History Main / LostCommonKnowledge

->'''Armin:''' "According to the book, the majority of this world is covered by water called the "sea"!! And it says the "sea" is all salt water!!
->'''Eren:''' Salt?! L-liar!! I mean, salt?! That would be a treasure trove! Merchants would've already exhausted the supply!!
->'''Armin:''' No, that's the thing! The "sea" is so huge, it can't be depleted!
->'''Eren:''' [[RealityIsUnrealistic That's just silly.]]
-->--''Manga/AttackOnTitan''

* In ''WesternAnimation/{{WALL-E}}'', when Captain [=McCrea=] (whose ancestors spent hundreds of years lounging around on the luxury space-ship ''Axiom'' after fleeing Earth) accesses the computer database, most of the facts he's getting all excited over are commonplace knowledge in the real world, like the definition of "dancing" and "farms."

Compare FutureImperfect, where the knowledge is still there but has been misinterpeted over the years.

* In ''Franchise/Bionicle'', the Matoran on Mata Nui use to live in the city of Metru Nui, but they lost all their memories of their old lives when the Makuta trapped them all wiped their memories so he could control them when they awaken. The Toa Metru awaken the Matoran by giving up their Toa powers, and guide them in tribal living as Turaga.

* In ''WesternAnimation/{{WALL-E}}'', when the ship's captain accesses the computer database, most of the facts he's getting all excited over are commonplace knowledge in the real world, like the definition of "dancing" and "farms."

* The page quote is from ''Manga/AttackOnTitan'' which takes place InAWorld where the last remnants of humanity are holed up in a walled city, hiding in fear of the people-eating giants that have overrun the world. Information about the outside world is not only scarce — it's ''forbidden'' by the government, and Eren mentions that the book Armin is reading from is illegal to own.

* ''Film/BattlefieldEarth'' uses this a lot.

* In ''Film/TheBookOfEli'', all copies of the Bible have been destroyed, to the point where a big driving force of the plot is various characters' attempts to protect or steal a rare surviving copy. Explained as after a terrible third world war nearly drove humanity to extinction, most of humanity decided that religion was to blame for all the world's ills and all religious texts were burnt. [[spoiler: The ending reveals that Alcatraz has been converted into a printing factory, where some individuals protect and feverishly work to reprint any salvaged copies of the Bible, Qu'ran, Talmud etc.]]

* In ''Film/TheBookOfEli'', all copies of the Bible have been destroyed, to the point where a big driving force of the plot is various characters' attempts to protect or steal a rare surviving copy. For reference, there are 2.5+ billion copies of the book in existence with more printed daily. Explained as after a terrible third world war nearly drove humanity to extinction, humanity decided that religion was to blame for all the world's ills and all religious texts were burnt.

* In ''Film/TheBookOfEli'', all copies of [[spoiler: the Bible]] have been destroyed, to the point where a big driving force of the plot is various characters' attempts to protect or steal a rare surviving copy.
** For reference, there are [[spoiler:2.5+ billion copies of the book in existence with more printed daily]].

-->--''Manga/ShingekiNoKyojin''

* The page quote is from ''Manga/ShingekiNoKyojin'' which takes place InAWorld where the last remnants of humanity are holed up in a walled city, hiding in fear of the people-eating giants that have overrun the world. Information about the outside world is not only scarce — it's ''forbidden'' by the government, and Eren mentions that the book Armin is reading from is illegal to own.

* Taken to an extreme in Ayn Rand's novella "Anthem"- the hero protagonist rediscovers the very concept of individuality and the word "I".
* In the {{dystopia}}n world of the DeliriumSeries, where love is considered a disease, the protagonist Lena does not know what poetry is. She considers it to be incredibly beautiful when she hears it, however.

* A joke from [[CommieLand Communsit Eastern Europe]]: Somewhen in TheFuture, a child reads in an old book about butter. The child asks all people for the meaning, but nobody can remember. Finally, they find a definition in a dictionary: "A spread for bread, not used anymore by progressive people for its connotation with capitalism."

-->''''Man 1:''' What's normal to him amazes us.\\

-->--''AttackOnTitan''

* The page quote is from ''[[Manga/ShingekiNoKyojin Attack on Titan]]'' which takes place InAWorld where the last remnants of humanity are holed up in a walled city, hiding in fear of the people-eating giants that have overrun the world. Information about the outside world is not only scarce — it's ''forbidden'' by the government, and Eren mentions that the book Armin is reading from is illegal to own.

* "The Quiz Broadcast" on ''ThatMitchellAndWebbLook'' is a post-apocalyptic gameshow that plays this for laughs. For example: "Pre-Event sources talk about "hope". What was hope?"

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* The page quote is from ''AttackOnTitan'' which takes place InAWorld where the last remnants of humanity are holed up in a walled city, hiding in fear of the people-eating giants that have overrun the world. Information about the outside world is not only scarce — it's ''forbidden'' by the government, and Eren mentions that the book Armin is reading from is illegal to own.

* In ''TheBookOfEli'', all copies of [[spoiler: the Bible]] have been destroyed, to the point where a big driving force of the plot is various characters' attempts to protect or steal a rare surviving copy.
* In {{WALLE}}, when the ship's captain accesses the computer database, most of the facts he's getting all excited over are commonplace knowledge in the real world, like the definition of "dancing" and "farms."
* ''BattlefieldEarth'' uses this a lot.
* Played for laughs in ''{{Film/Sleeper}}''. Miles Monroe wakes up in the year 2173 after spending 200 years as a HumanPopsicle. The people of that time have lost most of their historical knowledge due to a nuclear war, so they ask him questions about 20th century artifacts (e.g. "chattering teeth") and people. Miles makes up a bunch of lies about them for his own amusement ("Bela Lugosi...was the mayor of New York for a while." and "Charles de Gaulle...was a very famous French chef."}.

[[folder:LiveActionTV]]

[[folder:WesternAnimation]]
* In ''WesternAnimation/PeaceOnEarth'', two squirrel pups ask their grandfather what "men" are, since humans have driven themselves to extinction.
* Often played for laughs in ''{{Futurama}}'':

-->Man 1: What's normal to him amazes us.
-->Man 2: He will be our new god.

* * Often played for laughs in ''{{Futurama}}'':

* * Played for laughs in ''{{Film/Sleeper}}''. Miles Monroe wakes up in the year 2173 after spending 200 years as a HumanPopsicle. The people of that time have lost most of their historical knowledge due to a nuclear war, so they ask him questions about 20th century artifacts (e.g. "chattering teeth") and people. Miles makes up a bunch of lies about them for his own amusement ("Bela Lugosi...was the mayor of New York for a while." and "Charles de Gaulle...was a very famous French chef."}.