> Telling someone that wants to have a kid that they shouldn't is much less effective than explaining someone why they should to vegan most of the week.

Sure, but that's a very black-and-white take.

Firstly, those things aren't in opposition; it's trivial to advocate both.

Secondly, "telling someone that wants to have a kid that they shouldn't" is picking a losing battle. In many (most? all?) societies having children is effectively the default: choosing not to have kids is an explicit opt-out, that many people might not even consider. Lots of activities can help tip the scales a little, in a much more effective way, such as:

- Challenging everyday assumptions that everyone wants kids (e.g. if asked "when are you planning to have kids", pointing out that the "when" is presumptuous; or if asked "do you want a boy or a girl", what about "neither"; etc.)

- Sticking up for those who don't have/want kids, if getting pressured e.g. by their family (I get this a lot)

- Normalising childlessness in media by having more characters who just-so-happen to not want kids (often it's only ever mentioned in order to set up those characters to later either have kids, or express regret at not doing so; e.g. the Wilsons in the US Dennis the Menace come to mind)

- Promoting adoption and fostering, including possible changes to the rules. I've had many conversations where adoption is dismissed due to the difficulty of the process, which I can imagine is pushed more by the risk of (hopefully) rare abuses than by the reality of (unfortunately) common day-to-day struggles.

- Rebalancing the economics, to financially disincentivise having children (and certainly to avoid children being an income stream for prospective parents). Possibly have more existing support going directly to the children, e.g. via school-provided facilities, rather than as cash to parents.

- Increasing availability of contraception, and removal of associated myths/taboos (Thailand seems to be a good example here https://www.who.int/bulletin/volumes/88/6/10-010610/en ). Ideally reproduction would be opt-in (as with IUDs, for example): creating a human life is too important to happen "accidentally". Research and development of a male equivalent to the contraceptive pill would also be very important.

- Removing taboos around vasectomies and sterilisation. I've heard many stories of doctors refusing to carry out these procedures, or making patients jump through extraneous hoops to get it done (e.g. it's brought up a lot on https://www.reddit.com/r/childfree ). Here's another Thai example https://www.upi.com/Archives/1983/12/06/Thailand-gives-free-...

- Encouraging closer-knit communities. Whilst technology like social media has made it easier to find and communicate with like-minded individuals, it also makes it easier to avoid human contact with those around us. For many, child-rearing instincts might be satisfied by helping to raise children who don't happen to share their genes. Perhaps technology could help with this, e.g. for organisation at a local level.

These are things off the top of my head. "Telling someone that wants to have a kid that they shouldn't" is a woefully simplistic dismissal.