I mean as a side-note, I have in fact found overall that reassuring kids young enough to be scared of "illogical" things that either they or you, the adult tasked with their care, are totally capable of handling/beating up/dispersing the Scary Thing is vastly more effective than trying either to convince them that the scary thing doesn't exist, or to convince them that the scary thing isn't scary.
I nannied for a three year old who overnight became deeply scared of owls. We're not sure why. We're not sure she'd even ever seen a real owl. The "owls" that she described did not seem to be based on real birds. Her parents and grandmother, very diligent and reasonable people, spent a week trying to convince her that owls weren't scary and there were no owls in the house because that's not what owls did.
On the first round of "no but if I go to bed there will be owls" I calmly informed her that there were not and never would be any owls in this house because I was there and the owls were afraid of me. And not only were the owls afraid of me when I was there, but I also had the ability to make secret signs that the bad owls would see to let them know that I came to this house every day and if I found bad owls anywhere near here they were In Trouble. So she didn't need to worry about any owls.
She turned this over for a few minutes and then we went and she had nap time.
(She did come back a few days later to say but I meant magic owls, and I said I know, I was also talking about the magic owls, obviously as you have since learned from the Kratt brothers, real owls are just kind of silly birds that puke up mice pellets. She remained satisfied.)
Over the next little while she would occasionally reassert what I had told her about owls being scared of me, and at one point she also added the extra detail that while I could beat up the owls[subtext: magic monsters], she would beat up the bees[again subtext: magic monsters, not the real bees]. I agreed that this was likely so.
A year later she informed me that she had been very silly when she was "little" and scared of owls, but owls were just birds.
I've had similar experiences with other kids and other "irrational" fears and in the end I believe what it comes down to is that when you are Smol, the world is fuckin' scary, and what is really important and really valuable is knowing that when Something Scary Happens, the grownup who is your caregiver will deal with it. That they understand that it is scary - they're not ignoring the danger and thus making it more dangerous, they're not trying to convince you that the danger doesn't exist[1] and so putting you in this place where you don't know whether to trust your own intuitions, all the rest of those things. They're just confirming: if there are Bad Owls, that's still not a problem, because I know how to deal with Bad Owls.
Now obviously yes you also watch nature documentaries or go to the stand with the raptor education stuff with them or whatever else so that they get an idea of what real owls actually are; or in other cases you can ask curious questions about the rest of the fear of, I dunno, under the bed, and see if there's actually something that can be done about it (maybe there's a weird echo in their room that makes it sound like noise is coming from under the bed - you'd be amazed).
But to start with, you go: the monster under the bed isn't a problem, because I am much stronger than the monster under the bed, and I am better at magic, and I have dealt with it.
If you can add, apropos of the post, useful real world details like this one - "not only that did you know that a skeleton would be very weak, because it is just bones and doesn't have any muscles, so because I have muscles I can smash it to bits" - or whatever, that's even better!
This is also actually a very similar process to how CBT is supposed to work for actual reasonable fears that are nevertheless out of proportion or otherwise fucking you over and making you unable to function (because there is literally no bad situation that is not made worse by anxiety attacks, frozen cognition, brain-skips, memory fog, and other distortions of disordered anxiety): okay fine, even if thing is real, what is in your power to do about it, what steps can you actually take, and where do you go with them from here, even if they are small and not overwhelming/going to fix everything, because no matter what the problem is, being frozen in terror of it is always going to be the least useful or effective option. (Even if you do decide you're totally helpless then you might as well go do something fun, because your angst isn't helping either, you know?)
Just altered for Smol Child Brains, and the fact that the most important thing for a Smol Child Brain is to know that whatever happens, your grownup will deal with it.[2]
[1] like yes, the danger doesn't exist, but these are Small Children and the world is very big and complicated and it might exist and it feels emotionally logical for it to exist so even if it really doesn't, it still feels pretty gaslighty when the grownups tell you that it doesn't but you're still sitting there Feeling Afraid about it.
[2] "but what if it's not guaranteed that I deal with it": look, if you DO actually Lose against the universe, there is nothing the small child can do about it either. If you eventually collapse and fail the small child, yes, that will fuck them over. But it will not actually fuck them over worse, at this point in their brain development, to have believed in you without question up to that point and believed you could fight god in the town centre and win, before they find out you couldn't. Just a weird fact of child development.
