(This isn't the only goal of importance, or even necessarily the most important one. For example, it totally ignores personal happiness. But it is one important goal, and here are some of its consequences. I'm thinking about the United States.)
Evolution of the human race is real. Although the government is unqualified to judge exactly where it should go, its actions unavoidably nudge evolution. And it is qualified to avoid overpopulation. Society and family influence evolution, but parents should get the final say. I want government to use wealth to nudge where evolution should go.
Where do I want evolution to go? I want people to help mankind. I'll measure personal worth by personal wealth, on the theory that you get paid for doing something someone wants. So I want policies that achieve:
I favor looking at evolution of the family rather than of the individual: child and parent and grandparent. I think most human evolution happens in the difference in number of children between siblings of individual families, rather than across races.
I don't know exactly what useful work is. It's likely to change over time. I personally value intelligence and perseverance and health, but I don't know if those would get selected for. Having work=wealth=children would select people who get paid, and people will pay for all sorts of things.
Eugenics has a bad name mostly because Nazis used it to justify killing people. It also is frowned upon because it was originally used by the government, or some other power, to encourage one race or one set of traits over another. Mankind also has a long history of genocide, and class structures keeping social standing constant across generations regardless of merit.
The moral is clear: the only ones qualified to judge whether a child is born are the mother and father, and nobody is qualified to kill off people after they are born. And everyone should have the opportunity to rise to their level of ability.
Parents generally work hard to give their children the best opportunities they can. It's baked into humans: long childhood, marriage, menopause, living for decades after menopause, grandparents helping with grandchildren. But this contradicts having a level playing field for all children. So be it.
Human evolution aims at whole families, not just individuals.
Although the overall birthrate should be about 2.1, a married couple cannot have 2.1 children. Part of modern culture is the belief that nobody should have more than 2 kids, or we'll overpopulate the planet. This is the wrong goal.
A better goal is, if your parents had n kids, they are entitled to 2.1*n grandkids. If they had 1 kid they get 2 grandkids. If they had 5 kids they get 11 grandkids. Then it is up to the siblings to decide amongst themselves how that gets done. Some will have none, and some need to have more than two. A married couple get two numbers to aim for that way, one from each pair of parents, so you can't always hit 2n grandkids for everyone. Do the best you can.
If you're doing well financially and you're willing to raise kids, then you're probably the sibling who should have more than two kids. If you don't want kids, then don't have any. I think most human evolution happens between siblings, rather than between races.
Parents and grandparents should give their kids all the opportunities they can. This means their playing field is better than kids whose parents don't give them as many opportunities. That's OK, humans have evolved to depend on their parents doing this. They should try to give children inheritances too.
A wealthy sibling with few kids should financially aid siblings with kids. This is a way for the family to divide up labor: one sibling earns the money and the other spends their time raising kids.
Government is unqualified to say who is good or bad. But it's well placed to avoid overpopulation. And a lot of government actions unavoidably give evolution small nudges. So government does have a role, and it should be aware of it and pursue it on purpose.
Rather than having government decide who should be selected for, I want wealth to decide. But I want wealth to represent useful work done. The government has a role there too, making wealth more closely match useful work done. The American dream also assumes that wealth matches useful work done. Making work=wealth more true is a good goal for government.
Inheritance: people have evolved to depend on their parents and grandparents, but that contradicts having a level playing field for individuals. I want to encourage modest inheritance but not excessive inheritance. Excessive wealth is actually a good thing for people who have earned it, because their earning it suggests they know how to leverage that money to society's benefit, but the same does not go for their children.
There are nudges available to the government about work=wealth. Most of these are revenue-neutral, and are viewed as increasing social justice.
Does work=wealth say anything about the ideal rate of inflation per year? I don't know. Inflation decreases wealth over time. The US has historically treated both 0% and 2% as ideal, with negative and over 5% as definitely bad. 2% has the effect of giving wealth a half-life of 35 years if it does not earn interest. Stock market gains average over 5% per year, so accounting for inflation, wealth in the stock market doubles every 23 years or faster.
There are nudges available to government to encourage wealth=children. Some are almost invisible, others are quite intrusive. Some of these nudges are very cheap, some are very expensive. A common theme is that a dollar of tax or benefit matters to people in inverse proportion to their wealth, so government taxes and benefits affect the very poor the most. Avoid policies that encourage the very poor to have more kids than everyone else, because those are encouraging evolution to select against doing useful work.
The oddest idea here is disallowing welfare for people who have had one or more children and aren't sterile. Without it, eventually evolution will breed a class that does no work and has more than 2.1 kids on average and purely lives off government handouts. Welfare for people who haven't had children yet is OK: they can have a kid (and lose welfare), but if they have to stop at 1 kid a parasite class will die out. Welfare for sterile people is OK too, since they can't breed a parasite class. The only people who get hit are those who have had one child and may have more. They can have all the children they want, but they should be able to pay for their children (so wealth=children). And this doesn't have to be all-or-nothing: welfare could be cut by some percentage. Encouraging grandparents and siblings to help parents who are denied welfare makes this more feasible.
I don't believe society would disallow welfare for overproductive parents unless there's a big historical episode to point at for why not to do it. The majority can't be persuaded otherwise, I mean, think of the children! Even if a society gets it right initially without that, it's likely to get reverted later because there's no compelling anecdote for why to enforce it. So, don't put much effort into this rule yet.
Overpopulation forces a bunch of evolutionary goals I don't care about, like surviving famine disease war and misery. If we can prevent misery in the first place then those goals don't matter. Avoiding misery is also an important non-evolution-related goal.
Population growth is driven by birth rate, death rate, and immigration. An important non-evolution-related goal is for the government to try to minimize and postpone death. Immigration I think should be ignored in the context of overpopulation: it's about one place being better than another. OK local housing districts have a lot of control over how good a place to live they are, but they generally try to be as good as possible, rather than making themselves worse in order to scare people away. The government should only control overpopulation through the birth rate.
Government's place in controlling overpopulation is in nudging the birth rate. The replacement birth rate is something like 2.1 children per adult. If the rate is higher than that, government should nudge it down, and if it's lower, government should nudge it up. Though if people are unwillingly starving to death, perhaps the population is too high and the birth rate should be lower than 2.1. And if the state is giving away free property to anyone willing to move there, perhaps it should be higher than 2.1. The birth rate is averaged over thousands or millions of people, so the government doesn't need to tell any one person whether to have children or not. It just needs to influence the final sum.
Nudges available to the government that influence the birth rate:
Today, the US population is growing, but only due to immigration (because the US is a nicer place to be than some other places). The actual birth rate is below 2.1. So the US should be encouraging citizens to have slightly more children. I think the most promising place to start is in culture: teach people to give their parents 2n grandkids, rather than teaching them to have no more than 2 children. Also teach them that the well-off have a responsibility to have more children.
A huge and growing portion of US government expenditures is medical bills. It isn't clear to me that the evolutionary viewpoint has anything to say about those one way or the other. I think social security is a much bigger bang for the buck than medicare, but I don't have an evolutionary argument for that, because old people don't breed.
The government should make it medical malpractice to start a treatment without the patient knowing if insurance will cover it, and if insurence won't cover it, exactly what its cost will be. Which means doctors need their own insurance policies for operations, so they can charge patients a predictable amount up front yet get reimbursed from insurance for whatever the actual costs are. This lets people make informed decisions about their medical treatment, which should reduce US medical costs. This would make US expenses more sane, which might allow funding college.
Notice that if old people lived twice as long, but still couldn't have children, that has just about no effect on evolution, and can at most double the population. Improved technology can cope with a one-time doubling of the population, so increasing life expectancy in old age isn't something to worry about from the point of view of overpopulation. But overpopulation cares a lot about changes to the number of children people have and the rate of childhood survival. Postponing menopause would be much more dangerous than extending life expectancy.
Rape should not be evolutionarily rewarded. Not only should abortion be allowed (even encouraged) in the case of rape, in clear-cut cases, the punishment for rape should be sterilization of the rapist. Involuntary sterilization is the same thing as death from an evolutionary perspective, so there should be a high bar to pass before applying that punishment.
If you have an inheritable disease but don't know what genes cause it, not having children remains the only way not to pass it on. So the government funding research into genetic diseases is a good, since people with genetic diseases aren't entirely bad.
The biggest control you have over evolution is which spouse you choose, and how many children you have. Your children will inherit their looks, their abilities, their strengths, their weaknesses, their diseases, from your spouse. Your spouse will become more like their mother and father as they get older. Are you sure you want to choose this spouse, and not some other one? By choosing your spouse, you are choosing what your children will be like.
Your children may not inherit your interests, will probably not inherit your personalities, and will almost certainly not inherit your goals. They'll mostly get your looks and abilities.
Genetic testing allows parents to use abortion as a way of choosing against whatever traits they choose. Would-be parents should be able to get a genetic profile of the fetus, and should be allowed to choose to have an abortion based on it. This allows parents to say, this is something I do not like about myself, I will spare my children from experiencing it. If parents are too choosy, they won't have any children. Being too choosy is clearly a trait that is selected against. I'm not worried about humans evolving to be too choosy this way.
In single-gene genetic diseases, you can still have children and wipe out the disease if you are willing to have abortions. If it takes two copies of the allele to have the disease, someone with the disease having children with a spouse with no copies of that allele will always produce healthy children with one copy (no abortions needed, just careful selection of spouse). Their children with just one copy can avoid children with the one copy by having a spouse with no copies (by careful selection of spouse), plus they can cut out the potential for the disease by aborting the half of their children with that copy.
If mankind can create selective spermicides that can kill off sperm with a bad copy of a gene, then you don't even need abortions to get rid of single-gene genetic diseases. If you have one copy, you can choose a spouse with no copies. If the man has the copy they can use the spermicide to avoid passing it on. If the woman has the copy, and sons who get it use the selective spermicide, the sons won't pass it on, only their daughters can. If women with one copy have less than 4 children on average (so less than 1 daughters on average with the bad copy), the bad copy will eventually die out. And women should have less than 4 children on average otherwise we'll get overpopulation.