What did you get told as a child that you realised was a lie as you got older?

If you work hard you'll have a successful life
- See also: "get good grades in university and you'll be flooded with job offers!"
  
  That wasn't a lie, exactly, it was just Baby Boomers not realizing how much the world changed since they were in school. It used to happen that way. My mother got her first job out of school when the employer came to campus to recruit through a job fair.
  
  It's just an overly positive way of saying, "If you don't get good grades in uni, many HRs will de-list you before looking at your resume".
- Relevant quote:
  If wealth was the inevitable result of hard work and enterprise, every woman in Africa would be a millionaire
  George Monbiot
- I don't think it's a lie, just outdated and obsolete advice.
- We're laughing will Ferrell.gif

God exists and watches everything you do and loves you while threatening you with eternal damnation.
- And he's terrible with money! He needs more money!
  George Carlin, how we miss thee.
  https://youtu.be/QZ8hefESt7c?si=I5xZByn7o1UWcsbv
  
  Here is an alternative Piped link(s):
  https://piped.video/QZ8hefESt7c?si=I5xZByn7o1UWcsbv
  Piped is a privacy-respecting open-source alternative frontend to YouTube.
  I'm open-source; check me out at GitHub.
- You're allowed to be atheist of course, but do you have any more proof that there are no gods than they have that gods exist?
  EDIT: Y'all can have your opinion, no one's questioning that. You're allowed to believe there are no higher powers, but I'm not allowed my personal belief that there is?? Not one person has provided proof that there is no Higher Power. Grow up....
  
  I'm not against religion, but that's not how evidence and proof works. Do you have any proof that tiny invisible pink elephants aren't hiding in your fridge?
  
  That's not really how it works though. If I tell you there's an invisible dragon living under your bed who will burn your house down at some time in the future if you don't give me $10. You can't disprove it, but because I'm the one making the claim that the dragon exists the burden of proof is on me.
  
  You should familiarize yourself with the concept called Burden of Proof. They (those who believe in God, and claim he exists and created all things, etc) are the ones where the burden lies. It is not for the rest of us to prove their beliefs for them, or you.
  
  The default position is that we don't know if a specified thing exists. To prove or disprove it, you need evidence. I can prove that the Christian God doesn't exist, as it is logically impossible, but it's possible that some other version of a god might exist, I don't know. I don't have evidence either way.
  
  Let’s start with clarifying an element of the question:
  Which characteristics define a god? Do these characteristics violate the laws of physics and/or internal logic? If these characteristics do not violate the laws of physics, then what aspects distinguish a god from a mundane or natural entity?
  Edit: I have since disavowed this instance
  
  "A fire-breathing dragon lives in my garage"
  
  Not one person has provided proof that there is no Higher Power. Grow up....
  Because that's not the atheist position. You're wrestling with a claim nobody is making.
  Atheism doesn't claim there is no "Higher Power", it's just a disbelief in theistic claims.
  
  Careful, many online atheists don't understand that they have to prove a negative. That they have to prove the assertion: "There is no god."
  The default position is that there is yet insufficient evidence to draw a conclusion.
  Edit: Thank you for the downvotes, you have provided me with further evidence that online atheists don't understand that they have to prove a negative. Your butthurt fuels me.

When I was a little kid, I asked my grandfather what the bumps in the middle of the road (the reflectors) were for. He told me that it was so blind people could drive. It made perfect sense to me, and I believed that for longer than I should have!
- Your grandfather sounds rad
  
  They’re called Bott’s dots! Most places where it snows don’t have them because they don’t survive ploughing.

"you're not going to carry a calculator with you everywhere"
- The thing is I believe that statement is a bit misunderstood.
  Calculators were already becoming pocket sized back in the day, but using it to calculate things if you don't know how to use it is where the actual problem is.
  Hence the reasoning to learn how to math vs only having the device.
  
  Calculators were already becoming pocket sized back in the day…
  True, but I can count on 0 hands how many people I knew carried one in their pocket.
  Now if the calculator were built into a beeper, everyone would have had one.
  
  I'm not saying I disagree, but I had a different experience.
  
  it's very easy to enter wrong numbers on a calculator, but you need some basic reasoning and familiarity to know when an answer is off, and you need to start over
  
  I don’t think people realised how quickly tech would advance.
  
  Yeah, in my experience "You won't carry a calculator with you everywhere you go" was what they said to justify pointless busywork.
- You may carry one now, but can you calculate percentages on it without your maths lessons? Can you convert fractions? I blame the technology, if it's going to math it needs to math all maths
  
  Frankly, these days? Yeah you totally can. "Hey Siri, what's 3% of 235,889?" or "Hey Siri, what's 8/37ths converted to 300ths?" will most likely just feed you a correct answer.
- And you might not have a smartphone or smartwatch with you. I've seen people who needed a calculator to do basic math.

"Girls desire a knight in shining armor to come sweep them off their feet!" — my pastor
For the longest time, I struggled because I was told all my life what a "woman's purpose" was, and my desires never lined up with that. Felt like a freak because I never desired romance, sex, or partnership with a man (or anyone else, for that matter). If that was my purpose, was I supposed to will myself to want that for myself? Was I doomed to be alone forever? Was I wrong to want to pursue adventure and things that I wanted?
If my desire ≠ God's desire (which was apparently union with a man at some point in the future), then my desires were.. wrong. Maybe/probably even evil.
So I fucked up my life trying to follow that and fit into that mold. I did things I never wanted to do because it was the "right thing" to do in the eyes of God.
After I escaped, I never really recovered. But.. I discovered a lot about myself.
I did bearded dragon rescues & fostering, I got into cosplay, learned how to sew stuffed animals, got some mental health care, rekindled my love for nature.. all by myself. I learned to love me and not base my worth on what other folks believe I should do or how I should behave. I don't have a partner who gets to dictate my personality. I got to grow on my own.
I'm still coming to terms with.. a lot of things about myself, but now I'm able to grow freely instead of being confined to such a small pot.
Don't let people define who or what you are, or what your purpose is in life. Only you get to do that. It's both terrifying and freeing, but you can do this.
- Even for those us who fit into the straight/white/cis mould, learning how to create purpose and meaning for yourself is a really hard battle against expectations imposed growing up. Thanks for sharing a really wholesome story :)

get a good education and work hard and you will be rewarded.

all colors can be made from red, yellow, and blue
how an airfoil works
language is immutable
you won't always have a calculator in your pocket
infinite growth is sustainable
- language is immutable
  No, it changes with what's popular. It's so fetch.
  
  Stop trying to make fetch happen.
- The first one seems OK as it’s the basis of CMYK colour printing? Obviously missing black of course though.
  
  The color people will tell you that cyan and magenta do not equal red and blue. My university advisor tricked me into taking a 400 level class from the college of art and design on color theory. Really interesting class but an insane amount of work. Very early on the professor told us to throw out any book that identified red, yellow, and blue as the primary colors. It’s red, green, blue for light or cyan, magenta, yellow for pigment.
  
  I see you've been tricked by their lies. Blue is sorta close to cyan, and red is kinda close to magenta, but they're not the same.
  If someone tells you that you can make any other color from RYB, ask them to make magenta. Doesn't work.
  
  Cyan is not blue and magenta is not red.
  
  Black in CMYK is not strictly necessary, you can absolutely make black out of CMY, but the separate ink gets added since black is such a regular occurence it's simply cheaper to not mix it out of the other colors.
  
  In CMY (printing) you get black by adding them all. In RGB (lighting) you get white

That republicans are better on the economy. Nah it turns out they consistently screw it up by every measure.
- It's like saying tapeworms are good for your nutrition
- Yeah that was a persistent "it's just generally known" type of thing in the area where I grew up.

Basically everything my mother ever said. I repeat a lot of it back to her now, and she always asks, “where did you hear such absurdities?”
- Ohhhhhhh how good that must feel.
  
  "I never said that!"
- "that's not what I remember" "That's not how I remember it" "You must be remembering it wrong" "I would never say that"

That you should base your diet on carbohydrates, and minimise fat intake.
- Wait why the f the base is full chok of calories? Is this *how to get child obesity " manual?
  
  Had to learn this pyramid but never applied it. I mean, what did people eat for millions of years? Grains, roots, vegetables and fruits from foraging and now and then a ton of flesh (you can count dairy as extra-fatty flesh). So a lot of full-grain, vegetables and inbetween fruits and once or twice the week flesh and dairy it is for me.

That I'd never have a calculator in my pocket
That I'd get more conservative as I grew older
- People who gain/have a lot of wealth over their life do tend to want to lock that wealth in by being Conservative I think. Wouldn't want to shake things up!
- I didn't get more conservative as I grew older. At least I don't think I did. What happened is that the definition of conservative changed.
  Criticizing censorship and restrictions on free speech didn't use to be a conservative cause, it is now, so I grew "more conservative" without any of my beliefs changing.
  
  Conservatives are still quick to suppress speech they don't agree with, though. Their criticism of censorship isn't a cause, it's a smokescreen.
- That saying holds more truth if you're using the "non-political" definitions of conservative -- i.e. moderate, cautious, or resistant to change.
  Moreso "set in your ways" as the world changes around you.
  
  I suppose this is true, but remaining set in your ways while the world changes, taken to it's logical conclusion is political conservatism/fascism
- People who aren't liberal when they're young have no heart.
  People who aren't conservative when they're old have no money.
  
  There are multiple things wrong with this, the most glaring of which is that a conservative with money would lack a heart as well. Conservatism is incompatible with having a heart.

That if a racoon saw you swimming, it would swim out to you and sit on your head and drown you.
My fully adult mother actually feared this was something that could happen to her children, and she warned us of this “danger” every summer when we were young.
- This is awfully specific, haha.
- Those goddamn racoons!
- If that were true I’d go swimming a lot more often!

I was raised christian so basically everything I was ever told was an absolute lie.
- Same here friend. But they were lies Their parents told them and so on and so on so it's understandable how they thought they were doing the right thing.
- True dat but its fairly easy to see through that nonsense and realise your parents are idiots (at best), one of the trials of growing up. Assuming there are no repercussions for it, like death, banishmanet etc
- ⚠️ controversial
- ⚠️ controversial
- Spoiler alert: it probably wasn't
  
  spoiler alert: it factually was. Go thump your bible elsewhere, Ive been deprogrammed already

Me parent convinced a few of friends that the ice cream truck only played music when it was OUT of ice cream
- Haha thats awesome

When you grow up everything you write will need to be in cursive.
- On the plus side, I have a pretty bangin' signature. On the minus side, they wasted a good chunk of lesson time teaching a useless script. Fortunately it was on the way out already, so I was never really required to use it even in school.
  
  Millennial here and I haven’t yet seen a non-cursive self-identifying signature. Are they just like bubbly high-school antics and hearts dotting the letter i?

" you can be whatever you want to be"
- The real truth of it is: Through persistent action and discipline, you can dramatically increase the probability that you can be what you want to be.
  I always use the lottery analogy with my kids: “How many lottery tickets did you get today?”.
  The second part of the truth is: Some people come with a lot more lottery tickets that you, through genetics, income background, family support and, yes, luck. Don’t let that stop you; most don’t and you don’t need to be first to win this race.

Police are there to help
- Depends on where you live it seems
  
  Where do you recon they are helping? Out of three countries I've lived in, they are either useless or just simply ACAB.
- Police are there to help *maintain the status quo
  Fixed

Over thirty years ago, I told a friend of a friend “Australians come from Australia, Romanians come from Romania, therefore Canadians come from Canadia”. She’s been calling it “Canadia” for thirty years.
We’ve been together for ten years now, and she’s just found out that it’s not called “Canadia”. Boy am I in trouble.
- ...i relish saying canadia; it rolls so deliciously off the tongue that i can't resist using at every opportunity...

Christopher Columbus set out to prove that the Earth was round after eating an orange or something and that's how jesus discovered America
- Wait, what‽
  
  Mormon?
  
  yea they taught this in school in the us
- You probably had the same damn book I did, with an illustration of him eating an orange and seeing the wings of a butterfly coming up over it and supposedly realizing they look just like the sails of a ship and so, gasp, the world must be round like this orange!
  
  yes Christopher Colombus exactly

Everything's gonna be ok.
Trust me, I know what I'm doing.
You'll understand when you're older.
- As a parent, sometimes it's a hope, not a lie.

That turning on the light in the car at night was illegal because it would cause a glare on the windshield.
I believed this into my mid-20s when my husband corrected me with a fuckton of teasing and incredulity.
- I don't know which jurisdiction you're in but, while it isn't illegal in the UK, you're absolutely right about it being a bad idea and you are correct about the reason. In the event of a crash, it could count against you (in the UK, at least).
  
  My dad got pulled over and warned about the light being on. I suspect it was really to check her wasn’t drunk-driving though, as he was giving me a lift me from the pub.

Some that others have already said (hard work = success, trust cops), and off the top of my head:
That my ultimate goal in life is to find a husband, and carry and then raise children (people don't stop saying it once you grow up, you just hopefully learn that they're full of shit)
That "blood is thicker than water" and that your family will always be there for you/want what's best for you
- IIRC, the original "blood is thicker than water" quote is actually "the blood of the covenant is thicker than the water of the womb" which means those that stand by you and fight and struggle with you, and are there for you, are more valuable than those biologically related to you.
  
  Writing in the 1990s and 2000s, author Albert Jack and Messianic Rabbi Richard Pustelniak, claim that the original meaning of the expression was that the ties between people who have made a blood covenant (or have shed blood together in battle) were stronger than ties formed by "the water of the womb", thus "The blood of the covenant is thicker than the water of the womb". Neither of the authors cite any sources to support their claim.
  Nice, do you have a source for that so I can fix the wikipedia article? Either way it doesn't particularly matter.
  
  https://en.wikipedia.org/wiki/Blood_is_thicker_than_water

That you'll be nobody without a degree. Maybe not told directly, but implied in many things that my inferiority-complex-mom said.
- Yeah, I, for example, am a nobody with a degree

I was told they'd always be there for me. Then my dad passed away a few years ago.
I still miss him.
- He's still with you in every lesson, moment, and memory you shared. It's not the same ever again, but it's there.
  
  ❤️
- Half of you is him. He quite literally is right there with you.
- Sounds like he's there with you right now 🤷‍♂️

"maybe" was how my mother said "no."
"Ignore them and they'll go away" in the context of bullying. Hint; it took a mental breakdown and violence to make it stop, back in the mid-90s.
Anything having to do with Christianity.
- Yep, I had a bully in elementary school and my mom tried to work with the system of teachers, principal, admin, etc. for months, and nothing at all was ever done about it.
  Finally when the bullying escalated to physical levels and started to impact my personality outside of school, my parents basically told me that while I might still get in trouble at school, they wouldn't be upset with me at home if I did decide to stand up to the kid. They stressed to me the fine line between standing up for yourself and becoming a bully yourself, and sent me on my way.
  A few days later, my bully found me at lunch and started messing with me. Pushing over my stack of booking, taking some food off my tray...I didn't do anything until he tried to push me out of my seat then it was kind of blurry, but basically I just took a swing at him and knocked him back out of his seat and he hit his head against the wall and started crying.
  I did get in some trouble at school but nothing too bad (especially once Mom was called in and she explained how if they tried to suspend me, she'd put them on blast for how they'd ignored the situation for so long), and that kid was nice as pie to me for the rest of our schooling.
  
  In middle school, I had an incident where a kid a grade above me (he was held back, so he should've been a high schooler by this point and was HUGE) began to mess with me, unprompted, at the end of the day.
  He stepped on my shoes as we walked, poked me, called me names, etc. When I turned around and called him a bitch and kept walking, he sucker punched me and ran. It was so bad I ended up in the emergency room with stitches.
  Anyways, my parents were called and they threatened legal action. The school begged them not to, because they were "going to take care of it, we promise." Once we found out he was only suspended for a week, my parents got all the info they needed to press charges for assault. He ended up in juvie.
  Looking back, it's a shame he ended up "in the system," but that's what he gets for being a bitch. Lol
- “Ignore them and they’ll go away” really is rubbish advice. But that’s of course not to say that the only other step is violence.
  My oldest daughter didn’t have a great time in secondary school (UK, age 11-16) but through persistent discussions and alarm raising to the school, the bullies eventually got the message and left her alone. I’m happy to say she’s having a wonderful time in college now (UK, age 16-18).
  
  Unfortunately that's a minority of cases. Most bullies in my experience, and especially those bullies that are themselves using physical violence, only respond to violence.
  Don't meet violence with violence as your first option. But keep it on the table. It's a viable solution if nothing else works. Some people just don't respond to anything short of getting punched in the mouth, especially kids/teens with their brain chemistry fucked six ways to Sunday by puberty.
- My father pulled that "just ignore it" shit, too. Somehow it wasn't the bully's fault for attacking me, it was my fault for being such an entertaining target.

Grandma adopted a puppy when I was probably 8 or 9. It got parvo. I remember going to her house and asking where the puppy was. She told me that he was sick, so he had to stay outside and I couldn't go outside for the same reason. When I would ask where the puppy is, she would tell me that he's on the side of the house where I couldn't see him. This went on for a long time, I never saw the puppy again and eventually forgot about it entirely.
A decade or two later I found out that my grandma had spent thousands of dollars trying to keep that puppy alive, but parvo took it anyways. She was very upset about it's passing and instead of having me go through it too, she lied to me about it until I completely forgot about it.

God is real.
- Damn didn’t know Lemmy was this much atheist
  
  I mean, it's a bunch of Linux people and communists... dunno what you were expecting.
  
  Hah I had the opposite reaction, I'll surprised how many people there are in this comment section arguing that God is real. I didn't know religious people knew how to use the internet tbh
- The post says a lie, not a truth lol
  
  No, fundie, lol.
  
  God is a 3 letter word created for stupid people to think they have the whole fucking universe wrapped up in a neet little package inside their heads.
  
  😆 🤣 😂

Sitting in a hot tub as a kid will make you infertile.
Totally an old wive's tale. I looked it up when I was an adult and found out I had been deprived of tons of hours of hot tub time.
- the hot tube temperature lowers the current batch of sperm's motility and count, alter the DNA and general quality. your balls cannot extend far enough to escape the hot tub. its not permanent. if you want to conceive, stop boiling your nuts.
  
  Well you assumed my sex, but regardless, that claim is still disputed. Some research indicates that it does temporarily lower sperm counts.
  None of that is particularly relevant though, because my family was claiming it would permanently cause me to become infertile.
- That was them actually believing it, right? Or were they in fact using a deliberate lie to limit your bath tub time for some other reason?
  
  Unclear, my grandma was a nurse. I thought she should have known better, but then again, maybe back in the day that was considered accurate advice medically.

That chocolate milk comes from brown cows.
When I discovered the truth, I learned an important lesson about betrayal.
- Similarly I used to think cows just produced milk for us naturally and we had to milk them or they'd explode when I was a kid. Boy was I in for a shock when I realised what mammals are and that cows need to be pregnant to lactate like any other
  
  Mammals don't need to be pregnant to lactate or, at least, they need to have been pregnant, but, after that, as long as they keep being "milked" they'll continue to lactate. I know you weren't necessarily saying otherwise, but just for clarity.
  I used to work with a guy who genuinely thought all dairy cows were forcibly kept permanently pregnant in order to produce milk.
- Wait, is that why so many adults in the USA believe that? Some childhood prank?
  
  I can only speak to my own experience, but maybe?
  Also, I lied about being American and participated in this thread anyways.
- It does, it just doesn't taste like chocolate.

Almost everything I was taught about nutrition later turned out to be BS
- Yeah this is a great point!
  Fat is bad! Sugar is fine (but brush your teeth)! Yes, this thing that’s been vacuum packed for 24 months is still edible food.
  
  Yes, this thing that’s been vacuum packed for 24 months is still edible food.
  it isn't?

We're all equal.
To borrow from Animal Farm, "We're all equal, but some are more equal than others".
- https://redsails.org/jones-on-animal-farm/
  If you'd like a second opinion on animal farm and Orwell in general.

That people are stupid because they don't have access to knowledge.

That truth is absolute. It's very much subjective. Much in the way right and wrong are subjective.
Life is complicated and things don't fit into perfect little boxes.
- Except when it comes to Math. Math is absolute, as long as you ignore statistics.
  
  as long as you ignore statistics
  See? Conditions
  
  Gotta ignore infinities too. The axioms they're based on are highly controversial.
  
  Nah even statistics is perfectly logical and right, but not because truth is absolute (there may be such a thing, but we definitely don't have access to it in that case. [At this time?]), but rather because math defined there to be a way in which all you derive from it is 'absolutely' true. It just might be 'absolutely' true in a system that isn't ours, or isn't useful for answering anything we want to ask...

The garbagemen did not come back looking for me every week. They just came to pickup the garbage and not to take me away.
Younger Cousin Syndrome...
- My older cousin convinced me the color red is linked to the spirit world. I believed it so much I actually started to see "spirits" when I was a kid.

“It doesn’t matter what they think”
- That is actually true. Let people think what they want
  
  Only true for people that have no power or control over your life.

We don't lick other people.
- I lick my wife. And my previous girlfriends. So some of us actually lick other people.
- Are you saying that we do?
- 😳

My grandma always told me that if you push to hard while pooping your organs will come out. Technically hemorrhoids can do that but they are not really organs.
Microwaves cause cancer.
- Not only hemorrhoids but you can also get diverticula from straining too hard too often. They don't go away once they form, and can become infected (diverticulitis) which is most unpleasant. Pain like kidney stones or appendicitis.
  
  your organs will come out
  Hernia is also a possibility.
  But you have to be pressing really hard and have other problems in connective tissue to have that.
  
  They go away for some but you need to cut out caffeine. ( coffee, chocolate, etc)
- Prolapse is a thing. Good luck googling that.

Nothing good happens after midnight.
- That becomes true again once you turn 40
  
  If you have kids, you'll get a second wind when they're gone. Our adult son was staying with us for a while. We came in about 3:00 a.m. and scared the shit out of him because he thought we were upstairs asleep.
- Followed by "You were conceived at 12:01"
  
  All the best stuff happens after midnight!

That talking to strangers was bad.
- That strangers are bad and cops are good.
  
  That there isn't good and bad of each.

Men are logical. Women are emotional.
Such an enormous generalization and oversimplification. Very false.

It gets better.
- It can. I hope it does for you.
  
  Not always brother

My parents said they would never get divorced.

That the crust is the healthiest part of the bread
- Or the tastiest.
  
  that it is
- It can be good for your teeth.
  
  Or crush them. Depending on hardness.

When I was being taken into surgery they told me we were going into space and gave me gas that they said was to breathe in space. I didn't realize I hadn't actually been to space until I was like eight years old or something like that. Probably older.

Basically everything

Babies get delivered by storks

That a state can't print money
- Why did you hear that as a child? Of course the state prints money, how else would money exist in the first place if no one made the money?
  
  Might be talking about the United States specifically. IIRC the constitution denies individual states the right to mint coin or issue bills of credit, that is a prerogative of the federal government.
  
  It was in the context of limiting public spending. That the state can't just print more money when it runs out of money.

In Catholic school in the nineties and early 2000's, we were all told that the sex abuse scandal was serious but that it was also "a small number of incidents." That we needed to pray for the victims and the souls of the perpetrators.
Then I went to college. Come to find out not only was the child rape widespread, not only did the church actively hide monsters from legal scrutiny, not only was this all directly effecting the local arch diocese (not my school specifically, but church leaders were forced to quickly rename another high school when allegations against a dead bishop proved too numerous to ignore)... not only all that but that it's still going on, just not in first world countries with robust networks of journalists and legal systems. That an alleged pedophile was (while I was in college) living in the Vatican, being directly sheltered from extradition by South American authorities.
I guess the lie was that it was all over. That it was a small problem. That the church was a safe place people could turn to. I left the church at 18 over it, became an atheist by 19, and that's where I'm at now at 35.

Engine ~~breaking~~ braking destroys the engine.
Today: <Bing!> DO NOT ENGAGE CLUTCH ABOVE 1300 RPM.
- Engine breaking destroys the engine.
  Unfortunate typo.

"You're a boy!"
Lol

There's no little tooth bugs crawling back my neck. Toothpaste just isn't healthy to ingest.
- Bahaha, don't swallow tooth paste because of tooth bugs!??!!?! This is the best thing I've ever heard

I love you

I think the opposite list would be shorter

That gender and sexuality and sex is basic make is mean female is girl and heteronormativity.
Fuck all that. I'm free from that bullshit.
- i think 'make is mean' = 'male is men' typo.

That pulling levers in the basement furnace room wouldn't blow the house up. It wasn't until my 20s when it randomly popped into my head and I thought about it with my adult brain and was like "wait... Why would someone install something that would blow the house up?"
- Not as such. But it also doesn't mean that it can't have catastrophic results.
  Your water heater has an overpressure valve, but just one. A failure in that valve and a temperature regulator and you can have your hot water heater shooting up through your roof.
  Your furnace has a control board. It turns the gas on, hits the igniter, watches for flame. An older, shittier designs, it was entirely possible for just one or two sensors to go bad and run the furnace to the point of melting down and have the house burned down. Source: happened to me on vacation many decades ago.