Long story short: amongst all the common value systems, only if you are anti-natalist, should you have a 50-50 (or worse) custody regime in divorce, as contrasted with the mother getting full custody and paying all child support. (There are special cases where you can set it so the father is the 100-0 in the split, but since the mother ultimately controls childbearing in any free society, it is her moral hazard and therefore that is the default position).
I think the easiest argument is by cases; one for each posture of people who want kids, starting from the male perspective, since any female can have kids whenever she wants, and my particular point of focus is how to have happy families (and that typically requires a mother and father). Also remember that I use sex in the proper meaning as barebacking, and not in the macro stupidity of condoms.
In the case of 50-50 custody:
- If a typical male doesn’t want children, his only options are to make himself infertile via vasectomy, or to find a woman he absolutely can trust.
- If a male isn’t sure, he’s not going to have a sexual relationship with any fertile woman that he doesn’t absolutely trust.
- If a male is sure he wants kids, he still has to find a woman he absolutely trusts, because she can take the kids from him at any point and leave him with a massive bill and split custody.
In other words, to have any kind of sexual relationship with a fertile woman, the male either gets a vasectomy, or his partner has to be trustworthy and she also has to have compatible goals. Being specific: an essentially perfect marriage with a woman who is perfect for him, is the only acceptable risk option for a man who wants kids.
In the case of 100-0 custody (and no non-custody child support):
- If the male doesn’t want children, he only has to be concerned about the woman having more VD, cheating on him, etc.
- If the male isn’t sure, he has the option either to go with a single mother, or with a woman who isn’t sure she wants kids, or with a woman who is sure she wants kids and really loves him/thinks he would be great, and can’t find a better man who is sure he wants kids. (That is, the woman who wants kids is gambling and hoping he turns, which sometimes he will)
- If the male is sure, he also has the option of the single mothers, divorcees, etc. because he doesn’t have to be so concerned about the disfavourable (~70% with single mothers) odds associated with the dissolution of the relationship.
To summarize, if the man only has to care if his woman loves him, he can take a flyer on a lot more relationships. That means in aggregate, there will be a lot more fathers, more children, and more chances for people to get into happy relationships, instead of one and done until the woman is in her mid-40s.
Taking the matter from the female perspective, within a relationship (since she gatekeeps both sex and children, she can do whatever she wants) in 50-50:
- If the male (or female) wants out of the relationship/is abusive/etc., this is typically bad for her because she has to continue to deal with the male, and she has to have a job. Other than staying in an abusive relationship, it’s the worst of all possible situations for her.
- If the male isn’t that attached to the relationship, and therefore can be swayed to stay, the woman gets extra leverage over him via the 50-50 split. This means she can give him less sex and love and still keep him; it puts her into a better negotiating position in the relationship generally.
In the 100-0 female relationship:
- She can kick the father to the curb whenever he acts up, and as long as she can find a job, another lover, etc. she doesn’t have to deal with the father anymore. That’s a big win for her in any difficult relationship situation.
- If the male isn’t that attached to the relationship, he’s significantly more likely to leave, since the woman’s only leverage is via seeing the children, and she is a mother whose body is wrecked. She has to court the male constantly to keep him attached.
In summary, for the woman (and by similar reasoning, the man), the 100-0 custody arrangement is vastly superior for bad situations, but potentially significantly worse for iffy but manageable relationships. In the typical struggling relationship situation, as the woman has the advantage in relationships over the man, it makes the male’s relationships worse when the woman is unattached, but better if she believes in the relationship.
We also should note that the male doesn’t get the option to parent his kids in the 100-0 custody regime; so if he really wants to be a great father, he can be left out in the cold at any time. Hence, there are special cases where you could assign 100 percent custody to a reasonably well-off father, as he could assume the full responsibility for kids when the woman really wants the relationship but isn’t 100% sure about kids.
We also should consider the situation of relationship patterns that are not following wise practices: that is, promiscuity. In a 50-50 split, a man can’t have sex in a promiscuous way with any fertile woman, as the costs are too high. He either is going to see older women who can’t support any childbearing agenda (therefore anti-natalist) or go see prostitutes and the rampant VD will spread, or he has to have a vasectomy.
For the promiscuous, or even not so promiscuous woman, the 50-50 situation is even more dire. Following through with the correct decisions, an unmarried young or middle-aged woman likely never will have sex with any young or middle aged male who isn’t rich, until and unless they commit to what essentially amounts to a marriage-like relationship, which is the opposite of the promiscuous value system.
We also have to consider the situation of poverty births, where the mother (or possibly even father in a surrogate situation) shows up at the hospital with a belly and now we have bills to pay. Unless you have a very pro-natalist value system, it is not for the state to subsidize other people’s children. So, who should get the bill, and by what proceeding will this be determined? People say “oh genetic screen and you know the father” but that’s not all there is to it. What happens if the woman lies about her desire to have children? This is not at all an uncommon case, that a woman decides to conceive and simply doesn’t involve the father. He may not even realize or know she conceived. If the father then asserts that she lied, now here are your possible responses:
- You go to court and try to figure out if the guy agreed (dicey, and highly unlikely to prove beyond a reasonable doubt, therefore practically a 100-0 custody arrangement)
- You ignore the male’s protests and award him 50% custody and child support
It is this later case that creates danger for the woman: before she even gives birth, if the man finds out she’s pregnant and therefore is about to ruin his life, he has an obvious incentive to abuse her to get an abortion. He has an even more obvious incentive to beat her belly and cause a miscarriage. He also maintains his incentive after the birth, either to kill the mother, baby, or both (e.g. Emmanuel Coble**). It’s true that in many anti-natalist value systems, somehow killing the baby would be an acceptable outcome. However, the way in which this is managed is decidedly suboptimal. If you are comfortable with the male killing his child, you may as well just give him the option at the hospital, or force the abortion, etc. instead of getting the woman beaten or killed too. If you really just care that these people are promiscuous, it would be way better to throw them in prison and strip them of custody from the get-go and not have a poorly raised child be the collateral damage. So the 50-50 regime isn’t the way you want to pursue these policies.
In overall summary, the 50-50 regime only could be superior for situations where one relationship partner is marginally attached and the other one wants to continue the relationship. In almost every other common case and value system, 100-0 custody for the mother as the default, with special cases for responsible men, obviously is superior.
** Note: at the time I write this (September 2022), he has not been convicted of anything, so although the police report is rather damning, we should remember that he is innocent until proven guilty.