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Doubt, Science, and Magical Creatures - a Child's Perspective

33 Post author: Benquo 28 December 2013 03:26PM


I grew up in a Jewish household, so I didn't have Santa Claus to doubt - but I did have the tooth fairy.

It was hard for me to believe that a magical being I had never seen somehow knew whenever any child lost their tooth, snuck into their house unobserved without setting off the alarms, for unknown reasons took the tooth, and for even less fathomable reasons left a dollar and a note in my mom's handwriting.

On the other hand, the alternative hypothesis was no less disturbing: my parents were lying to me.

Of course I had to know which of these terrible things was true. So one night, when my parents were out (though I was still young enough to have a babysitter), I noticed that my tooth was coming out and decided that this would be...

A Perfect Opportunity for an Experiment.

I reasoned that if my parents didn't know about the tooth, they wouldn't be able to fake a tooth fairy appearance. I would find a dollar and note under my pillow if, but only if, the tooth fairy were real.

I solemnly told the babysitter, "I lost my tooth, but don't tell Mom and Dad. It's important - it's science!" Then at the end of the night I went to my bedroom, put the tooth under the pillow, and went to sleep. The next morning, I woke up and looked under my pillow. The tooth was gone, and in place there was a dollar and a note from the "tooth fairy."

This could have been the end of the story. I could have decided that I'd performed an experiment that would come out one way if the tooth fairy were real, and a different way if the tooth fairy were not. But I was more skeptical than that. I thought, "What's more likely? That a magical creature took my tooth? Or that the babysitter told my parents?"

I was furious at the possibility of such an egregious violation of experimental protocol, and never trusted that babysitter in the lab again.

An Improvement in Experimental Design

The next time, I was more careful. I understood that the flaw in the previous experiment had been failure to adequately conceal the information from my parents. So the next time I lost a tooth, I told no one. As soon as I felt it coming loose in my mouth, I ducked into the bathroom, ran it under the tap to clean it, wrapped it in a tissue, stuck it in my pocket, and went about my day as if nothing had happened. That night, when no one was around to see, I put the tooth under my pillow before I went to sleep.

In the morning, I looked under the pillow. No note. No dollar. Just that tooth. I grabbed the incriminating evidence and burst into my parents bedroom, demanding to know:

"If, as you say, there is a tooth fairy, then how do you explain THIS?!"

What can we learn from this?

The basic idea of the experiment was ideal. It was testing a binary hypothesis, and was expected to perfectly distinguish between the two possibilities. However, if I had known then what I know now about rationality, I could have done better.

As soon as my first experiment produced an unexpected positive result, just by learning that fact, I knew why it had happened, and what I needed to fix in the experiment to produce strong evidence. Prior to the first experiment would have been a perfect opportunity to apply the "Internal Simulator," as CFAR calls it - imagining in advance getting each of the two possible results, and what I think afterwards - do I think the experiment worked? Do I wish I'd done something differently? - in order to give myself the opportunity to correct those errors in advance instead of performing a costly experiment (I had a limited number of baby teeth!) to find them.


Cross-posted at my personal blog.

Comments (53)

Comment author: ygert 28 December 2013 08:55:04PM *  13 points [-]

That's a good rationalist success story. You remind me of my own story with the tooth fairy: I will not relate it in detail here, as it is similar to yours, just less dramatic. At a certain point, I doubted the existence of the tooth fairy, so the next time a tooth fell out I put it under my pillow without telling anyone, and it was still there the next day. I confronted my parents, and they readily admitted the non-existence of the tooth fairy.

In fact, it went off as a perfect experiment, which kind of ruins its value as a story, at least when compared with yours. I did an experiment, got a result, and that was that. The one thing I'm still kind of bitter about is my parents' first reaction to my confrontation of them: Rather than praising me on my discovery and correct use of the scientific method, their reaction was along the lines of "If you suspected, why didn't you just tell us? We would have just admitted it. There was no need for that test to find proof to confront us with."

Comment author: Benquo 28 December 2013 09:28:43PM *  9 points [-]

Well, I will praise you for your discovery and correct use of the scientific method:

Good job independently discovering the scientific method, and using it correctly! Also congratulations on acquiring a true opinion and becoming less wrong.

Comment author: Heka 28 December 2013 11:22:39PM 5 points [-]

Too bad you didn't get positive feedback. The awaited praise for discoveries keeps scientists going. In terms of money the smart decision would have been to hide the results from parents to keep the dollars flowing in.

Comment author: ygert 29 December 2013 11:10:59AM 7 points [-]

Oh, but the money did keep on flowing in! My parents may not have handled the situation perfectly, but they most certainly didn't cut off the money just because I uncovered their lies. To do so would be punishing me for finding out, which was certainly not their intention.

After that point, whenever a tooth fell out, I'd just hand it to my mother and she would dig out the cash for me, without the whole ritual of putting the tooth under the pillow and having it be replaced by an imaginary being who collects teeth for some reason.

Comment author: TobyBartels 02 January 2014 12:14:12AM 0 points [-]

Nice, but it seems rather less satisfying not to even put it under the pillow. This leads to a larger point: you don't have to give up the rituals of religion when you give up the doctrine!

Comment author: ygert 02 January 2014 10:29:43AM 0 points [-]

Sorry, but I disagree. Personally, I rather dislike going through arbitrary pointless motions. The "magic" is already gone, and mindlessly trying to go through the same motions to bring it back is futile. We are better off without it.

Comment author: TobyBartels 03 January 2014 01:06:42AM 3 points [-]

If that's what you prefer, then of course you did the right thing.

Comment author: AndHisHorse 02 January 2014 12:21:35PM 1 point [-]

The magic may be gone, but I believe that Toby's point was that even if the personal power of the ritual is revealed to be nonexistent, the social power may still remain.

Comment author: ygert 02 January 2014 02:49:42PM *  1 point [-]

I don't understand: could you explain what specifically you are claiming remains? Social power implies that it impacts other people and their actions, which I don't think is the case in this situation.

Comment author: dougclow 29 December 2013 06:14:41AM 11 points [-]

... and this is part of why my kids have always known that Santa and the Tooth Fairy are fun pretend games we play, not real. I really don't see what they're "missing out": they seem no less excited about Santa coming than other kids, and get no fewer presents.

Not lying about it has all sorts of extra benefits. It makes keeping the story straight easy. It means I'm not dreading that awkward moment when they've half-guessed the truth and ask about it outright. And I wasn't remotely tempted to tell them -as several people I know did - that the International Space Station pass on Christmas Eve was Santa on a warm-up run. Firstly, because that would mean you couldn't tell them about the ISS and how you can see it with your own eyes if you look up at the right time, and that's really cool. And secondly, because they'd have recognised it anyway.

It's also helpful social practice in behaving with integrity but respectfully when around people who passionately defend their supernatural beliefs.

Comment author: fowlertm 28 December 2013 03:50:12PM 11 points [-]

It's also possible that, in concealing the information from your parents, you also managed to conceal it from the TF as well. It would be much, much harder to figure that out experimentally, given how little we know about the mechanisms by which purportedly magical beings interact with information.

Comment author: Benquo 28 December 2013 03:56:40PM 5 points [-]

True but my prior on that was about an order of magnitude lower than my prior on the tooth fairy being real at all. It's not necessary to explain the phenomena if it gets the info via parents.

Comment author: TobyBartels 02 January 2014 12:12:35AM 0 points [-]

In my household, it's well established that Santa Claus is in regular contact with the parents; Tooth Fairy lore is less well established, but that makes this a reasonable hypothesis. In yours, maybe not.

Comment author: ChristianKl 29 December 2013 09:12:04PM 3 points [-]

The straightforward way would be to simply ask the parents how the tooth fairy knows about the teeth before running the experiment.

Comment author: ygert 29 December 2013 09:26:43PM *  1 point [-]

The answer to that is "But maybe the parents are misinformed about the tooth fairies' abilities?" You can go on and on like this, but at this point I would stop praisuing the child for pursuing the ratinal method for solving problems, and strat educatting the child in the next lesson of rationality: 0 and 1 are not probabilities, all knowledge is probibalistic, and you need to do VoI calculations before rushing off to try to rule out narrow and increasingly unlikly options.

Comment author: Vulture 28 December 2013 06:58:46PM 2 points [-]

But the hypothesis where the TF's knowledge is more closely linked to the parents' is less natural; to me it feels like making excuses for a bad hypothesis.

Comment author: JoshuaZ 28 December 2013 08:24:18PM *  1 point [-]

Does it? Suppose for example that that the Tooth Fairy has every house with little children bugged and so hears verbal statements about loose teeth.

Comment author: polymathwannabe 29 December 2013 05:36:10PM 1 point [-]

That would require monitoring what happens to loose teeth in deaf families

Comment author: Vaniver 29 December 2013 06:55:30PM 3 points [-]

But the Tooth Fairy probably knows how to read lips, given its fixation with teeth.

Comment author: polymathwannabe 29 December 2013 08:17:32PM 2 points [-]

That leads me to think of some ethically questionable testing scenarios.

Comment author: ygert 29 December 2013 09:19:34PM 2 points [-]


But seriously, there are simpler tests to do, or to do first. Try telling your parents not out loud, but in a written note. That would rule out audio bugging. Try telling an empty room, when no one else is around. That could rule out your parents. Try telling someone you know won't understand you. (Like a younger sibling.) Try miming it to your parents without using words. Try falsely telling your parents that a tooth fell out, when none did. Try telling your parents about your tooth that fell out, but not putting it under your pillow that night. Try giving your fallen-out tooth to a younger sibling and tricking him into pretending that that tooth was his to your parents. (Although that would probably mean giving up the income from that tooth.)

All in all, there are a lot of possible open tests that could be done, to narrow down the search space dramatically.

Comment author: NancyLebovitz 30 December 2013 01:24:44AM 7 points [-]

You have a limited number of teeth to experiment with.

Comment author: Lethalmud 07 January 2014 01:31:49PM 3 points [-]

That's where your little brother comes in.

Comment author: Vulture 29 December 2013 02:59:57AM *  1 point [-]

But the point is that if we allow the Tooth Fairy to be sufficiently ill-defined, we can construct a version of it that allows for any negative experimental result. Benquo had a preconceived model of the "the Tooth Fairy" which was given some initial weight, and when it was contradicted by an experimental result then Occam's Razor strongly insists that we fall back on the null hypothesis*.

*(Unless there was some pre-existing good reason to suspect the "bugged house" hypothesis, which I doubt there was)

Comment author: Grif 28 December 2013 09:45:21PM *  1 point [-]

Perhaps the tooth fairy doesn't magically sense baby teeth under pillows, but she has to be sent a telepathic note from the child's parents first.

Comment author: James_Miller 28 December 2013 05:36:53PM 8 points [-]

A few months after Christmas I was checking my Amazon account of past orders when my son happened to be looking at my computer and he saw a present I had previously claimed was from Santa. He took this as evidence for Santa's non-existence.

Comment author: polymathwannabe 29 December 2013 05:41:09PM 5 points [-]

This raises the question of why you made your child believe in Santa Claus in the first place.

Comment author: James_Miller 29 December 2013 05:49:19PM 3 points [-]

It made his life more interesting, and helped him socialize with classmates who believed in Santa.

Comment author: scav 07 January 2014 11:56:10AM 5 points [-]

I'm not going to criticise your decision, especially with regard to the social situation at school, which I can't speculate about. But I doubt it's more interesting to believe in the weird collection of junk memes that Santa Claus has become.

Maybe it's just me, but I think the truth is always more interesting, because there's aways more detail in it. Fake things are ultimately very boring; you poke at them a bit and there's nothing there. Flying reindeer are just pictures of approximately deer-like animals (usually more like red deer) positioned above the ground. Real reindeer are pretty amazing.

Comment author: byrnema 03 January 2014 06:55:26PM *  7 points [-]

There is a website that tells children if they are on the 'naughty or nice' list that my brother-in-law showed the children over Christmas. Now a couple weeks after Christmas, when all children should be much less concerned about whether they are on the nice list, my six year old comes running in the kitchen demanding that we check her status on the website.

It was pretty clear from her manner that she hopes to systematically test whether different activities are "wrong-wrong" (from the point of view of high-status Santa) or just wrong because we think so. While I admire her desire to use experiments to identify the limits of good behavior, it is of course not a well-defined experiment and I'm not sure how to immediately discourage her...a solution just occurred to me to tell her that the webpage is "not working" after Christmas. (Along the lines of, 'the best painkiller that I have'.)

Comment author: TobyBartels 06 January 2014 02:48:42PM 3 points [-]

If you show them apparently arbitrary short-term responses to specific actions, but a long-run trend that follows their behaviour, then you can explain that it takes a while for their actions to be reflected on Santa's list; thereby preparing them for a lifetime of dealing with their credit rating.

Comment author: Swimmer963 29 December 2013 06:02:06AM 6 points [-]

I don't remember ever actually believing in the tooth fairy (or Santa Clause). I also don't remember ever having a problem with the world in which parents told their kids that fictional beings existed and would give them money or presents; it seemed so obvious, and harmless. I was happy to put my tooth under the pillow and get money–it was a soothing ritual. I remember thinking it was freaking obvious that Santa Clause was my parents, but putting out cookies for "Santa Clause" was sort of a fun family ritual anyway.

I wonder what makes the difference between a child who has my outlook, and a child who is disturbed by the fact that either magical beings exist or their parents are lying.

Comment author: ialdabaoth 29 December 2013 06:40:12AM 4 points [-]

I wonder what makes the difference between a child who has my outlook, and a child who is disturbed by the fact that either magical beings exist or their parents are lying.

Trust / security in the child-parent bond.

Comment author: NancyLebovitz 29 December 2013 03:01:07PM 5 points [-]

I think trust is in play, but there's also a matter of how literally people take language. Some people are much more literal about language than others, This might be an independent personality factor, or it might be a matter of lack of trust in one's ability to understand body language, tone of voice, etc.

Comment author: Benquo 29 December 2013 05:12:14PM 2 points [-]

Anecdatum: I was pretty literal, and pretty terrible at understanding nonverbal communication.

Comment author: latanius 28 December 2013 05:48:56PM 5 points [-]

... I did my fair share too, Santa vs. thin threads spun across the way between where the presents were supposed to emerge and the door... "stand back, I'm going to try Science" for the first time I remember.

Actually, it was a really nice experience not only about Science but also about how compartmentalization feels from the inside. I definitely remember thinking both that it's my parents and that it's some kind of mystical thingy, the only new thing that year was that these two aren't supposed to coexist in the same world. Not surprisingly, it's the very same feeling that I felt after being exposed to a semester of catholic middle school. Didn't have a name for it then though...

Comment author: Prismattic 29 December 2013 04:51:26AM 19 points [-]

Ladies and gentlemen, I present the difference between instrumental and epistemic rationality:

Epistemic rationalist -- The tooth fairy is not real. I must do my part to make this common knowledge.

Instrumental rationalist -- If I allow this polite fiction to continue, I keep getting a dollar every time I lose a tooth.

Comment author: Eliezer_Yudkowsky 30 December 2013 12:49:28AM 19 points [-]

Rational parents: After our child figures out the truth, we'll increase the benefits to $1.50.

Comment author: MrMind 07 January 2014 05:13:36PM 2 points [-]

That's what I plan to do if I ever have any children.

Comment author: HalMorris 30 December 2013 01:35:39AM 14 points [-]

Or put another way, An Englishman, a Frenchman, and a Bell Labs Engineer (this was told around Bell Labs) were in some French African colony -- probably wherever Camus' The Stranger took place, and were rounded up by the police on some mistaken charges, tried, and found guilty. The Englishman was led to the guillotine, and, asked if he had any last words, said "God Save the Queen (or King, whichever)". The guillotine was released, but did not drop, and mysteriously hung there. The crowd shouted "It's a miracle, it's a miracle, you must release this man!", and the officials looked at each other, and agreed to release him. The Frenchman was led to the guillotine, and, asked if he had any last words, said "Liberty, Equality and Fraternity!". The guillotine was released, but did not drop, and mysteriously hung there. The crowd shouted "It's a miracle, it's a miracle, you must release this man!", and the officials looked at each other, and agreed to release him. The Bell Labs Engineer was led to the guillotine, and, asked if he had any last words, said "I think I see what's making it stick like that."

Comment author: Watercressed 29 December 2013 06:18:26PM 5 points [-]

Since when did epistemic rationality demand making the truth common knowledge? It just means you should know what's true yourself.

Comment author: Vaniver 29 December 2013 06:42:53PM 3 points [-]

It seems fair to consider epistemic hygiene part of epistemic rationality.

Comment author: polymathwannabe 29 December 2013 05:35:11PM 3 points [-]

Your choice will depend on whether the vindication of truth is worth more or less than a finite and unsteady flow of one-dollar notes to you.

Comment author: shminux 29 December 2013 08:15:28AM 9 points [-]

I wonder if there is a smarter child who, after figuring out the truth, announces the fallen tooth the next night, just to continue getting paid. After all, some truths are best concealed from the world.

Comment author: Wes_W 29 December 2013 09:38:36AM 24 points [-]

In my family, there is a story about my great-aunt when she was a child, involving a game where she was allowed to choose between a nickel and a dime. She took the nickel instead of the dime, and all the grown-ups got a chuckle at her cute naivete. This continued long past the age when she should have known the smaller dime was nevertheless more valuable, and eventually her mother realized she was well aware that, if she took the dime even once, people would stop inviting her to play that game.

It's not a tooth-fairy story specifically, but yes, there certainly are children that clever.

Comment author: NancyLebovitz 29 December 2013 03:02:12PM 10 points [-]

I've heard that story as a joke. This is the first time I've heard it attached to a particular person.

Comment author: [deleted] 30 December 2013 11:41:24AM *  1 point [-]

if she took the dime even once, people would stop inviting her to play that game.

And that would be a bad thing why? Did she enjoy being chuckled at?

Comment author: Wes_W 30 December 2013 05:16:51PM 9 points [-]

Probably not, but she did enjoy extra spending money. Remember that this story (ostensibly, although see NancyLebovitz's comment) takes place long enough ago that a nickel could actually buy something.

If I were to assign a moral to the story, it would be something like "don't assume children aren't extremely clever". The girl not only understood the game on the object level, but also grasped the metagame and turned it to her advantage.

(The meta-moral for myself would be "remember that some of your relatives are senile enough to misremember jokes as autobiographical".)

Comment author: ygert 30 December 2013 11:52:13AM *  8 points [-]

I think the point is that she enjoyed getting free money more than she disliked being chuckled at, so she was willing to suffer being chuckled at in order to receive the free money.

Comment author: William_Quixote 30 December 2013 11:59:09AM 5 points [-]

People often do like making their relatives happy. If her family was laughing and having a good time it doesn't seem that strange for her to just play along.

I also wouldn't be shocked either if her family knew to some extent that she was playing along and that it was something of a family "in joke". (not the explicit kind of in joke, just an organic kind)

Comment author: Gunnar_Zarncke 28 December 2013 09:46:28PM 2 points [-]

I wonder what your parents replied and whether that restored your trust in them. I'd guess that you learned that they can be trusted - except on certain topics.

A corollary might be that compartmentalization (c18n?) is passed on from parents to children (partly indirectly by parents choosing institutions which also promote this).

Comment author: Sanji 29 December 2013 02:42:53PM 1 point [-]

I had the same experience with Santa, but instead of trying a super complicated experiment, I just tried to stay up past midnight. Little did I know that Santa had some sort of sleep dust (or I had never stayed up past 10 so I fell asleep naturally)

Comment author: [deleted] 29 December 2013 11:52:48AM 1 point [-]

Ha, this reminds me of a similar attempt with Santa. I can’t remember how old I was but I was probably right on the cusp of knowing the Santa idea was false, and I think some of my pals were already saying this. So my idea was: we leave carrots out for the reindeers, so all you need to do is count the ones in the cupboard on Xmas Eve, then count them after to see if they had been replaced or eaten. I thought this was quite a good experiment so told some of my pals, and they all said no, Santa doesn’t exist, and I remember being quite annoyed that they were ignoring what I thought was quite an elegant experiment, regardless of what they already knew about Santa.

I didn’t carry it out myself but I’ve a vague memory of trying and being foiled, probably because my parents had either overheard me or didn’t let me run around the kitchen on my own at that age.