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论坛 经济学论坛 三区 经济史与经济思想史
1996 3
2009-11-12
专访肯尼斯·阿罗


采访 李力行 (北京大学国家发展研究院教师)

翻译 马光荣(北京大学国家发展研究院在读博士研究生)


一、阿罗的学术贡献


问题:作为一位诺贝尔奖获得者,您在社会选择、一般均衡理论和信息经济学等诸多领域都做出了杰出的贡献。您觉得您在这些领域中的工作哪个更为重要?

阿罗:我认为社会选择理论是最重要的。其次,我认为是关于医疗经济学的几篇论文。当然,可能很多人并不会想到这一点。其实不单单是医疗问题,这其中的关键点是信息不对称问题。医疗是一个特殊的行业,其中最本质的问题是,当一个医生面对一个病人的时候,医生知道的信息比病人多。病人无法判断医生是否会给他好好看病。除了医生和病人之间的关系,病人与保险公司的关系也非常重要。病人得病的具体情形医生和病人了解的信息都比保险公司多,因此存在对医疗资源过渡使用的倾向。保险公司很早就意识到了这个问题。信息不对称问题可以再分为道德风险和逆向选择,我不想就此细细展开讲。信息不对称的问题并不只属于医疗产业,在金融管制方面也存在类似问题。信息不对称是经济体系的一个很大问题。在一些情形下,它不怎么重要。在另外一些情形下,它很重要。信息不对称导致的结果就是市场失灵。在我之后,阿克洛夫、斯蒂格利茨和斯宾塞都对这个问题进行了深入的研究。我的第三个贡献是一般均衡理论,当然并不只是存在性定理。这是让我非常骄傲的地方,但这是一个技术性问题。背后的道理很简单,存在性定理是由我和德布鲁证明出来的。虽然这是一项很很艰难的经验性工作,但是却用一种非常严谨的方式来讲明了什么是一般均衡理论。与以往的人相比,我们只是用更清晰的方式来说明一般均衡理论。但我想说的是,这并不是原创性工作,因为想法早就有了。事实上,有四、五位经济学家都在这个方面做过工作。我觉得更重要的是不确定性条件下的一般均衡理论。关于这三个贡献,我就想说这么多。

问题:很多人认为您应当获得三次诺贝尔奖。
阿罗:呵呵。
问题:接下来让我们讨论一下医疗卫生的经济学,您怎么看待当前美国的医疗体制改革?

阿罗;我的第一选择并不是现在讨论中的方案中的任何一个。它应该是一个单一支付体系,就像在欧洲那样。这是其中一个方面。另一个问题是,由于道德风险问题,怎么能够控制成本呢?这其中的困难并不是现有方案是不完美的,而是成本太巨大了。医疗成本在每一个国家都在迅速上升,在美国尤其严重。美国有17%的国民收入都用在了医疗支出上。在我当年写医疗经济学的论文时,这一比例仅有4%。现在美国这一比例比其他任何一个国家都大。加拿大现在是11%。这一比例都在上升,但它不能这样一直上升。一个国家不能把所有的资源都花在医疗支出上。当然你可以说医疗带给我的效用比其它东西都要大,这样如果我们把所有钱都花在上面也不是完全荒谬的。有一种理论说,在美国生命的价值是600万美元。这实际上是用来计算空气污染管制的。这些管制的经济成本你可以计算出来。那么什么是医疗带来的收益呢?你可以说我们有了更好的健康,降低了死亡率。这其实是一个权衡的问题。你可以看到由长寿带来的好处,相对于其他东西,医疗并不是一件很坏的投资。但我不认为这里面有富有说服力的逻辑。医疗护理不是由市场供给的,人们需要交税。然而,税收会产生扭曲,这就是问题所在。现在社会上存在对反对高税率的呼声。但即使存在这种呼声,医疗护理也不能完全由市场来提供。


二、医疗问题

问题:中国也正在进行医疗体制改革,这其中很重要的争论是政府和市场所各自应当扮演的角色。您怎么看待这个争论?

阿罗:这里面有两种想法。一种想法是与经济思考相对的。支付不起医疗服务的人们就不应该获得服务。如果你买不起奔驰车,那么你可以去买便宜的车。如果你买不起房子,你可以住在简陋的房子里。你吃不起肉,你可以吃菜。但我们对待医疗服务却完全不一样。其实历史上并不如此。一个重要的原因是医疗服务可以发挥很大的角色。即使在美国,人们也不否认。所以我们有一种针对退休人群的医疗保障,即Medicare。这是针对所有退休人群的,包括富人。另外,我们还有针对穷人的医疗保障,Medicaid。这是州政府的部分负担。大多数州现在很大开支都花在了Medicaid上。这是一件很不容易的事情,花费相当巨大。它正在挤压州立大学。州立大学现在遇到很大的问题,其中一个重要的原因是州政府的财政开支很大比例用于Medicaid,使得州立大学的经费大大减少。所以我们现在必须做出选择。然而没有人建议取消Medicaid,即使是共和党人。这里面有对支持穷人的一种承诺。当你观察医疗服务的使用时,你会发现它是与收入无关的。美国医疗服务的消费量几乎是与收入无法的。所以我们并没有很好地处理这件事情。现在,我们提出了社会化义务的模式。

第二种想法来自于我的论文,即由于逆向选择问题的存在,医疗保险不能很好的运转。这会花掉很大的成本。一个希望是政府能够采取管制,或者说定量配给。英国就是这样做的,英国是在保持医疗成本低水平方面做得最成功的国家。英国的医疗服务是由政府操作的,大多数地方政府经营医疗保险,而药物则有私人公司生产提供。

还有其他理由来控制医疗成本。其中一个原因是大学里的一些医生,他们比较了美国不同地区,发现有的地区人均医疗花费是其他地区的两倍之多,但产出并没有很大差别。所以这里存在很大的浪费。但很大的困难是我们无法区分哪些花费是有用的,哪些是没用的。由于每个情况都是不一样的,你不可以在外面强加一些东西。但我认为还是有些事情可以做,比如说加强医疗计划间的竞争。在很多国家,比如荷兰、以色列和德国,都有竞争性的医疗计划。很多专家都认为,在美国,一些医疗计划要远好于另外一些计划。而且我认为英国和其他一些国家对新程序、新药物、新手术程序和新设施都有公平的评估,评估它们的价值到底是多少。这个小组可以说,我们买不起这个。当然这种方式可能有点粗糙,其中一个困难是,医生们也并不真正知道成本是多少。而且成本也是在经常变化的。这里面有很多的变化,在一时可以行得通,其他时候未必行得通。你可以把成千个医生召集在一起有效工作,可以收集一些中央信息,以此作为支付的基础。我认为总成本是一件严重的事情。由于存在对高税收的反对,所以我们有很大的累积性的财政赤字。这构成了国家的负债。显然,这是不能一直持续下去的。


三、气候变迁


问题:现在我想跟您探探气候变化的问题。您是否觉得有充足的证据证明是人类活动导致了全球变暖?


阿罗:对于中国来说,这是一个非常重要的问题。我认为毫无疑问气候变化是人类所导致的。当然也存在自然循环,但还有其它因素。这是非常容易回答的。我在二战服役时曾经研究过气象学,相当于气象学的硕士课程。教授说由于工业革命,大气中的二氧化碳量比以前大大增加了。相比于六七十年前,现在的工厂更多,因此碳的负担更重了。我们有石油、天然气和煤,它们都含有碳。我们的工厂、房屋供暖和汽车燃烧掉了很多的煤、石油和天然气。当碳遇到氧被燃烧时,就产生了二氧化碳。越来越多的二氧化碳进入到大气中。也是那位教授说全球气候将会变暖。这是我在1942年接触到的。25年之后,我听到很多人开始担心全球变暖。这里一个困难是我们无法准确测量大气中的二氧化碳量,但是我们可以观察地面上的东西,比如格陵兰岛的冰罩。仔细探索就能得到证据。不管怎样,证据是非常显著的。从19世纪中期以来,人们就观察到冰川在慢慢减少。在阿拉斯加州有个地方叫冰川湾。冰川进入到海中,开始破碎并成为漂浮在海上的冰山。人们对比了1880年和现在的照片,发现这个地方的冰川大大减少了。在世界各地都有类似的令人震惊的发现。所以我认为毫无疑问全球变暖是由于人为因素。这是绝对的。当然你会发现有些波动,有些地方变暖了,有些地方变冷了。有一个重要的证据是,虽然热带风暴的数量并没有增加,但是它们的强度越来越大。关于水温我们并没有很强的证据,因为我们一直没有水温的确切记录。但很少人怀疑海水温度一直在上升,这导致了有更强能量的热带风暴出现。于是我们就有了卡特里娜。


问题:面对全球变暖的问题,中国要在经济增长和减少碳的排放之间做出权衡,你怎么看待这个问题?

阿罗:这的确是一个问题。我认为应该对区域问题进行专门研究,我不清楚中国会受到多大损害。当然中国肯定会从限制全球变暖中获益。因为各个地区间差别很大,很多人对此做过专门研究。但是从全球来看,如果中国跟其他地区一样,它将1%GDP用于限制全球变暖,减少二氧化碳的排放,逐步从煤炭转移到核能和太阳能。在斯坦恩的报告基础上,我做过一些计算。花费1%GDP应该是可以的。虽然短期内会使中国算是掉1%GDP增长率,但长期来看中国会获益。我也不觉得损失掉1%GDP算是很高的成本。美国现在在向这个方向慢慢努力。现在国会有很多类似的议案。其中一些版本的议案很可能会通过,包括一个碳交易系统的议案。我觉得现在中国也应该采取类似措施,因为中国现在时全球最大的碳排放国。

四、中国经济增长

问题:让我们继续讨论中国的问题。你将在周一演讲可持续性的问题。您是否认为中国在过去三十年的高速经济增长是可持续的?是什么因素驱动了中国经济的快速增长?

阿罗:中国处在了一个很好的位置上,它可以吸收利用世界其他国家的技术。中国现在的生产率仍然低于美国,所以可以继续引进技术来缩小这个差距。当然,不能完全依赖技术引进,但是,中国应当向美国学习。我觉得大部分国家并没有做到这一点。中国保持高速增长的时间比日本还要长,所以这是一个新的增长记录。中国要继续保持高速增长还是相当艰难的。因为,容易的东西已经慢慢被用光了,未来将会遇到越来越难的问题。我不能再说具体的细节,因为我并不知道将会发生什么,而且我觉得不会有人知道。


中国已经是每个人都能享受到基本的教育,因此好处很难继续得到维持。由于这样的社会结构,中国将会遇到很多问题,而且是相当长期的困难。但原则上,中国可以继续提高人们的教育水平。毫不怀疑,中国应当继续扩大高等教育的规模,这必将对经济增长是有贡献的。中国可以将更多人移民到沿海地区,这方面将有很大的提升空间。我不清楚中国怎样才能继续保持8%以上的年增长率。但是,或许你们是更清楚。

问题:您提到劳动力迁移的问题。您是否认为城市化是中国经济增长的一个关键点?

阿罗:我觉得你应该已经知道了。城市化并不一定是继续扩大现有城市的规模,也可以是建设新的城市。而美国正是后一种情形。美国有各种各样的地方,有各种各样的小城市。纽约的人口并不比它50年前多多少。人们并不选择移居到纽约,而是依据到各种各样的地方,比如德克萨斯、亚拉巴马或者亚利桑那。亚利桑那的人口已经增长了很多很多。如果回溯到1930年代,洛杉矶只有很少地人口,但现在它是一个大城市。在美国,有一万人口的城市,也有20万人口的城市。我现在住的地方在旧金山的南边,但60年前我搬到那的时候,这还是一个能产出高质量水果的农场。这个地方的人口增长很快。在这一地区,San Jose并不是特别有名,但它现在实际上要比旧金山还要大。很多社区,包括硅谷,都有大量的人口。

所以我的答案是中国不一定按照目前的城市化模式。有很多人认为,经济增长是由城市化带动的,大城市使得有各种想法的人得以相互交流。我觉得上海和北京都在越来越大,中国应当发展新的城市。


附英文原稿:

An Interview with Kenneth Arrow



Lixing Li

November 5th, 2009





Part 1 - Summary of contributions

Question: You are a Nobel Prize winner, you have done great works on social choice, general equilibrium, economics of information, and many other issues, how do you rank the importance of these works?

Kenneth Arrow: I would say social choice is my No. 1. For No. 2, somebody may not think of it, I think it is my paper on the economics of medical care. It is not just the medical care; it is the whole idea of asymmetric information being the central problem of medical care. What makes it the special industry, what are the problems with it is that, essentially, when a doctor meets a patient, the doctor knows more than the patient, therefore the patient is not able to say whether the doctor is doing a great job. There is this relation between the doctor and the patient on the one hand, and there is also a relation with the insurance company on the other hand. The point is that the details of the case are onto the doctor, and maybe onto the patient, but not so much onto the insurer. Therefore there will be tendency to overuse the medical resources. The insurance company has recognized this long time ago. There are certain categories called moral hazard and adverse selection … I do not want to go through the whole lecture. It turns out this is not only the medical care question, and in particular, it is the financial regulation and a number of other things. The idea of this asymmetric information is a problematic property of the economic system. In some places it is less important; in some places it is more important. The result is that the market may fail. Subsequently there is a great literature by Akerlof, Stiglitz, Spencer and other people exploring different aspects of that matter. My third contribution would be the general equilibrium, but in particular not so much the existence theorem. I am very proud of it, but it is technical problem. The idea is being around, the proof of the existence was what Gerard Debreu and I did. It was a very empirical and hard work, and it really involves stating what general equilibrium was in very careful way. We simply state what the theory said in a much clear way than anybody else has done. But I would like to say it was not so original because the idea has been around. In fact, four or five people were working in the same direction. I think what is more important is the general equilibrium with uncertainty. I would like to say these are the three most important contributions.

Question: Some people thank that you should have won the Nobel Prize for three times.

Kenneth Arrow: Well…(Laugh)




Part 2 - Medical care

Question: Now let’s talk about the economics of medical care. What’s your opinion on the current U.S. medical care reform?

Kenneth Arrow: My first choice would not be any of the plans being discussed now. It would be a single payer system, as you have in most European countries. That’s one aspect. The other thing is, because of this moral hazard problem, how do you control costs? The trouble is it is not just a perfectionism idea; the costs are just absolutely enormous. Medical costs are growing relative to other things in every country. The United States has the biggest fraction; about 17% of national income goes to medical care. When I wrote that paper 47 years ago, the percentage was 4%, now it’s 17%, which is bigger than any other country. Canada is like 11%. But they are all going up. The question is somehow this can’t just go up. You can’t have the whole resource of the country just going to the medical care. Although you could argue that medical care gives you something more valuable than most other things. So it is not entirely ridiculous that we are spending all these money. We have a theory that life is worth 6 million dollars in the U.S. This was actually used for determining air pollution regulations. There are economic costs with these regulations that you can tell. So what’s the gain? Typically you have some health gain. Usually it reduces the number of death. So it’s a tradeoff. You can see there are gains in longevity due to medical care. Medical care is not a bad investment compared to other things. So I don’t think there is a strong argument to say. Medical care is not supplied by the market, which means you have taxes, and taxes create distortions, and that’s the problem. There is resistance to higher taxes. Whatever is this resistance, medical care is not going to be paid through the market, and medical care can’t be paid through the market completely.

Question: China is reforming its medical care system. There is a debate on the role of the government and market. What do you think is the key in this debate?

Kenneth Arrow: Well, there are two ideas. One is somehow contrary to most economic think. People who can’t afford medical care should get it anyway. Usually we say if you can’t afford Mercedes Benz, you drive cheap cars. You can’t afford good house, you live in poor house. You can’t afford meat, you eat vegetables. We treat medical care differently. That’s new. That was not historically the case. And one of the reasons is that medical care can do much more. Even in the U.S. nobody is really saying let’s undo it. So we have a program for the retired people, Medicare. This is for all retired people, including wealthy people. Apart from that, we have a medical care program for poor people, Medicaid. It is part of states’ burden. A major part the expenditure in most states today is on Medicaid. It is not a trivial matter, it is pretty expensive. It is squeezing out state universities. They have real problems now, and part of the reason is that state universities are less supported than they used to be due to the high expenditure on Medicaid. So we really are making choices. But nevertheless, nobody is suggesting that we repeal Medicaid, no republican, nobody. Somehow there is a commitment to support poor people. When you look at the actual use of medical care, it is more or less independent of income. The amount of medical care in the U.S. is almost independent of income. So we actually are very imperfectly doing this. Ok, so we have this model of socialized obligation.

The second idea, which comes from my paper, is that even apart from that, medical insurance doesn’t work very well because of adverse selection. It turns to run up the costs. The only real hope is to have government control which says we don’t do certain things. It is called rationing. That is what the British do. The Great Britain is the most successful country at keeping cost down. In Great Britain, the medical service is actually operated by the government. In most places government runs the insurance and the private sector actual supplies the medicine.

There are other needs to control medical costs as well as you can because there is no question there is useless medical care. One of the reasons we know this is that there is a group of doctors from the university, they just compare different parts of the country and they find that some places spend twice as much as per capita medical care than others, but no difference in outcomes. So we have some wastes. The trouble is that it’s not so easy to pick out and say this is useful and that is not. Because every case is different, you can’t impose from outside since every case is really different. It is difficult to do. And I think there are certain things can be done, one is competition, more intense competition among the health plans, and this was done in many countries, say the Netherlands, Israel, the German’s, have competitive plans. The general view among experts is that among plans in the U.S., some are much better than others. And in addition, I think what the British and some other countries do is to have an impartial agency evaluating every new procedure, new drug, new surgical procedure, new device; evaluate how valuable it is. This group could say, no we don’t pay for it, maybe that’s too harsh. One difficulty is that it’s not easy for doctors to really know. Even costs can change. He did it and worked, but that’s … you know there are lots of variations, so that it may work in one time but not in others. If you could pool thousands of doctors to do it efficiently, if you can put some kinds of central information, maybe use this as a base for pay and maybe just announce it, will be relevant. I think the total cost is a serious matter, because we are running into situations where there are resistances to taxes, thus we are running into these huge, cumulative deficits. They are building up our national debt. Obviously this can’t go on forever.




Part 3 - Climate change

Question: Now let’s switch to the topic of climate change. Do you think there is solid evidence that human being had contributed to the global warming?

Kenneth Arrow: It’s a very important question to China specifically. To me there is no question that there is a man-made factor in the climate change. There are natural cycles. That’s true, that is one thing happening. But there are other things. It was very elementary. I studied meteorology during my service in World War II. The training is like a master’s degree in meteorology. The professor said the amount of carbon dioxide in the atmosphere has been greatly increased because of industrial revolution. There are factories, so there are much more burden went on today than 60s or 70s. We have oil, natural gas, coal, they all contain carbon. We burn a lot more and more to run our factories, to heat our houses, drive our transportation, they maybe coal, maybe oil, and all these have carbon. When the carbon is burned with oxygen, it results in carbon dioxide; this just goes to the atmosphere. So the amount of carbon dioxide goes up. Therefore the professor concludes probably there will be global warming. This is my first introduction back in 1942. Twenty-five years later, I heard people worrying about climate change. One trouble is we don’t have measurement going back in time that well. You don’t have direct measure, but people can get things on the ground, like the ice caps in Greenland. You dig down so you get evidence. Anyway the evidence is pretty clear; one thing we have observed for a long time is that glaciers have been retrieving since the middle of 19th century almost everywhere. There is a place in Alaska which is called glacier bay, a place where glaciers come down to the sea, they break off. The whole big piece of glacier becomes iceberg and floats away. They took a lot of pictures since 1880s and compare pictures with pictures took today, you could see there are far less glaciers today than there was. It is true almost everywhere. That is something quite striking. So I think today there is no question that the warming is due to man-made factors. This is absolute. There are fluctuations you find cold here and warm there, keep on finding that. The evidence about tropical storms is that, it does not appear there is any greater number of them; there is conservative evidence that they are more intense. There is no evidence that water temperature is heating because we don’t have good record on water temperature. But there is little doubt that the ocean temperatures are rising. And evidently this gives rise to more intense tropical storms with more energy. Thus we have Katrina.

Question: With global warming, China faces the tradeoff between reducing carbon dioxide emission and economic growth. So what’s your opinion?

Kenneth Arrow: This is a problem. I think regional matters have to be studied specially. I don’t know how vulnerable China is. Of course China would gain by restricting global warming. Somebody has to do a lot research because it certainly differs from place to place. But from a global basis, assume that China is like everybody else, it looks like the world devotes one percent of its GDP to measures restricting global warming, to reducing carbon dioxide, to switching out of coal, to replacing with nuclear, or solar, or something else. I did some calculation based on the Stern’s report. A one percent GDP would pay for itself. So China would benefit greatly. The immediate effect would be a one percent reduction in growth rate for a while. It doesn’t seem to me the cost is very high. The U.S. is moving in that direction very slowly. There are bills now before the congress. Some versions of the bill would probably pass, including a carbon trade system. But I think that China is on the position to gain by going along, because China is now the world’s biggest contributor of carbon dioxide emissions.




Part 4 - China’s economic growth

Question: Let’s continue on China. You will talk about sustainability next Monday. Do you think China’s high growth rate during past 30 years is sustainable? What are the important factors to maintenance this high growth?

Kenneth Arrow: China is of course in a good position because it can take advantage of technologies developed elsewhere. The productivity of China is still relatively lower than the U.S., so just keep on borrowing technologies and narrowing the gap. Of course you can’t just rely on borrowing. But certainly the basic idea is to learn from the U.S. I guess most countries haven’t done that. The rates of growth of China are higher for a longer period than anything Japan has done, so this is a new record for growth. It is hard for me to believe you can continue simply because you are using up easy gains, you must be getting to the harder ones. I can’t say any more details than that because I don’t know yet and I doubt anybody does.

You already get everybody have at least the basic education. So that gain can’t be maintained. I think you get a lot of problems because of this social structure. I think this would be very long-lasting difficulties. But in principle, they could gain a lot by educating your people a lot better. There is no doubt that you can have your higher education to be expanded and that would undoubtedly contribute something. You know obviously there are other regions that are interior which probably you could. You can migrate people from there to the coastal area. There is probably room for gain. I find an eight percent growth almost conceivable, and I don’t know how it can continue. But may be you can.

Question: You have mentioned migration. Do you think urbanization is a key point in China’s growth?

Kenneth Arrow: I assume you already have this. Urbanization doesn’t mean adding necessarily to the existing cities, it could be creating new cities. This is what happened in the U.S. There are all sorts of places: there are very small cities. The population in New York is not particularly bigger than it was 50 years ago. People are not moving to New York, but to all sorts of places. People would move to Texas, Alabama and Arizona. There is lots of growth in Arizona. If you go back to the 1930s, Los Angeles has very few people, but now it is a big city. There are cities with 10 thousand people; there are also cities with 200 thousand people. The place where I live is not San Francisco; it is the area south of it. When I moved there 60 years ago, there were farms that produce very high quality fruit. But the population went up enormously. In that region, San Jose is less well known, but it actually bigger than San Francisco. All those communities, including the Silicon Valley, have a lot of population.

So I think the answer is not necessarily urbanization, the march that continues. But there are lots of arguments that economic growth is increased by urbanization to those people, the serious people with much more contact with different ideas. I think Shanghai is getting bigger Beijing is getting bigger, but there are new cities to develop.




Li Lixing is an assistant professor of China Center for Economic Research at Peking University.



资料来自“中国经济学教育科研网经济论坛”:http://bbs.cenet.org.cn/dispbbs.asp?boardid=92510&ID=410759
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2009-11-12 18:43:38
顶一下 好东西
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2009-11-12 18:58:13
谢谢lz了,好文,顶起来
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2009-11-12 23:39:13
有精力的可以关注阿罗在北大的严复经济学讲座上的内容。
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