So, the hero has found the giant factory belonging to the Big Bad. He enters with his True Companions and finds weapons that could kill thousands or maybe even millions, all built by and being built by the locals. While the hero believes that the locals all knew about the Big Bad's plan and were helping him willingly, a few questions from The Heart clears up the matter — the locals simply think the weapons are harmless machinery that will be used for building houses and/or farming.
This trope describes situations where somebody uses someone to make or do something by lying about what exactly it is that they're doing, or assuring them that it's for the greater good. It could be something as simple as stealing plans or moving an item to another location, or something major, like building a Doomsday Device or breaching a boundary — if the Big Bad plays on their ignorance to make them do something; it's this. This can often result in a HeelFace Turn or My God, What Have I Done?. See also Evil Plan, Nice Job Breaking It, Hero!, Awful Truth, Redemption Equals Death and Ambiguous Innocence. Characters made of Ignorance Is Bliss include the Noble Savage.
- In Black Butler, Ciel tells Snake that his missing friends' whereabouts were unknown and that staying with Ciel is the fastest way to see them again. The reader knows that they were all killed by Ciel's staff when they attempted to ambush the mansion.
- Code Geass: Schneizel tells Nunnally that the residents of Pendragon have been evacuated before nuking it. Cornelia confronts him about it in private where he reveals his grand scheme for Damocles, causing her to turn against him.
- In Kaguya-sama: Love Is War, this plays into the backstory of side character Yu Ishigami. His middle school crush, Kyouko Ootomo, had a seemingly nice boyfriend who revealed himself as a scumbag to Ishigami, promising to give him nudes of the girl and even propositioning for him to have sex with her. Of course the boyfriend gets punched, but Ishigami refuses to tell anybody why to preserve Ootomo's innocence and to avoid the nudes leaking out, leading Ootomo to believe Ishigami was just a jealous creep and the rest of the school to ostracize him. It worked for the most part, with her remaining the cheerful and nice person she was back then.
- Thanos in Avengers: Infinity War expresses this sentiment at least once.
Thanos: You're not the only one cursed with knowledge.
- Diamonds Are Forever: Blofeld kidnaps Willard Whyte and uses his industrial empire to build and launch a Kill Sat. Only one other person in Whyte's organization knows what's going on: the rest are kept ignorant.
- At the start of Van Helsing, Dracula tells Dr. Victor Frankenstein that he provided Victor with a castle and lab equipment, not for scientific advancement, but because he wanted to use Victor's creation for his own ends.
- Cypher in The Matrix decides to betray Morpheus to the Agents. "Ignorance is bliss" is what he uses to justify it when he meets with Agent Smith:
Agent Smith: [He and Cypher are eating at a fancy restaurant] Do we have a deal, Mr. Reagan?Cypher: [cuts a piece of steak and holds it in front of him] You know, I know this steak doesn't exist. I know that when I put it in my mouth, the Matrix is telling my brain that it is juicy and delicious. After nine years, you know what I realize? [Eats the piece of steak and sighs contently] Ignorance is bliss.Agent Smith: Then we have a deal?Cypher: I don't wanna remember nothing. Nothing, you understand? And I want to be rich. You know, someone important like an actor.Agent Smith: Whatever you want, Mr. Reagan.Cypher: Okay. I get my body back into a power plant, re-insert me into the Matrix, I'll get you what you want.Agent Smith: Access codes to the Zion mainframe.Cypher: No, I told you, I don't know them. I can get you the man who does.Agent Smith: Morpheus.
- This, combined with the fact that The World Is Always Doomed, is why the Men in Black go to such lengths to keep up The Masquerade.
- Used in Cabin Fever when the busty brunette suddenly offers herself to the lone surviving hero. She has the killer fever, though she isn't showing any signs yet. Midway through sex, the guy tells her he's worried that they aren't using a condom. So the woman assures him that she's perfectly healthy, because by that point, the only thing that telling the truth could do is spoil their fun.
- In Cafe Setareh, Ebi feels that Fariba and her mother would be better off not knowing that Khosro is dead, so he burns all the newspapers that would tell them.
- In American Gods Wednesday uses Shadow to start a war between the gods so they can conquer the new gods, when in reality, Wednesday and Loki just want the power they'll gain from a field of dead gods.
- The Belgariad: Errand is brought up to be totally innocent so he can sneak into the Rivan throne room to steal the Orb, without knowing what will happen afterwards.
- Star Wars Legends: The Jedi Academy Trilogy reveals that the lead scientist responsible for designing the Death Star and Sun Crusher has no idea that they were used to destroy inhabited planets and star systems, believing them to be intended for large-scale mining projects. Justified in that she was brutally conditioned as a child to take a For Science! view of her work and not think beyond it.
- Harry Harrison's The Stainless Steel Rat. Jim diGriz discovers that the government of the planet Cittanuvo is building a Warlord class battleship under the pretense that it's just a transport ship. After investigating, he finds out that two elite criminals tricked the government into building the ship with the intent of stealing it and using it for interstellar piracy.
- The Howlers in Animorphs routinely wipe out entire species at their master's command so the protagonists assume they must be consumed with rage and enjoy causing destruction. It turns out they think it's all a game.
- In George Orwell's classic dystopia Nineteen Eighty-Four, the last of three core slogans that the Party propagates to the citizens of Oceania is "Ignorance Is Strength". (The other two being "War Is Peace" and "Freedom Is Slavery")
- Ender's Game, because when he goes to the simulator he's actually commanding real troops.
- In Pact, ignorance keeps the vast majority of humans safe from the supernatural by maintaining the Masquerade. As almost all supernatural creatures have been forced over the centuries to swear to abide by the Standard of Solomon, which prevents them from attacking the innocent without cause, this has allowed humanity to expand to its current levels of population, to the point that they reproduce faster than the Others can kill them, Others are steadily being driven from their hiding places by ignorant humans against whom they can't fight back, and those few that can are dealt with by the few humans that know the truth.
- In Glee, Sue gets Brittany to give her the set list for New Directions, but Brittany has no clue about what she's going to do with it.
- NCIS: In 6.21, "Toxic", Abby builds a biological weapon without knowing what it is.
- In Dollhouse, it turns out the Evil Corporation is building a Doomsday Device by making each of their research departments around the world build a little part of it, and nobody knowing about the larger picture.
- House had an episode called "Ignorance Is Bliss" where it turned out that the Patient of the Week (who was a genius) was regularly taking cough medicine so he would be around the same intelligence level as his girlfriend.
- The Dark Curse in Once Upon a Time exiled characters from a fairy tale world into the real world with new memories. Considering nearly all of them have ridiculously tragic back stories, sometimes not knowing is a blessing. As Ruby puts it:
Ruby/Red Riding Hood: Regina thought she was punishing us by erasing who we were. She underestimated just how much crap we wanted to forget.
- In season six of Supernatural, we see Castiel take on the souls of Purgatory, without having any idea of the consequences. It is later revealed that he has taken on millions of Leviathan souls, who later become a Big Bad.
- Altered Carbon: It turns out that Laurens Bancroft really did kill himself. He murdered a prostitute while violently raping her (not just her current body; he smashed her stack too) and caused another one to run away and jump to her death. He felt so ashamed that he shot himself, knowing that he would simply wake up in a new body with no memory of his actions.
- "The Wingmen" by Dos Gringos contains the line:
We're the wingmen and there's no better life than this,
For knowledge is the power, but ignorance is bliss
- "Ignorance is Bliss" by Jellyfish has the line for every end of chorus.
Princess Toadstool, I know you're frightened, mm-mmm,
But if you knew just why you're here, your fear would just be heightened. So lets just say...
Ignorance is bliss!
- Up to several Nightwish song express this sentiment, without quoting it verbatim.
- Bloodborne:This is a gameplay mechanic. Instead of Humanity, your character gains Insight on the way Otherworldly beings see Yarnham. By observing them with your insight, new enemies appear and old enemies gain advanced attacks.
- Spyro: Year of the Dragon: Bianca helps the Sorceress abduct the dragon eggs thinking they'll be raised in the Forgotten Worlds, which will stop all magic disappearing from her home - the Sorceress really plans to kill the dragons and take their wings for a spell.
- In Metal Gear Solid, Otacon designed Metal Gear REX under the assumption that it would be used as a mobile TMD to destroy incoming missiles - he had no idea that his employers would arm it with nukes instead.
- This is probably the one and only Pet the Dog moment from Matt Engarde in Phoenix Wright: Ace Attorney - Justice for All:
Engarde: (Sigh)... I thought if you didn't know, maybe you wouldn't feel so bad for doing your job...
- In Alice: Madness Returns, the loading screen may give this piece of advice: "Ignorance is bliss, except when it's fatal."
- This turns out to be central to the plot. Dr. Bumby wants to take away Alice's memories so that he can pimp her out like he's done to other girls.
- The motivation behind Ryoji asking you to kill him in Persona 3. Nyx is coming to destroy the world, and it's generally believed that there's no way to stop it. Killing Ryoji will eliminate the Dark Hour and erase any associated memories, leaving the world to live out what's left of its life in peace.
- The one of the main themes of Persona 4 is about how humans desire a peaceful lie instead of accepting any harsh truths. Major turning points are centered around the cast rejecting the lies, which eventually clears the supernatural fog plaguing the town.
- Played in a far darker variant in Shin Megami Tensei IV. The Archangels' idea of a peaceful, harmonious Mikado is one where literacy, education, and worship or even mere admiration of anyone besides God doesn't exist. You help achieve this in the Law ending.
- Referenced in Planescape: Torment, when Morte tells a story about a man who suddenly finds himself with no memories at all. An old hag appears before him and asks him for his third wish, and he replies that he hasn't had a first or second wish yet. The hag tells him that his second wish was to undo his first wish, which is why he doesn't remember making any wishes. The man, though clearly skeptical, nevertheless wishes to remember who he is. The hag bursts out laughing and grants his wish before disappearing forever. "Funny... that was your first wish."
- RuneScape has this in the quests "Priest in Peril" and "Devious Minds".
- In World of Warcraft Horde-players visiting Dragonblight are offered a questline to help the Forsaken gather ingredients for a plague that will inevitably wipe out the scourge, which Puttress later uses to kill, not only scourge-soldiers, but also the combined army of humans and orcs battling them.
- In Star Control 2, ignorance is not only bliss, but armor. The Arilou hint at a malicious presence from Beyond, but refuse to elaborate further when asked, claiming that ignorance is the best protection against Them, as They can not see mankind unless mankind show themselves.
Arilou: They have names, but you do not know them. They would like to find you, but they cannot see you, unless you show yourselves. In a way, ignorance is your best protection. If I tell you more, you will be able to look where you could never look before, and while looking you can and will be seen. You do not want to be seen.
- Close Your Eyes implies this by the storyline and its multiple endings, especially the "Best Ending", where the V.I.E.W facility self-destructs, killing Cecily, the Witch, and the Husks and the subtitle being, "Everyone closed their eyes".
- Little Busters!:
- In Komari's route, when Riki learns that her brother Takuya is dead, he initially believes that the best option would be to keep her in the dark so she wouldn't be saddened by learning the truth. Riki can either continue keeping her in the dark, which leads to the bad end of her route, or subvert this trope and help her face the truth behind Takuya's death head-on.
- In Refrain, Kengo wants to keep Riki and Rin in the dark about the bus crash that would've killed everyone else, and keep the "Groundhog Day" Loop running forever, as he worries that the two of them wouldn't be able to get by after everyone else they knew died, and he would be able to have fun with everyone else.
- A Day With Bowser Jr: In Two Koopas for a throne (part 1), Larry overhears a snippet of a conversation that hints at the Koopalings' true origins, but chooses to forget having heard it because he feels he'd be happier not knowing.
- Fighter of 8-Bit Theater is an example of this. The other Light Warriors often get him to do things by convincing him it is for the greater good. There's also the fact that he still believes they're heroes after all the untold damage they've caused.
- The Inexplicable Adventures of Bob!: In an uncharacteristically manipulative moment, in her second appearance, Voluptua lets Bob fly off on what he thinks is a very simple mission, while she suspects an alien supercriminal ''just might'' be waiting for him.
- In Bob and George, until George explains the danger, Megaman is not worried.
- Cecil of Welcome to Night Vale cheerfully reports the obviously bogus coverup stories concocted by the City Council with little to no indication that he doesn't believe every word. Also, choosing not to question what one is told seems to be the only way to survive living in Night Vale.
"Ignorance may not actually be bliss, but it certainly is less work."
- In his vlogs for Avatar: The Last Airbender, Doug Walker defended this trope as, sometimes, if you want to keep surviving and feeling sane, then you have to force yourself to stay in the dark about stuff.
- Haven't you heard? A picture's worth a thousand words.
- Gravity Falls gives us the Society Of The Blind Eye, who believe in this and enforce it with Laser-Guided Amnesia.
- In Love, Death & Robots: Beyond the Aquila Rift, Greta insists that Thom can't handle the truth about his real situation. And she's right. Thom is in reality in an alien hive light years away from any chance of rescue and "Greta" is really a revolting, oozing giant spider-like alien. He screams at her in horror when he sees her and so she knocks him out and puts him back in the illusory world after wiping his memory. The small comfort is she seems genuinely like a Non-Malicious Monster.