it's not obvious to me that children are a good investment

I think you're engaging in nirvana fallacy. Children are not a good investment compared to what?

Again -- let's take a medieval European peasant. He has no ability to accumulate capital because he's poor, because his lord will just take his money if he notices it, and because once in a while an army passes through and basically grabs everything that isn't nailed down. He doesn't have any apprentices because peasants don't have apprentices (and apprentices leave once they learn the craft, anyway). He certainly has friends, but even his friends will feed their family before him when the next famine comes. So, what kind of investments into a non-starving old age should he make?

He can buy jars of salt and bury them. His children, if they survive, may feed their own children rather than him in the next famine. A network of friends and a high standing in the community are at least as valuable to him as investing resources in birthing and raising children who probably won't see adulthood. He can become an active and respected member of the church. The church is probably a better bet overall since there's a decent chance his own kids will die, but the church will probably survive.

I'm not an expert on 14th century investment opportunities, I just find the idea that children are clearly the best selfish investment incredible. If children are such a good investment, why did we need a modest proposal? And why are the rich, who retirements are not in doubt, so desirous of children? Why does king Priam need 50 sons? He's the king of a city. What fears does he have about retirement?

I don't know that we have access to facts. Everything is interpreted. Everything is a model.

OK. There were 3,932,181 births in the US in 2013 giving the birth rate of 12.4 / 1000 population (source). Tell me what kind of model is that, which theory does this piece of information critically depends on.

The ones digit of that number is almost certainly wrong and I'm not particularly confident about the next two. Believing that number relies on an enormous number of assumptions about the bureaucracy that generated it. Now my model of the world tells me that the bureaucratic system that calculates the birth rate in the U.S. is fairly trustworthy, compared to say the system that manages elections in Russia, but that trust is totally a function of my model of the world. The data you gather depends on your methodology. Some methods may be better established and may have more evidence in support of them, and the data they gather may really seem reliable, but we also thought that the earth was standing still for a very long time.

Fact just isn't an epistemological category that I have, and it's not one that I find useful. There are only models. Some models are more descriptive and better than others, some are more supported by evidence. But there aren't facts, there are no fixed points that I'm 100% sure are true. I consider my knowledge that 2+2=4 to be close to certain as anything just about anything else I believe, but I hesitate to call it a fact. I have that belief because it's always been true in the past and my brain has learned that induction is reliable. I could be convinced that 2+2=3, and if you believe something only because you have evidence to support it, then you must have a model that translates between the evidence and the belief.

Because the rate of climate change during the Pleistocene would have made long term forecasting difficult.

Huh? Can you, um, provide some links?

I'm hardly an expert on this, but searching for Pleistocene climate variation gives results like this:

"In addition to the well known millennium-scale stadial and interstadial periods, and the previously recognized century-scale climate events that occur during the Allerod and Bolling periods, we detect a still higher frequency of variability associated with abrupt climate change."

"The seasonal time resolution of the ECM record portrays as aspect of the climate system that consistently and frequently chnages between glacial and near-interglacial conditions in periods of less than a decade, and on occassion as rapidly as three years."

Climate Change: Natural climate change: proxy-climate data

The idea that people aren't, by nature, optimal decision makers is one of the core ideas of LW.

We're not talking about optimal decisions. We're talking about not screwing up. Humans are the most successful species on this planet -- they are capable of not screwing up sufficiently well.

We are specifically talking about the claim, "Would you seriously argue that people choose to have children as a reasonably optimal selfish way of guaranteeing that they continue to have enough to eat once they're no longer capable of working?"

I am not making the argument that there are no advantages to having and raising children from a retirement perspective. I am making the argument that it is unlikely that people choose to have children in order to obtain those advantages. I am making the argument that the decline in birthrate in unlikely to be due to people adjusting the number of children they have as part of a retirement plan. The success of a species has very little to do with the ability of individual members of that species to plan in such a way as to maximize their own well-being. Ants are collectively one of the most successful organisms in the world, but they certainly don't engage in long term planning.

Indeed it the success of the human species that I would cite as evidence for my assertion that human behavior is more closely linked to genetic self-interest than to personal self-interest. Cultural and social success is a huge factor in genetic self-interest. There's a reason that humans have large brains and devote so many resources to processing social relationships and facial cues. We have equipment for obeying social mandates. We understand them intuitively. We don't have have intuitive equipment for making long-term predictions, since that was selected for.

status ... it seems to be the thing that people care most about after short term economic incentives

Evidence please. People certainly care about status, but I don't think that people always care about money first, status second, and everything else after that.

I consider the word of a Nobel Prize-winning game theorist and economist to qualify as "evidence" on the topic of aggregate human behavior. If you don't consider the opinions of experts evidence, what qualifies?

I don't understand why you think that human allegiances have to be founded on the nuclear family.

They don't have to be, but I think that empirical evidence points to family ties binding more tight than others.

Okay, but that doesn't necessarily matter. The ties don't have to be tight, they just have to be adequate. Also, the parent->child bond is typically tighter than the "child->parent" bond. But even if we add an uncertainty cost to forming non-parent child relationships, it's not obvious to me that children are a good investment. Children die. Children turn out to be non-productive. Children require lots of resources. Even if my teenage apprentice may be less likely to support me, he's still way cheaper to build a bond with and way more likely to survive to adulthood. I don't see any good reason to birth children rather than recruit apprentices.

I'm not sure what you mean by fact.

I mean an observable and testable chunk of empirical reality. Not a theory, not an explanation, not a model.

I don't know that we have access to facts. Everything is interpreted. Everything is a model. Fact isn't a separate epistemological category. There are things we agree on, even things most people agree on, but I'm not sure what hard and fast distinction you could draw between facts and theories.

You are claiming that humans have evolved the psychological capacity to make decades long judgments in a reasonably optimal way

That seems pretty obvious to me. What, you think no one ever saves for retirement? Why do you believe that to be false?

Because humans engage in hyperbolic discounting. Because the rate of climate change during the Pleistocene would have made long term forecasting difficult. Because I don't see evidence of people making medium term judgments in a reasonably optimal way. The idea that people aren't, by nature, optimal decision makers is one of the core ideas of LW.

Unlike planning for retirement, achieving success within your cultures definition of it (i.e. status) is very important from a genetic evolution status

So how come there are so many losers around? X-) Note that culture is a fairly recent development in "genetic evolution" and for a very long time "high status" implied a front row at the feast, but also a front row at the battle. I agree that high status helped survival, but I don't think it helped it enough so that evolution gave a major push to the fight-for-leadership genes.

I'm not actually sure that culture is recent. I would put the origins of culture at least tens of thousands of years ago, which is definitely appreciable on an evolutionary scale.

Also, status isn't necessarily the same thing as leadership, and it seems to be the thing that people care most about after short term economic incentives (e.g. “apart from economic payoffs, social status seems to be the most important incentive and motivating force of social behavior."-John Harsanyi). The prevalence of the human desire for social status seems pretty well-supported by the literature.

P.S. I'm enjoying this conversation.

That, actually, depends on the circumstances. But in any case, do you really suggest making friends as a good solution to who-will-feed-me problem? Don't forget that they will get old, too.

Human tribes have been a thing for about as long as there have been humans. People with an important role in the tribe don't starve to death. And yes, friends age, and so do children. You can make friends that aren't the same age as you. I don't understand why you think that human allegiances have to be founded on the nuclear family.

The reality is precisely what is being debated.

Is it? On which facts do we disagree?

I'm not sure what you mean by fact. You made the claim that in reality people have children because they think it's a good retirement option, and that they choose the number of children that they will choose to have based on how many children they will need in order to make sure they don't starve to death in the real world. You are claiming that humans have evolved the psychological capacity to make decades long judgments in a reasonably optimal way and that they use that capacity when deciding how many children to have. That is a claim about reality. If it were true, it would be a fact. I think that it is false. I think that people choose whether or not to have children based on culture, and that culture is largely determined by the rules "Copy what most people are doing" and "Copy what successful people are doing". (That's not a commentary of the depth or richness of culture. Complex systems often have simple rules.) I also think that successful people in the present and near-past have tended to have less children and I think that the falling birthrate can be attributed to that. I'm fairly sure that the falling birthrate has much more to do with cultural definitions of success than with anyone's concern for feeding themselves 40 years in the future.

Unlike planning for retirement, achieving success within your cultures definition of it (i.e. status) is very important from a genetic evolution status and would be selected for. I think it's much more likely that evolution equipped humans to seek cultural success, than it is that evolution equipped humans to sacrifice having children based on concerns for how best to spend their reproductively inactive retirement.

Parents often devote significant resources to caring for special needs children who are unlikely to grow into good providers.

All the more reason to have a large extended family. These children will grow into adults who continue to need extra support, and there's no reason for parents to support them on their own. The more siblings you have to help out the better.

From a selfish perspective, the correct decision isn't to have more children. It's to kill or disown the ones who not only won't repay your investment, but will actually compete with you for the return on your other investment in your other children.

It's also not totally obvious to me that children are a particularly good investment from a long-term wealth or even a guaranteed income perspective.

This is because you are thinking of wealth as money. For much of the population of the world, and increasingly so as you go back in time, wealth means enough food on the table, enough food in the root cellar to get you through the winter, and enough grain seed to replant + keep you alive a year or two if the crops fail + plus enough to plant again once the famine is over. As long as another set of hands increases productivity, another pair of hands is a good investment.

I have a pretty broad-minded view of wealth actually. If you're a New Guinea highlander you can invest in mokas. You can trade your neighbors for goats or land. You can accumulate social capital by being generous and well-liked. You can enter into partnerships with younger partners. Another set of hands is only a good investment if it offers nearly the best return for investment, which is a much higher hurdle than merely "increasing productivity." It would actually be enormously surprising if the best selfish return you could possibly get for your time and effort was finding a mate and having children, especially given the high infant/child mortality rates. If children were such a good investment then why did we need a modest proposal?

Women in general were low status. Many of their concerns and desires were ignored unless they happened to match concerns and desires that benefitted men. The fact that women didn't have alternatives to being a mother was just a special case of that..

How did men benefit? Did all men benefit? Were the men also constrained by cultural roles that served to benefit women?

women's desires were considered irrelevant by society.

This is too strong a statement

Almost any statement interpreted while ignoring connotation is too strong. "Women's desires were considered irrelevant by society" means "an important set of women's desires relevant to the current conversation were considered irrelevant by society", not "all women's desires were considered irrelevant by society". Don't ignore connotation.

Context is probably a better word to use than connotation.

My argument is precisely that women's desires were considered relevant. I think that society, which, is after all about half women, never has considered the desires of women to be irrelevant nor has it ever considered the desires of men to be irrelevant. Society has definite opinions about what sorts of desires are socially appropriate, but that's very different from considering desires irrelevant. I think that your objection is about a perceived lack of social roles, especially formal social roles, for unmarried women in some subset of human cultures. Most traditional human societies also lack important social roles for unmarried men.

The transition to an emphasis on personal merit as a source of status rather than familial success has created high status social roles for both men and women outside of the context of family and reproduction. Because men were less tied to reproduction both biologically and culturally, that transition disproportionately affected men at its beginning and for a while Western cultures had many social roles for unmarried men and virtually none for unmarried women. But that was a fairly anomalous period in human history, and for the vast majority of history women have been just about as important to human economic production as men, and as the status of child production has continued to drop, fathers and mothers both have encouraged their daughters to pursue education and careers and other paths desires that lead to positions of high social status.

Being low status has always meant being vulnerable to social violence, and ascribing status is one of the ways that societies create and maintain social norms. The attractiveness of a position in society is dictated by the value and status society ascribes to it, and that valuation is always a set of "external reasons". Particularly low status groups or members of society, who are perceived as different or in violation of important social norms are often ascribed the status of "criminal" or "enemy" and are left especially vulnerable to social violence.

women's desires were considered irrelevant by society.

This is too strong a statement. Many women desire to have children. That desire was hardly considered irrelevant by society. Similarly, many women desire to get married or to worship God. These desires weren't considered irrelevant by society. Quite the opposite. It was considered very important that women have these desires. Desires that led to high social status, like wanting to marry a young man in good standing in the community, were strongly encouraged. Desires that led to low or uncertain social positions like becoming a transient were discouraged, and if pursued in spite of discouragement, punished for undermining the social order. Society almost never respects the desire to become a social deviant.

A society that accords value based on nuclear family size has the social roles of mother, father, and provider and ascribes status to its members based on their success in those roles. In traditional societies, both men and women have jointly fulfilled the latter role. The proliferation of new social roles and highly-esteemed places in the community that have nothing to do with the nuclear family, (i.e. having achievements other than children become markers of status) is the reason that men and women both have a place in the community other than as parents and children.

A man living in a tribe of subsistence foragers can't ever choose to become a full-time string theorist. He can sometimes choose to become a full-time shaman or priest. Both professions study mainly imaginary things, the difference is that one of these roles is ascribed status by the community while the other is not.

I don't see humans commonly engaging in a lot of decades off long-term thinking

No particular need. First, it is what happens by default if you don't take heroic birth control measures (remember, no pill or effective condoms), second, it's culturally ingrained, that's what everyone does

I'm a little uncomfortable classifying infanticide as heroic, but that aside I feel like your claim is shifting. At first you claimed that people choose to have children because they are making an optimal selfish long-term retirement decision and that they choose to have children as a good investment in service to that goal. Now you're saying that people don't really choose to have children for that reason, but that they have children in response to biological pressures and cultural norms. But the claim that family size is driven primarily by cultural norms, which are largely dictated by the perception of which behaviors are regarded as high status, is literally my original claim.

It's also not totally obvious to me that children are a particularly good investment from a long-term wealth or even a guaranteed income perspective.

You're a peasant in Mozambique. Or in XII-century France. What are your other options?

Make friends with people that I didn't help create? Accumulate wealth? There are lots of durable human social institutions other than the nuclear family. There are certainly more of them in the modern world, but it's not like all those childless medieval monks starved to death.

But why is that even an option?

You seem to be surprised that what evolutionary psychology says must happen does not happen in reality. I would like to suggest that this a problem for the theory, not for the reality.

The reality is precisely what is being debated. I am making the claim that the choices that populations of people make, esp. with regard to family size, can be understood in terms of evolution and selection, and that they should reflect, in some form or fashion adaptations consistent with genetic self-interest. You are making the claim that people's choices are more driven by their own rational self-interest, and that understanding the incentives available to individual rational actors is the better predictor of behavior. It seems to me that here you're just labeling your claim "reality" and saying that if evolution disagrees with it then that's a problem with evolution.

That doesn't explain why people choose to have small families.

No, but that explains why that choice exists.

Not really. Humans have exercised control over family size for thousands of years via all sorts of different mechanisms. Modern birth control is certainly more convenient than the vast majority of ancient mechanisms, but it's not clear that the increase in convenience is why the modern world is a lot less excited than the ancient one about the command "Go forth and multiply."

Would you seriously argue that people choose to have children as a reasonably optimal selfish way of guaranteeing that they continue to have enough to eat once they're no longer capable of working?

Yes, seriously, I find nothing outlandish about this assertion. Why are you so surprised?

It's not a totally unreasonable argument, it's just very contrary to my personal experience. I don't see humans commonly engaging in a lot of decades off long-term thinking, and child-creating/child-rearing typically seems to be dominated by a lot of deep instinctual emotional cues. Parents often devote significant resources to caring for special needs children who are unlikely to grow into good providers. Parents seem to derive a lot of satisfaction and to compete for status based on the way that their children perform in school or child sports or other competitions, even though these are very weakly linked to any sort of economic productivity. Hutterite communities practice common ownership and thus have a more extensive social safety net than even modern societies, but traditionally have large average family sizes.

It's not obvious to me that humans reproduce for reasons substantially different from the reasons that other animals reproduce, and it's very obvious that most creatures aren't having children in order to secure their retirement. The tendency of parents to take exceptional risks in order to protect their offspring is also better explained by these traits being promoted by genetic self-interest than the idea that children are a rational agent's retirement plan. It seems profoundly weird to me that all the other animals reproduce because their genes tell them to, but humans just so happen to make the same exact decision for a completely different reason.

It's also not totally obvious to me that children are a particularly good investment from a long-term wealth or even a guaranteed income perspective. I feel like if most people directed the same amount of resources into securing their retirement via other means that they typically direct into child-rearing they would often end up better off. It's an interesting thesis though, and it has some neat fits to the data. The falling birthrate, it could be argued, is due to the fact that there are more long-term investment opportunities now than there were in the past and people have chosen to diversify their investments. At the same time, modern decreases in child-mortality and death in child-birth might make children a more attractive investment than they were in the past, so there are definitely some issues.

Because if you're managing the number of your children, you're managing the number of children who'll grow up to adulthood.

But why choose to have fewer children grow to adulthood rather than more? If my children are more likely to survive to adulthood then I should have more children, not fewer, since child birthing and raising is now a better investment than it was before.

Clearly, people are interested in more than that and on a very regular basis choose NOT to maximize the spread of their genes.

But why is that even an option? What evolutionary advantage is so adaptive that even though it leads to obviously maladaptive behavior like choosing not to have children that you could easily support the adaptation is still a net-positive on average?

I'm not sure what the difference is between [Women have attractive alternatives to just being a mother] and "achievements other than sex and children have become markers of status".

The difference is you're talking solely about status and I'm talking about a much wider context.

I think the more fundamental difference may actually be that I'm talking about population level processes and you're thinking about things on the level of individual decision makers. I think most human decisions are constrained fairly tightly by the culture that they find themselves in and that copying high status individuals is one of the driving forces of cultural change. I think cultures that have family size as a primary marker of achievement and status don't create the opportunity for people to support themselves by going to graduate school to study science or math instead of raising a family. Social status is very much about having a place in the community, and cultures don't create good attractive places in the community for occupations with low social status. An individual may choose to pursue a Ph.D. in math rather than a more conventionally high status career in finance, but a society that doesn't see educational attainment as a mark of status isn't going to have a career track for graduate students at all.

I'm not sure that this is true, or maybe I'm not sure that considering things on average is a good measure of surprise. Finding out you were wrong about something is much more surprising than learning something in the first place. Limited reasoners tend to discard alternative hypotheses when something fits the data well enough. Learning that the earth was flying through space around the sun even though it really doesn't feel like it is was much more surprising to me than it would have been if I hadn't seen the ground so stubbornly sitting still for most of my life. I feel like the more I learn, the more surprised I am when something is different than I expect it to be. I may be surprised less, but my increased confidence in my model makes those surprises all the more salient.

Birth control is widely available;

That doesn't explain why people choose to have small families. In the Iliad the 50 rooms filled with Priam's sons are a mark of his wealth and power, guaranteeing the success and continuity of his bloodline. They aren't an accident. In developing nations people are proud of their large families and they regard as unfortunate people who only have a few children. Birth control may enable the transition, but it doesn't explain the stark difference in attitude.

Social safety nets (and middle-class wealth) reduce the need for children as someone who feeds you in your old age;

Would you seriously argue that people choose to have children as a reasonably optimal selfish way of guaranteeing that they continue to have enough to eat once they're no longer capable of working?

If you children's chances to survive to adulthood are very high you don't need to give birth to that many;

Why not? It's certainly helps maximize my genetic fitness. In general is an animal discovers a new environment with plentiful resources and no predators it doesn't suddenly decide to have less children, since they now have a higher chance of surviving to adulthood. It certainly doesn't end up with fewer adult children than it had before, but that's exactly the pattern we observe in many developed nations.

Women have attractive alternatives to just being a mother

I'm not sure what the difference is between this statement and "achievements other than sex and children have become markers of status".

The desire for children isn't, in general, a rational one. It is rarely in the rational self-interest of a creature to reproduce. My instinct is that the desire for more/less children is driven more strongly by the selfishness of genes and memes than the selfishness of organisms. Either way, the genetically maladaptive decision to limit reproduction in spite of being able to easily feed larger families is certainly not limited to the LessWrong subculture, however poorly defined that is, but appears to be the social norm in almost all developed nations.