I reject your rebuttal based on demographic history, but I am delighted to follow (in a moment) your procedural suggestion that we move on to assuming that the U.N. Low Variant of population growth does take place. Indeed, I think the evidence now suggests that the so-called low assumptions are now much more likely to reflect future reality than the so-called medium assumptions. As--and if--this scenario unfolds, it would entail a momentous change of perspective and, possibly, a change in course--if we're smart enough. The sooner the better.
DEMOGRAPHIC HISTORY: Indeed, some European nations did fall below the replacement level for a few years in the 1930s. But there were several huge differences from the drop in fertility rates that we have witnessed in more recent decades:
1) There was a clear reason for the fertility drop during the Great Depression, namely, the greatest global economic depression the modern world had ever experienced until then. And since. Demographers have always understood that great events can drive fertility down: wars, famine, plague, and economic failure. But in the decades since 1950 we have had, by and large, prosperity, peace, plenty, and good health. What's the reason now? Could it be that modern, industrial, mostly urban societies, on average, settle in at fertility rates well below replacement level?
2) The rates seen now are far lower than experienced in the 1930s, whether measured by general fertility, total fertility, the crude birth rate, the gross reproduction rate or, as you seem to prefer, the net reproduction rate. Further, many European countries never dipped below the 2.1 children-per-woman replacement rate in the 1930s: Among the big four, for example, England and Germany did, France and Italy didn't. Spain averaged more than three children per woman right through the 1930s. So did Greece. Today the average for all European countries, 33 of them, is 1.45 children per woman, according to the 1995-2000 Medium Variant estimate (or 1.38 for the LV). Unbelievably low.
3) The low rates in the 1930s lasted for a few years. The current free fall in fertility has gone on for about a quarter of a century.
4) The fertility drop has taken place in all the developed countries, not just a few, and in most Less Developed Countries as well, albeit from a higher base level.
So, Ken, no dice. The idea that this is just another replay of the 1930s, to be followed, as the day follows night, by a baby boom--just doesn't wash. Low fertility is far lower, far longer, far more extensive--and we're not going to come out of a major depression, because we're not in one. Remember, the central idea in the field of modern demographic studies has been the idea of demographic transition, from high to low, and that, speaking rather roughly, has been going on in the developed world for close to a couple of centuries, and for several decades in the LDC.
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Let's look at that U.N. LV world. That would mean a population of 7.7 billion people in 2050, a global total fertility rate of 1.56, and with total population declining to 3.6 billion in 2150, far fewer people than on the planet today. You say it would be a better place. You say you prefer "the open spaces, less crowding, protection of biodiversity, less global warming, perhaps even some reduction in world poverty."
Let's take your agenda, one by one, backward. (Then mine.) There is a substantial body of evidence, not least that produced by a special panel of the National Academy of Science, which says population growth has little, if any, negative effect on an economy. (After all, the nation that has had the most dramatic and extended population explosion is the one we're in--the United States--and simultaneously it became the most prosperous nation in the world.) Global warming, such as it may or may not be, would, as you say, be less important in an LV world; in fact, I think the whole idea of the warming crisis is vastly overstated in some large measure because we are not going to get to the 11.5 billion people that the Warmists use in their long-range calculations. (Nor anywhere close to it.) The protection of biodiversity is not principally a function of population growth. Rather, it depends on intelligent national zoning policies (wilderness areas, etc.) and the ongoing anti-Malthusian improvements in farming technique, which allow for more food production on less land. This reduces, and perhaps eliminates, encroachment upon the wilderness. Roughly the same zoning model holds true for open spaces and less crowding.
There is one central thought that we shouldn't forget: While population has grown rather dramatically in the last 50 years, the human condition as a whole has improved dramatically. We live longer, healthier, and more interesting lives; we eat better; we are better educated; and we are better housed. That's not exactly a correlative slam at population growth. (Now, if we can just prevent in the 21st century the mass murder that went on for too much of the 20th century.)
There are surely some parts of the LV world that I like. It would, at least, finally silence the thrum of the apocalyptic explosionists. (It would, alas, likely set into motion a new set of tub-thumping Cassandras, telling us that in a below-replacement world there won't be any people left at all after a while. I swear I will not join the chorus.) I also think that, self-evidently, world population has to stop growing at some point. The question before the house, really, is this: Is the current pattern one that gets us there in a healthy way?
I have some serious doubts about that. The European and Japanese fertility rates are, simply, unsustainable. The arithmetic is elementary. Either fertility rates go up substantially or immigration rates go up monumentally, or these nations will suffer massive population loss in the next century. The demographers I have talked to see no reason to suggest that fertility is turning around, nor any good reason to think that it will do so any time soon. Large immigration increases are highly unpopular and potentially destabilizing in these nations. They are not nearly as pluralist as America (and even here immigration is unpopular).
As it happens, these are also the nations that make up a large fraction of what is loosely called "the West." By my lights, the classical liberal culture of these Western democracies--free elections, a free press, human rights, an independent judiciary, and so on--provide the best hope that mankind will move forward. In 1950, roughly 28 percent of the world's population lived in the modern "Western" nations of Europe, North America, and Japan. Today 18 percent do, and in 2050, it will be more like 11 percent. So what? Arguably, a large population is a necessary but not sufficient condition for global power and influence. India is not now a global power of the first magnitude. Belgium never will be.
The West has been the driving force of civilization for centuries. Will it be so when its share of the world's population is only 11 percent? Europe will become an ever smaller picture-postcard continent of pretty old castles and old churches tended by old people with old ideas. Perhaps as LDCs modernize, they will assimilate Western views and values. Perhaps the 21st will be another "American century." Perhaps not, alas.
When people have fewer babies and live longer, the median age of society climbs. We're going to have a "grayby boom." When a population has lots of old people and few young people, the economic base for elderly support programs erode. In 1955, there were nine Americans of working age to support each Social Security recipient. Today there are three. By 2030, the number is expected to be two. In Europe and Japan the situations are much more serious. Where will the money come from? No one knows. Probably from higher taxes or lower benefits. That is, there will be a cut in the standard of living.
Eventually demography blends into psychology. There is likely to be much extra personal sadness ahead. There will be missing children, and missing grandchildren. Demographer Nicholas Eberstadt of Harvard and the American Enterprise Institute looks ahead and writes: "For many people, 'family' would be understood as a unit that does not include any biological contemporaries or peers," and that we may live in "a world in which the only biological relatives for many people--perhaps most people--will be their ancestors." Lots of people without brothers or sisters; uncles, aunts, or cousins; children or grandchildren--lonelier people.
A lonelier world? It's not lonely enough now? Some observers say that in such a world friends and colleagues will become "like family." Do not count on that if you end up in a nursing home. Young DINKs (double income, no kids) may be cute. OLINKs (old, low income, no kids) may be tragic. Clergymen say the saddest funerals are when the deceased has no offspring. Young men say it's so hard to find women; young women say the reverse and worry about the ticking biological clock. Adoption is excruciatingly difficult. Many millions of people who want children aren't having them. People well into their 60s, looking for grandchildren, are asking, "Where's the beef?"
The Jewish population has particularly low fertility rates; many Jewish thinkers now wonder about community survival in America. Black female college graduates have fertility rates as low as Jews--just when it is said that the black community needs role models. Young people, everywhere, say they can't afford to have two children--in the most affluent moment in world history. We worry about family values and family erosion, and seem to forget about family formation.
So, Ken, there is some good news and some bad news about the new situation. To sweep the bad news under the rug is not responsible. We ought to look the situation square in the eye, and ask, "Is there something we should do about it?" and "Is there something we can do about it?"
We should talk about this. I start from one premise: We ought to make it easier for young people who want to have children to have children. Is that so radical?