one the question author was seeking, the Relevance Paradox is having a difficult time remaining in the major knowledge repositories. I have updated the link to the least objectionable source I could find at the time of this writing. Learners should be aware that my answer is acceptable from a language learning perspective, but may be out of date academically, as I am having trouble finding more references to support it, or a concept that may or may not be slowly replacing it.
    – user161546
    Commented Sep 8, 2022 at 2:43
  • 1
    The irony of the Relevance Paradox possibly becoming lost knowledge (by it's own mechanisms!) has me staring at a wall and pondering the nature of human knowledge, and indeed, the reality in which we exist.
    – user161546
    Commented Sep 8, 2022 at 2:53

Not sure if I understand your question 100 percent, but here goes my take.

One sometimes distinguishes between known unknowns and unknown unknowns. For example, if you're planning a mission to Mars, you may not know the speed of wind on your landing spot, that would be a known unknown. But there will also be circumstances/phenomena which you simply cannot foresee. Those would be unknown unknowns.

Perhaps you could somehow use the latter?

  • 6
    Perfect (was just about to post this myself)! Of course credit should go to Donald Rumsfeld for immortalizing these phrases: en.wikipedia.org/wiki/There_are_known_knowns
    – user152004
    Commented Feb 21, 2016 at 8:55
  • Forgot about unknown unknowns... yet it doesn't quite match my intention. But you've helped me clarify the question, thank you.
    – kaay
    Commented Feb 21, 2016 at 10:47
  • I do, of course, acknowledge that this might still be the closest answer there is, if no-one has named what I have in mind... unknown knowns?
    – kaay
    Commented Feb 21, 2016 at 10:59
  • OK, not unknown knowns - unless Slavoj Žižek agrees to put quotes around "unknown" when using his definition (or "unacknowledged knowledge", it sounds more appropriate).
    – kaay
    Commented Feb 21, 2016 at 11:17
  • 1
    Make that 10k rep :D
    – ThreeFx
    Commented Feb 21, 2016 at 23:11

The learner's paradox is that in order to learn about something, you must first know that thing. As Socrates puts it:
[A] man cannot search either for what he knows or for what he does not know[.] He cannot search for what he knows--since he knows it, there is no need to search--nor for what he does not know, for he does not know what to look for. –Quora.com

  • This paradox (which leads to the concept of anamnesis) leads Plato into a whole load of weird arguments: since we can never learn something we didn't know, our soul must have existed since the beginning of time already knowing everything. So invoking it might be a bit confusing if you just want the OP's meaning
    – Stuart F
    Commented Sep 8, 2022 at 8:33

The emphasis is NOT on unpredictability, but on information/knowledge already extant, known to someone, somewhere, being very difficult (short of chance or external input) to find because you can't know the questions to ask without already having some knowledge of the answer.

It sounds like the researcher's version of bootstrapping, a term used in linguistics as well as in relation to computer operating systems. Since it's a general term, it can be applied to the questions you're asking about as well, where you need a little information to get more.

In literal terms, a bootstrap is the small strap on a boot that is used to help pull on the entire boot. Similarly in computer science, booting refers to the startup of an operation system by means of first initiating a smaller program. Therefore, bootstrapping is a general term used to refer to the leveraging of a small action into a more powerful and significant operation. - wikipedia

  • Related, yes - but it's more about the growth of complexity out of a basic seed, than the inability to know about the seeds without having them already.
    – kaay
    Commented Feb 21, 2016 at 11:33
  • 1
    @kaay That's an ambiguous statement - I think you're referring to bootstrapping by your growth of complexity reference, not the inability to know reference, but let me know if you meant the opposite. The idea I was trying to get at with bootstrapping was that you need to have the seed to do anything - no seed, no progress. To take your example 8, you can now use the term bootstrap to start the search for related words (perhaps something along the lines of recursive knowledge).
    – Lawrence
    Commented Feb 21, 2016 at 11:56

I have always thought the phrase inelegant but you can't know what you don't know or you don't know what you don't know is often used sympathetically to someone pleading ignorance.

This stackexchange questionhas more information about the use of the phrase.


Sounds like you have a conceptual metaphor mapping problem. A conceptual metaphor is the overlay of one concept or idea on a completely different subject area. The problem you have identified is a difficulty in making that cognitive leap from one subject area to another because of a lack of initial connection between the two fields. You lack a "link" hence it is a mapping problem.


I think you are asking for the combination of someone who is uninitiated bumping into something that is obscure but essential.



You might call this Domain Knowledge, or the Problem Domain. Domain Knowledge refers to information generally only known by people who are experts in the field, even if that information might be of use to people in other fields, who might not even know enough to know what to ask. Determining the Problem Domain for any given problem may be impossible without the appropriate experts in the field, and it may be impossible for those not in the field to even know which experts are needed.


I searched "unserendipitous" and found a crossword reference to HAPLESS. That seems appropriate, although if you're looking to coin a word: help-less?

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