Assessing Parfit’s Repugnant Conclusion within a canonical endogenous growth set-up

Parfit’s Repugnant Conclusion stipulates that under total utilitarianism, it might be optimal to choose increasing population size while consumption per capita goes to zero. We evaluate this claim within a canonical AK model with endogenous population size and a reduced form relationship between demographic and economic growth. First we characterize the optimal solution paths for any capital dilution function. Second, we prove that while the Repugnant Conclusion can never occur for realistic values of intertemporal substitution in the traditional linear dilution model, it does occur when population growth is linked to economic growth via an inverted U-shaped relationship.     

Utilitarian tradeoff between population growth and income growth

Utilitarian social welfare functions were devised for a world with a fixed population. With endogenous population, Edgeworth conjectured that the Benthamite principle of maximizing total utility (classical utilitarianism) would lead to a larger population size and a lower standard of living than the Millian principle of maximizing per capita utility (average utilitarianism). One objection to the Benthamite criterion was that its application to a world with finite resources often implied large population size in conjunction with an embarrassingly low average standard of living. In a static environment with altruistic parents, this may not be warranted. In a growth situation, this criticism is even less likely to be supported. This paper extends the comparison of classical and average utilitarianism from a static to a dynamic and endogenously growing economy. Using a stylised endogenous growth framework, it confirms that the Benthamite population growth rate exceeds the Millian growth rate. In terms of the rate of growth of per capita income, the reverse is true. Having the standard of living often increasing under the Benthamite criterion, our results thereby depart significantly from the repugnant conclusion levelled against classical utilitarianism.We would like to thank an anonymous referee for helpful suggestions.     

Family Benefits and Fertility: An Econometric Analysis

A population's growth potential is significantly underestimated by conventional calculations of population momentum which assume an immediate drop to replacement level fertility. Here we assume that the growth rate of births linearly declines to zero over a specified time interval, and find simple and intuitively meaningful expressions for the size of the ultimate birth cohort and the resultant population momentum. In particular, we find that the increase in the number of births over the transition is equal to growth at the initial rate for half the time needed to attain a constant birth level. Thus our formula readily calculates the growth potential of a population under a gradual approach to stationarity without the need for a numerical projection. Calculations for actual and hypothetical populations are presented to show the demographic impact of such gradual approaches to zero growth.     

Change of population policy and the population situation in China]

A correct population policy is very crucial to the solution of the population problem, economic development, and social progress. The real situation in China now is a large population, a high rate of population growth, and low level of productivity. Facing this situation, China's population policy should include control of population growth in quantity, a promotion of population quality, and a match between population growth and social and economic development for the final realization of the Four Modernizations. In recent years, under the leadership of the National Committee on Family Planning, together with cooperation from various offices at the local level, a great change has taken place in China's population situation. The fertility rate has declined gradually, and late marriage, delayed births, and a reduced number of births have also become popular. A change in the age structure of the population has also slowed the pace of population growth. A reduction in the ratio of women of childbearing age is also helpful in the control of population growth, and the natural growth rate for the population has declined. This change shows that family planning is working in China and great results have been achieved. To come closer to the national goal of population control, practical work should be focused on rural areas. The rural population constitutes about 80% of total population and the fertility rate in rural areas is much higher than that of the cities. If population control can be achieved in the rural areas, the overall goal of population control for the country can then be achieved more easily.     

A management policy for sika deer based on sex-specific hunting

We consider here a management policy for a sika deer (Cervus nippon) population in the eastern part of Hokkaido. Deer populations are characterized by a large intrinsic rate of population increase, no significant density effects on population growth before population crash, and a relatively simple life history. Our goals of management for the deer population are (1) to avoid irruption with severe damage to agriculture and forestry, (2) to avoid the risk of extinction of the deer population, and (3) to maintain a sustainable yield of deer. To make a robust program on the basis of uncertain information about the deer population, we consider three levels of relative population size and four levels of hunting pressures. We also take into consideration a critical level for extinction, an optimal level, and an irruption level. The hunting pressure for females is set to increase with the population size. We also recommend catching males if the population size is between the critical and optimal levels and catching females and males if the population size is larger than the optimal level. We must avoid cases of irruption or threatened population under various sets of uncertain parameter values. The simulation results suggest that management based on sex-specific hunting is effective to diminish the annual variation in hunting yield. Received: April 8, 1998 / Accepted: December 25, 1998     

俄罗斯人口发展状况及对中国的启示

本文利用俄罗斯的历史人口数据,对俄罗斯人口数量和结构变动状况进行了分析,并对俄罗斯三次人口转型中的社会经济情况变化对人口变动状况的影响进行了分析。结果表明,俄罗斯的人口出生率下降很快,人口死亡率升高,总和生育率已远低于替代水平,因此人口自然增长率迅速下降,总人口数长期处于下降通道,出生预期寿命不增反降,特别是男性出生预期寿命远低于女性出生预期寿命。在推动人口增长的社会经济相关措施实施后,俄罗斯人口数量仍不能增加,这对目前总和生育率已经很低的中国有一定的借鉴意义。     

Strongly pressed by the task of population control

Today, the world population grows at an annual rate of over 80 million. The activities of "the Day of the 5 Billion" sponsored by the United Nations sounds alarm to the world: It is an emerging task to strictly control human reproduction. China, being a developing country, knows only too well the difficulties that over-rapid population growth brings upon economic and social development. Population control is a pressing task. China would like to make the nation prosperous by quadrupling the gross national product (GNP) to US$800 or US$1000 per capita, thus raising the people's living standard to the level of being well-off at the end of the century. The GNP would be quadrupled again to US$4000 per capita with the standard of living raised by the mid-21st century. In order to realize strategic goals, China must strive to control the total population of China at about 1.2 billion at the turn of the century, leaving a better population structure for the next century. At present, China has a population of 1.057 billion and is faced with a new baby boom. It is hoped that under the leadership of the Party's Central Committee and the State Council, governments at all levels, and the people of all nationalities will do a better job in population control by fulfilling the population plan for this year so as to lay down a good foundation for enforcing the plan during the 7th 5-year plan. Meanwhile, China will continue to make new contributions to the stabilization of the world's population together with the UNFPA and other international bodies and friendly countries who support China's population control policy.     

Evolution and population dynamics in stochastic environments

Inter-generational temporal variability of the environment is important in the evolution and adaptation of phenotypic traits. We discuss a population-dynamic approach which plays a central role in the analysis of evolutionary processes. The basic principle is that the phenotypes with the greatest long-term average growth rate will dominate the entire population. The calculation of longterm average growth rates for populations under temporal stochasticity can be highly cumbersome. However, for a discrete non-overlapping population, it is identical to the geometric mean of the growth rates (geometric mean fitness), which is usually different from the simple arithmetic mean of growth rates. Evolutionary outcomes based on geometric mean fitness are often very different from the predictions based on the usual arithmetic mean fitness. In this paper we illustrate the concept of geometric mean fitness in a few simple models. We discuss its implications for the adaptive evolution of phenotypes, e.g. foraging under predation risks and clutch size. Next, we present an application: the risk-spreading egg-laying behaviour of the cabbage white butterfly, and develop a two-patch population dynamic model to show how the optimal solution diverges from the ssual arithmetic mean approach. The dynamics of these stochastic models cannot be predicted from the dynamics of simple deterministic models. Thus the inclusion of stochastic factors in the analyses of populations is essential to the understanding of not only population dynamics, but also their evolutionary dynamics.     

Population and Poverty in Classical Theory: Testing a Structural Model for India

There has for many years been debate over the relationships between population growth rates and poverty. India is a country which provides a good testing ground for hypotheses about this relationship because since Independence a relatively high proportion of the population have lived in poverty; and there also exist reasonable data. This paper develops a simple structural model to investigate the relationship between population growth and poverty in particular, testing a series of hypotheses developed from the work of Marx and Malthus. The data are analysed at state level, and attention is drawn to the problems that this might cause as behaviour is typically determined at the individual household level. The results show that agricultural productivity and the process of landlessness are better predictors of poverty at a state level than the population growth rate. It is argued that the results fit better with the views of Marx than those of Malthus.     

The current situation and tasks of China's population control

During the 10 years from the late 1960's to the late 1970's, China's birth rate declined by 50%. Currently, however, China is in the midst of a baby boom. 3 statements characterize the birth rate: The growth rate is high (birth rate is 21.04/1000 in 1987 and natural increase was 14.39/1000); unplanned births are common; and population growth is varied in different areas of the country (10 provinces show 3rd or higher parity births at an average rate of 20%; the highest rate in a province is 45%). Several measures are suggested to deal with these population problems; increase nationwide awareness of population control; stabilize current family planning policies with only special case exceptions; expand contraceptive services and increase scientific research in the area of family planning; and enact economic and social welfare policies in line with population control.     

人口增长率与人口规模关系的实证研究——基于中国省际面板数据的分析

文章在内生经济理论的框架下推导了在一定条件下人口增长率与人口规模负相关的结论,同时基于1954年至2007年的数据,运用动态面板数据模型验证了人口增长率与人口规模负相关。文章的动态面板协整检验表明,我国人口规模每增加一亿,人口增长率将减少2.13‰,我国人口规模将会达到15.4亿的峰值,然后人口增长率出现负增长。最后文章的格兰杰因果检验也表明,人口规模的变化是人口增长率变化的格兰杰原因。     

The momentum of population growth with time dependent net maternity function

The momentum of population growth problem of Keyfitz is generalized to contain a gradual change of the age-specific birth rate ro the level of bare replacement. Assuming a time dependence for the net maternity function of the form (formula: see text) R being the net reproductive rate, we show that for the Malthusian model the asymptotic birth rate is increased by exp (r/lambda), where r is the rate of increase of the population before t = 0. A numerical method for obtaining the asymptotic birth rate for a general net maternity function with the same time dependence is outlined.     

Optimal population and exhaustible resource constraints

A large literature considers the optimal size and growth rate of the human population, trading off the utility value of additional people with the costs of a larger population. In this literature, an important parameter is the social weight placed on population size; a standard result is that a planner with a larger weight on population chooses larger population levels and growth rates. We demonstrate that this result is conditionally overturned when an exhaustible resource constraint is introduced: if the discount rate is small enough, the optimal population today decreases with the welfare weight on population size. That is, a more total-utilitarian social planner could prefer a smaller population today than a more average-utilitarian social planner. We also present a numerical illustration applied to the case of climate change, where we show that under plausible real-world parameter values, our result matters for the direction and magnitude of optimal population policy.     

中国妇女生育水平变动考证和未来人口发展的策略选择

1990年以来各类人口调查和相关学者的研究结果显示,目前的低生育水平的实现有外在政策强力的作用,更有中国社会经济发展内生化的作用;真实的生育水平既不是调查包括人口普查所显示的那样低(低于1.5),也不是有关部门和政府所想象的那样高。调查显示农村居民平均生育意愿不会高于2个孩子,这是生育率持续稳定的根本。众所周知,为了保证人口稳定持续的发展,应使妇女生育率保持更替水平或至少接近更替水平。从人口发展规律和人口发展与社会经济发展相适应的规律出发,结合当前我国居民生育意愿和生育水平走低的实际,我们应该抓住生育政策调整的最佳时期,调整应该在最佳时期即未来5-10年内完成。     

Intrinsically Dynamic Multistate Models

Multistate life table models, which follow persons through more than one living state, have found increasing use in demographic analyses. Multistate stable populations, however, are infrequently used because the constant rate assumption is quite strong and such populations can take centuries to approach stability. Dynamic models, that is models where the rates can change over time, are examined to derive a new solution for the size and composition of a multistate population in terms of the sequence of underlying population projection matrices (PPMs). Constraints on the subordinate eigenvalues and the subordinate eigenvectors of the time-varying PPMs produce a model population that grows according to the dominant eigenvalues of each time-specific PPM and has a state composition that depends only on the most recent PPM. The two living state model is examined in detail, relationships between the PPM elements and the size and composition of the model are explored, and two illustrative applications of the model are presented.     

Asian and Pacific population targets

2 population targets for the Asian and Pacific regions were established in 1981-82: 1) by the Asian Conference of Parliamentarians on Population and Development at Beijing, China to attain 1% population growth rate for the Asian region by the year 2000, and 2) by the 3rd Asian and Pacific Population Conference at Colombo, Sri Lanka, to attain replacement level of fertility by the year 2000. In an attempt to ascertain whether these targets can be achieved and/or related, the Population Division of the UN's Economic and Social Commission for Asia and the Pacific (ESCAP) prepared population projections in which the 2 targets are achieved. These projections were prepared by aggregating the total population of member countries. When net reproduction rate (NRR) equals 1 (replacement level fertility) it will lead to a stable population with a growth rate of zero. In the short-term a population with replacement level fertility will continue to increase if it has a young age structure due to previous higher levels of fertility. Some projections for the period 1980-2005 are: 1) population growth rate will decrease from 1.78% to 1.05%, 2) total fertility rate will decrease from 3.63-2.11, 3) male life expectancy will increase from 59.8-67.3, and 4) infant mortality rate will decrease from 67.3-34.5. For the ESCAP region, a target of NRR of 1 would be easier to achieve than a growth rate of 1%. The UN projects the total population of the region to be 3,382,000,000 in the year 2000. If the NRR can be lowered to 1 by then, however, the total population would be 3,342,000,000 and if the growth rate can be reduced to 1% by the end of the century the resulting population would be 3,300,000,000. Major demographic benefits will be attained in terms of the age structure of the population if a 1% growth rate is achieved; the proportion under age 15 was 37.1% in 1980 but will be 27.2% in 2000 with a dependency ratio of 48.8 compared to 70.8 for 1980.     

Zero growth of the population of the United States

It is sometimes said that there is no population problem in the United States because the U.S. fertility rate is approximately at the replacement level of 2.1 children per woman. However the population of the United States increased in 1992 by approximately three million people. There are two major causes of continued population growth even when fertility is approximately at the replacement level. One is population momentum; the other is immigration. This paper examines what must be done if we want to achieve zero growth of the population of the United States immediately, without the long delays caused by population momentum.     

Bangladesh: programs geared to meet population goals; communication as a major factor in UNFPA funded projects

The population policy of Bangladesh is aiming for a zero population growth rate at a suitable level of equilibrium. It is hoped that a net reproductive rate of 1.0 will be achieved by 1990, and that by 1985 fertility will be reduced to replacement level. Various measures to attain these goals have been suggested and they include such ones as the integration of family planning programs with other development efforts through a multisectoral approach and the introduction of incentives and disincentives for acceptance of the idea of the small family. Communications by radio and television play a critical role in the program to reduce fertility. UNFPA-funded projects emphasize education, motivation, and communication with the hope of creating a favorable attitude towards family planning and the concept of the small family. Numerous projects in progress are mentioned with regard to their current status. These projects include: rural development cooperatives and population education; pilot projects for family planning motivation and services in industry and on plantations; population education in agricultural extension; strengthening (IEM) information, education, and motivation and training; population awareness for out-of-school youth; a population education program for the Ministry of Education; and a national population information service.     

New Estimates and Projections of Population Growth in Pakistan

Pakistan's population growth rate rose steadily from about 2.6 percent per annum in the early 1960s to a high of about 3.5 percent during the late 1980s. Since then it has declined to an estimated 2.1 percent for 2003. Growth rates calculated from the population censuses, which show a very different picture, are distorted by differential accuracy of enumeration. During the period of rising growth rates, fertility was constant at just under 7 children per woman while life expectancy at birth rose by nearly 20 years. Fertility decline began in the late 1980s, bringing the population growth rate down with it. Remarkably, there appears to have been little change in life expectancy over the past 15 years.     

Momentum and the growth-free segment of a population

In the scenario of a sudden drop in fertility to replacement level. Preston (1986) argued that the population segment under age T, the length of generation, remained growth-free. Here we first present a new relationship for the momentum of any observed population as the ratio of 1) the proportion of the observed population under the mean age at childbearing to 2) the proportion of its life table population under that mean age. We then use that relationship to demonstrate Preston's approximation. Growth factors for other population segments are also presented. When the initial population is stable, momentum can be approximated as a function of the net reproduction rate alone.