What is it like to be a vampire and/or parent?

Andrew Gelman contemplates a blog post of L.A. Paul and Kieran Healy (based on a preprint of Paul) which asks:  it is possible to make rational decisions about whether to have children?

Paul and Healy’s argument is that, given the widely accepted claim that childbearing is a transformational event whose nature it’s impossible to convey to those who haven’t done it, it may be impossible for people to use the usual “what would it be like to to X?” method of deciding whether to have a kid.

Gelman says:

…even though you can’t know how it will feel after you have the baby, you can generalize from others’ experiences. People are similar to each other in many ways, and you can learn a lot about future outcomes by observing older people (or by reading research such as that popularized by Kahneman, regarding predicted vs. actual future happiness). Thus, I think it’s perfectly rational to aim to have (or not have) a child, with the decision a more-or-less rational calculation based on extrapolation from the experiences of older people, similar to oneself, who’ve faced the same decision earlier in their lives.

Here’s how I’d defend Paul and Healy from this objection.

Suppose you had a lot of friends who’d been bitten by vampires and transformed into immortal soulless monsters.  And when you meet up with these guys they’re always going on and on about how awesome it is being a vampire:  “I’m totally glad I became undead, I’d never go back to being human, are you kidding me?  Now I’m superstrong, I’m immortal, I have this great group of vampires I run with, I feel like I really know what it’s all about now in a way I didn’t get before.  Life has meaning, life has purpose.  I can’t really explain it, you just gotta do it.”  And you know, you sort of wish they’d be a little less rah-rah about it, like, do you have to post a picture on Facebook of every person you kill and eat?  You’re a vampire, that’s what you do, I get it!  But at the same time you can’t help starting to wonder whether they’re on to something.

AND YET:

I don’t think it’s actually good decision-making to say:  people similar to me became vampires and prefer that to their former lives as humans, so I should become a vampire too.  Because the vampire is not the same being as the human who used to occupy that body.  Who cares whether vampires like being vampires better than they like being human?  What matters is what I prefer, not what the vampiric version of me would prefer.  And I, a human, prefer not to be a vampire.

As for me, I’m a parent, and I don’t think that my identity underwent a radical transformation.  I’m the same person I was, but with two kids.   So when I tell friends it’s my experience that having kids is pretty worthwhile, I’m not saying that from across an unbridgable perceptual divide — I’m saying that I am still similar to you, and I like having kids, so you might too.  Paul and Healy’s argument doesn’t refer to my case at all:  they’re just saying that if parents are about as different from non-parents as vampires are from humans, then there’s a real difficulty in deciding whether to have children based on parents’ testimonies, however sincere.

(Remark:  Invasion of the Body Snatchers is sort of about the question Paul and Healy raise.  Many have understood the original movie as referring to Communism, but it might be interesting to go back and watch it as a movie about childbearing.  It is, after all, about gross slimy little creatures that grow in the dark and sustain themselves on your body.  And then the new being known as “you” goes around trying to convince others that the experience is really worth it!)

Update:  Kieran points out that the reference to “body-snatching” is already present in their original post — I must have read this, forgotten it, then thought I’d come up with it as an apposite example myself….