The argument that long-run-sustainable liberalism requires growing abundance is solid. The argument that growing abundance requires a high birthrate is less so. The key problem with it is that the long run here is quite long: South Korea has had below-replacement birthrate since the 1980s and today has among the lowest rates in the world. Would you describe it as a risk-averse, anti-innovative society? I wouldn't.
Moreover, the medical extension of existing lives, and especially of healthspan, can make the long run still longer-- not just by keeping the population from dropping, but by lengthening the span of time for which people are young at heart and in mind, creative and innovative.
Now at some point, as with immigration, this will hit a limit. But suppose, as seems likely, that we can use immigration and life extension to keep economic growth going well into the 22nd century, even as global population stabilizes and then slowly declines. That's a pretty good runway for our efforts to either bioengineer more lives, as you say-- or to accelerate innovation-per-person-lifetime further, perhaps with the help of stronger AI-- or both.
So there is plenty of reason to believe that the theoretical problems with low birthrates will not materialize in practice.
Additionally, one wonders about what life would be like in a world without uncles, aunts, siblings or cousins. It’s one thing to be an only child, however a society of only children would be uncharted territory.
The argument that long-run-sustainable liberalism requires growing abundance is solid. The argument that growing abundance requires a high birthrate is less so. The key problem with it is that the long run here is quite long: South Korea has had below-replacement birthrate since the 1980s and today has among the lowest rates in the world. Would you describe it as a risk-averse, anti-innovative society? I wouldn't.
Moreover, the medical extension of existing lives, and especially of healthspan, can make the long run still longer-- not just by keeping the population from dropping, but by lengthening the span of time for which people are young at heart and in mind, creative and innovative.
Now at some point, as with immigration, this will hit a limit. But suppose, as seems likely, that we can use immigration and life extension to keep economic growth going well into the 22nd century, even as global population stabilizes and then slowly declines. That's a pretty good runway for our efforts to either bioengineer more lives, as you say-- or to accelerate innovation-per-person-lifetime further, perhaps with the help of stronger AI-- or both.
So there is plenty of reason to believe that the theoretical problems with low birthrates will not materialize in practice.
Additionally, one wonders about what life would be like in a world without uncles, aunts, siblings or cousins. It’s one thing to be an only child, however a society of only children would be uncharted territory.