【文章标题】：Economists should be worried about birth rates
【文章标题】：经济学家应该担心出生率
【文章正文】： Photo by
Age Cymru
on
Unsplash
【文章正文】： 摄影：Age Cymru，发布于 Unsplash
The Economist
has an interesting article this week, in which
it goes after Daron Acemoglu
. Acemoglu is probably the top economist in the world at this point, having just earned a Nobel prize, and sitting right at the top of the list of most cited economists. So it’s kind of funny that when it talks about people who doubt Acemoglu’s research, the one person it mentions is…me!
本周《经济学人》有一篇有趣的文章，其中对达龙·阿西莫格鲁发起了攻击。阿西莫格鲁可能是目前世界上最顶尖的经济学家，刚刚获得诺贝尔奖，并位居被引用次数最多的经济学家榜首。所以有趣的是，当文章谈到那些质疑阿西莫格鲁研究的人时，提到的唯一一个人竟然是……我！
Give an economist a few drinks, however, and some of them will venture their true opinions about this giant. “Much of his theoretical work is useful, but he uses his models to inform populist policies that have been tried before and failed,” blasts one well-known economist. Some commentators do not require Dutch courage. “I’ve been yelling about Acemoglu for literally a decade,” Noah Smith, an economics blogger, has said, in response to a flurry of online criticism of Mr Acemoglu’s work.
然而，给经济学家几杯酒下肚，他们中的一些人就会大胆说出对这位巨人的真实看法。“他的许多理论工作是有用的，但他利用自己的模型来为那些早已尝试过并失败的民粹主义政策提供依据，”一位知名经济学家抨击道。有些评论者并不需要借酒壮胆。“我公开批评阿西莫格鲁已经整整十年了，”经济学博主诺亚·史密斯在回应网上对阿西莫格鲁先生工作的一连串批评时说道。
(For the record,
The Economist
did not actually interview or contact me for this article. Their quote of me was from
a tweet from June
, which they did not link to in the article.)
（需要说明的是，《经济学人》实际上并没有为这篇文章采访或联系我。他们引用我的话来自六月的一条推文，但文章中没有提供链接。）
It is true that I have been pretty critical of much of Acemoglu’s work over the years. In 2012 I
argued strongly against a paper he wrote
in which he claimed that America is more entrepreneurial than Sweden because America’s weaker safety net forces people to work harder (in actuality,
Sweden
is more entrepreneurial by most measures).
确实，多年来我对阿西莫格鲁的许多工作一直持相当批评的态度。2012年，我强烈反对他写的一篇论文，该论文声称美国比瑞典更具创业精神，因为美国较弱的社会安全网迫使人们更加努力工作（实际上，按照大多数衡量标准，瑞典更具创业精神）。
In 2022 I pointed out
that a famous Acemoglu paper claiming that robots destroy jobs was actually an outlier, and listed a bunch of other papers that reach the opposite conclusion. I liked his book
Why Nations Fail
, but I also admit that
its empirical foundations are fairly shaky
. I didn’t like Acemoglu’s more recent book
Power and Progress
, and I was
highly critical
of a recent paper Acemoglu wrote about AI and productivity.
1
2022年，我指出阿西莫格鲁一篇声称机器人摧毁工作岗位的著名论文实际上是一个异常值，并列举了一堆得出相反结论的其他论文。我喜欢他的书《国家为什么会失败》，但我也承认其经验基础相当不稳固。我不喜欢阿西莫格鲁最近的书《权力与进步》，并且对他最近写的一篇关于人工智能和生产率的论文持高度批评态度。1
I also think
Acemoglu’s argument
that skilled immigration has crippled the American education system — now being
heavily cited by
Breitbart
and such — is extremely implausible.
我还认为，阿西莫格鲁关于技术移民削弱了美国教育体系的论点——现在被Breitbart等媒体大量引用——是极其难以置信的。
But this is hardly newsworthy. I go after Acemoglu’s work because I know he can take it; he’s a titan of the economics field, and I am but a lowly blogger. Nothing I say is going to affect his reputation or his prestige, even if someone at
The Economist
mentions my critiques in an article. Indeed, after the article came out, top figures in the profession rushed to condemn it and to defend Acemoglu.
但这几乎算不上新闻。我批评阿西莫格鲁的工作，是因为我知道他承受得起；他是经济学界的巨人，而我不过是一个卑微的博主。我说什么都不会影响他的声誉或威望，即使《经济学人》的某人在文章中提到了我的批评。事实上，文章发表后，该领域的顶尖人物纷纷谴责这篇文章并为阿西莫格鲁辩护。
The Economist
does list a bunch of — usually justified — criticisms of Acemoglu’s work, but this does not mean Acemoglu has been discredited as a researcher or exposed as overrated; indeed, it would be difficult to name a top economist whose body of work does
not
contain a variety of questionable theoretical assumptions, motivated reasoning, and/or
shaky empirical results
. This is a problem with the field itself, not the man; it’s part of a broader crisis of unreliability throughout much of academia.
《经济学人》确实列出了对阿西莫格鲁工作的一堆——通常是合理的——批评，但这并不意味着阿西莫格鲁作为研究者已经名誉扫地，或被揭露为名不副实；事实上，很难找出一位顶尖经济学家，其全部工作不包含各种有问题的理论假设、动机性推理和/或不稳固的经验结果。这是该领域本身的问题，而不是这个人的问题；这是整个学术界普遍存在的可靠性危机的一部分。
But for that same reason, despite the
Economist
article’s lack of newsworthiness, I think it’s good that the magazine decided to come at the king. Economics is far too hierarchical and closed of a profession. Younger and less accomplished researchers routinely defer to the authority of famous and senior figures, and critics from outside the field are typically brushed off. Exactly how it got to be this way is a topic that deserves a longer post, but I believe the hierarchical, closed culture of econ has resulted in a research literature that has been too skewed toward the priorities and intuition of top authority figures. I thus think it’s generally a healthy thing to tweak the tails of those Olympian figures, as long as criticisms are grounded in substance. As they say, “science is the belief in the ignorance of experts.”
但出于同样的原因，尽管《经济学人》的文章缺乏新闻价值，我认为该杂志决定向权威发起挑战是件好事。经济学这个职业过于等级森严、过于封闭。年轻且成就较低的研究者通常屈从于著名资深人物的权威，而来自领域外的批评者通常被置之不理。它究竟是如何变成这样的，值得写一篇更长的文章来探讨，但我相信经济学等级森严、封闭的文化导致研究文献过于偏向顶级权威人物的优先事项和直觉。因此，我认为只要批评有实质内容，去揪一揪那些奥林匹斯山诸神般人物的尾巴，总体上是件健康的事。正如人们所说：“科学就是相信专家的无知。”
So in that spirit, let’s critique another Acemoglu paper.
因此，本着这种精神，让我们来批评阿西莫格鲁的另一篇论文。
First, the background. Recently, a lot of people (including
myself
, but also
prominent economists
) have begun worrying about low fertility rates. Across all countries — poor as well as rich — fertility
just keeps going down and down
, with no floor in sight.
首先，背景。最近，许多人（包括我自己，也包括知名经济学家）开始担心低生育率问题。在所有国家——无论是穷国还是富国——生育率都在持续下降，看不到底部。
This presents two distinct dangers:
population aging
and
population shrinkage
. Aging,
rather mechanically
, creates a burden for young people, because you have more retirees who have to be supported by each worker, either through taxes or through family support. It also
might
reduce productivity
, for example if older managers are
less innovative
, but that’s more speculative. Population shrinkage, meanwhile, is a threat to
total
GDP, which you might care about if you want your country to be more powerful. There’s also the possibility that a smaller population might reduce growth — by reducing the opportunities for specialization, or by reducing the available pool of researchers.
这带来了两个截然不同的危险：人口老龄化和人口萎缩。老龄化，相当机械地，给年轻人带来了负担，因为每个劳动者必须通过税收或家庭支持来养活更多的退休人员。它还可能降低生产率，例如如果年长的管理者创新性较低，但这更具推测性。与此同时，人口萎缩对GDP总量构成威胁，如果你希望自己的国家更强大，你可能会关心这一点。还有一种可能性是，人口减少可能会降低增长——通过减少专业化的机会，或减少可用的研究人员队伍。
But some people argue that a shrinking population is no problem — or might even be a
good
thing. When you make human workers scarce, it creates an incentive to invest in labor-saving technology, which boosts productivity. This mechanism has been proposed by some growth theorists, and some economic historians, like Robert Allen, even think this is what caused the Industrial Revolution! This effect might be strong enough to cancel out the aggregate effect of population aging, so that society stays just as rich — or even gets richer — due to low fertility rates.
但有些人认为，人口萎缩不是问题——甚至可能是件好事。当人类劳动者变得稀缺时，就会产生投资于节省劳动力的技术的激励，从而提高生产率。一些增长理论家提出了这一机制，一些经济史学家，如罗伯特·艾伦，甚至认为这正是工业革命的原因！这种效应可能强大到足以抵消人口老龄化的总体影响，因此由于低生育率，社会保持同样富裕——甚至变得更富裕。
This is actually a plausible mechanism. I have to say, I’m skeptical that it works in the general case. Human beings aren’t just labor
supply
; they also create labor
demand
. The incentive for businesses to buy new machine tools, robots, AI, etc. is that
someone is going to buy the stuff
they produce with those tools. If you have fewer people, you have fewer consumers. This is probably the reason why
the effect of immigration on wages is typically close to zero
. Babies are not that different from immigrants. A larger market size can also create an incentive for more rapid innovation — in fact,
Acemoglu and Linn (2004)
find that faster population growth increases pharmaceutical innovation.
2
这实际上是一个合理的机制。我不得不说，我怀疑它在一般情况下是否成立。人类不仅仅是劳动力供给；他们也创造劳动力需求。企业购买新机床、机器人、人工智能等的激励在于，有人会购买他们用这些工具生产的产品。如果人更少，消费者就更少。这可能是移民对工资的影响通常接近于零的原因。婴儿与移民并没有太大区别。更大的市场规模也可以为更快的创新创造激励——事实上，阿西莫格鲁和林恩（2004）发现，更快的人口增长会增加制药创新。2
But anyway, the idea that population scarcity stimulates innovation is the thesis of
a new paper
by Daron Acemoglu, David Autor, Keelan Beirne, and Andrew Scott. This is from the abstract:
但无论如何，人口稀缺刺激创新的观点是达龙·阿西莫格鲁、大卫·奥特尔、基兰·贝尔恩和安德鲁·斯科特一篇新论文的论点。以下是摘要内容：
Contrary to the widespread expectation that [low birth rates] hamper economic growth, we find lower birth rates are associated with higher growth in GDP per working-age adult across countries and
higher wage growth
across US commuting zones, with no negative impact on aggregate GDP or earnings. These patterns are not explained by educational upgrading, rising female labor force participation, the declining importance of agriculture, or neoclassical-Solow mechanisms. We argue that they reflect the endogenous,
labor-saving response of technology
to the scarcity of younger workers. Consistent with this interpretation, countries and regions with lower birth rates exhibit more labor-saving patents and growing high-tech activity. There is also
higher TFP growth
across countries and industries. [emphasis mine]
与普遍预期相反，即[低出生率]阻碍经济增长，我们发现，低出生率与各国劳动年龄人口人均GDP的更高增长以及美国通勤区更高的工资增长相关，而对GDP总量或收入没有负面影响。这些模式不能用教育升级、女性劳动力参与率上升、农业重要性下降或新古典-索洛机制来解释。我们认为，它们反映了技术对年轻工人稀缺的内生性、节省劳动力的反应。与这一解释一致的是，出生率较低的国家和地区表现出更多的节省劳动力的专利和不断增长的高科技活动。各国和各行业也存在更高的全要素生产率增长。[强调为我所加]
It’s a
plausible
result. But before we go on to the details of the paper, let’s talk about what this result would
imply
, if it does turn out to be true.
这是一个合理的结果。但在我们深入论文细节之前，让我们先谈谈如果这个结果确实成立，它意味着什么。
One of the paper’s basic theses is that
technological automation raises wages
. That flies in the face of
the empirical work
that Acemoglu has done on robots.
3
It also more broadly seems to contradict what Acemoglu has been saying about AI, both in his research papers and in
his public statements
. In his 2024 paper, “
The Simple Macroeconomics of AI
”, Acemoglu writes that “predicted TFP gains over the next 10 years [from AI] are…predicted to be less than 0.53%.” In his 2021 paper, “
Harms of AI
”, Acemoglu writes:
该论文的一个基本论点是，技术自动化会提高工资。这与阿西莫格鲁在机器人方面所做的实证工作背道而驰。3 更广泛地说，这似乎也与阿西莫格鲁在研究论文和公开声明中关于人工智能的说法相矛盾。在他2024年的论文《人工智能的简单宏观经济学》中，阿西莫格鲁写道：“预计未来10年[来自人工智能的]全要素生产率增长……预计不到0.53%。”在他2021年的论文《人工智能的危害》中，阿西莫格鲁写道：
I argue that if AI continues to be deployed along its current trajectory and remains unregulated, it may produce various social, economic and political harms. These include: damaging competition, consumer privacy and consumer choice; excessively automating work, fueling inequality, inefficiently
pushing down wages
, and
failing to improve worker productivity
. [emphasis mine]
我认为，如果人工智能继续沿着目前的轨迹部署并且不受监管，它可能会产生各种社会、经济和政治危害。这些包括：损害竞争、消费者隐私和消费者选择；过度自动化工作，加剧不平等，低效地压低工资，以及未能提高工人生产率。[强调为我所加]
This stands in direct contradiction to Acemoglu’s new paper with Autor, Beirne, and Scott. If modern automation technologies push down wages without raising productivity, it cannot compensate for population aging in the way that Acemoglu, Autor, Beirne, and Scott claim that it must — and therefore, population aging is dangerous in a way that it wasn’t before.
这与阿西莫格鲁与奥特尔、贝尔恩和斯科特的新论文直接矛盾。如果现代自动化技术压低工资而不提高生产率，它就无法像阿西莫格鲁、奥特尔、贝尔恩和斯科特所声称的那样补偿人口老龄化——因此，人口老龄化以一种前所未有的方式变得危险。
Now, it’s fine for a researcher to find two seemingly contradictory things — or even put forward two contradictory theories — in two different papers. The real world is messy and complicated, and there are plenty of “puzzles” in the literature. But if Acemoglu goes around simultaneously telling us:
现在，研究者在两篇不同的论文中发现两个看似矛盾的东西——甚至提出两个相互矛盾的理论——这没什么问题。现实世界是混乱而复杂的，文献中有大量的“谜题”。但如果阿西莫格鲁同时告诉我们：
not to worry about population aging
, because automation will compensate for it with higher productivity and higher wages, and
to
worry a lot about automation
, because it pushes down wages without raising productivity much…
不要担心人口老龄化，因为自动化将以更高的生产率和更高的工资来补偿它；同时又要非常担心自动化，因为它压低工资而不太提高生产率……
…then we have a problem.
4
……那么我们就遇到了一个问题。4
But anyway, on to the actual details of Acemoglu et al. (2026). First of all, I’m not convinced by their result that lower birth rates raise living standards at the country level. The reason is that once they control for a bunch of stuff — education, urbanization, geographic region, etc. — the result loses statistical significance. Here’s their Table 1, with the estimates I’m talking about circled in red:
但无论如何，让我们来看看阿西莫格鲁等人（2026）的实际细节。首先，我不相信他们关于低出生率在国家层面提高生活水平的结果。原因是，一旦他们控制了一堆变量——教育、城市化、地理区域等——结果就失去了统计显著性。这是他们的表1，我所说的估计值用红色圈出：
Source:
Acemoglu et al. (2026)
来源：阿西莫格鲁等人（2026）
In their abstract, the authors declare that “these patterns are not explained by educational upgrading, rising female labor force participation, the declining importance of agriculture, or neoclassical-Solow mechanisms.” But at least some of these patterns can apparently be explained by
other
things — initial education levels, urbanization, and so on — which makes the claim in the abstract a lot less impressive than it sounds.
5
在摘要中，作者宣称“这些模式不能用教育升级、女性劳动力参与率上升、农业重要性下降或新古典-索洛机制来解释。”但至少其中一些模式显然可以用其他因素来解释——初始教育水平、城市化等等——这使得摘要中的说法远没有听起来那么令人印象深刻。5
Also, note that the more controls the authors add, the weaker the estimated effect becomes. That’s
generally a red flag
in empirical papers. No matter how smart and careful you are, there are always things you
don’t
control for, especially in a cross-country regression, since countries differ in so many ways. So if the things you
do
control for tend to weaken your headline result by a lot, you should be worried that the rest of your result can be explained by the controls you left out.
另外，请注意，作者添加的控制变量越多，估计的效应就越弱。这在实证论文中通常是一个危险信号。无论你多么聪明和谨慎，总有一些你没有控制的因素，尤其是在跨国回归中，因为国家在许多方面都存在差异。因此，如果你所控制的因素往往会大大削弱你的主要结果，你就应该担心其余的结果