CAMBRIDGE – Modern macroeconomics often seems to treat rapid and stable economic growth as the be-all and end-all of policy. That message is echoed in political debates, central-bank boardrooms, and front-page headlines. But does it really make sense to take growth as the main social objective in perpetuity, as economics textbooks implicitly assume?
Certainly, many critiques of standard economic statistics have argued for broader measures of national welfare, such as life expectancy at birth, literacy, etc. Such appraisals include the United Nations Human Development Report, and, more recently, the French-sponsored Commission on the Measurement of Economic Performance and Social Progress, led by the economists Joseph Stiglitz, Amartya Sen, and Jean-Paul Fitoussi.
But there might be a problem even deeper than statistical narrowness: the failure of modern growth theory to emphasize adequately that people are fundamentally social creatures. They evaluate their welfare based on what they see around them, not just on some absolute standard.
The economist Richard Easterlin famously observed that surveys of “happiness” show surprisingly little evolution in the decades after World War II, despite significant trend income growth. Needless to say, Easterlin’s result seems less plausible for very poor countries, where rapidly rising incomes often allow societies to enjoy large life improvements, which presumably strongly correlate with any reasonable measure of overall well-being.
In advanced economies, however, benchmarking behavior is almost surely an important factor in how people assess their own well-being. If so, generalized income growth might well raise such assessments at a much slower pace than one might expect from looking at how a rise in an individual’s income relative to others affects her welfare. And, on a related note, benchmarking behavior may well imply a different calculus of the tradeoffs between growth and other economic challenges, such as environmental degradation, than conventional growth models suggest.
To be fair, a small but significant literature recognizes that individuals draw heavily on historical or social benchmarks in their economic choices and thinking. Unfortunately, these models tend to be difficult to manipulate, estimate, or interpret. As a result, they tend to be employed mainly in very specialized contexts, such as efforts to explain the so-called “equity premium puzzle” (the empirical observation that over long periods, equities yield a higher return than bonds).
There is a certain absurdity to the obsession with maximizing long-term average income growth in perpetuity, to the neglect of other risks and considerations. Consider a simple thought experiment. Imagine that per capita national income (or some broader measure of welfare) is set to rise by 1% per year over the next couple of centuries. This is roughly the trend per capita growth rate in the advanced world in recent years. With annual income growth of 1%, a generation born 70 years from now will enjoy roughly double today’s average income. Over two centuries, income will grow eight-fold.
Now suppose that we lived in a much faster-growing economy, with per capita income rising at 2% annually. In that case, per capita income would double after only 35 years, and an eight-fold increase would take only a century.
Finally, ask yourself how much you really care if it takes 100, 200, or even 1,000 years for welfare to increase eight-fold. Wouldn’t it make more sense to worry about the long-term sustainability and durability of global growth? Wouldn’t it make more sense to worry whether conflict or global warming might produce a catastrophe that derails society for centuries or more?
Even if one thinks narrowly about one’s own descendants, presumably one hopes that they will be thriving in, and making a positive contribution to, their future society. Assuming that they are significantly better off than one’s own generation, how important is their absolute level of income?
Perhaps a deeper rationale underlying the growth imperative in many countries stems from concerns about national prestige and national security. In his influential 1989 book The Rise and Fall of the Great Powers, the historian Paul Kennedy concluded that, over the long run, a country’s wealth and productive power, relative to that of its contemporaries, is the essential determinant of its global status.
Kennedy focused particularly on military power, but, in today’s world, successful economies enjoy status along many dimensions, and policymakers everywhere are legitimately concerned about national economic ranking. An economic race for global power is certainly an understandable rationale for focusing on long-term growth, but if such competition is really a central justification for this focus, then we need to re-examine standard macroeconomic models, which ignore this issue entirely.
Of course, in the real world, countries rightly consider long-term growth to be integral to their national security and global status. Highly indebted countries, a group that nowadays includes most of the advanced economies, need growth to help them to dig themselves out. But, as a long-term proposition, the case for focusing on trend growth is not as encompassing as many policymakers and economic theorists would have one believe.
In a period of great economic uncertainty, it may seem inappropriate to question the growth imperative. But, then again, perhaps a crisis is exactly the occasion to rethink the longer-term goals of global economic policy.
Kenneth Rogoff is Professor of Economics and Public Policy
at Harvard University, and was formerly chief economist at the IMF.
Kenneth Rogoff: 反思「增長代表一切」的傳統思維
現代宏觀經濟學通常將快速穩定的經濟增長（economic growth）視為最重要的政策，這一現象反覆出現於政治辯論、央行會議室和報紙頭版標題。但把增長作為永遠的首要社會目標，真的合理嗎？
誠然，許多對標準經濟數字的批評指出，應該採取更廣義的衡量標準定義國民福利，比如出生壽命和讀寫能力等。提出這一觀點的有《美國人權發展報告》，以及最近
的由法國出資、以斯蒂格利茨（Joseph
Stiglitz）、阿瑪蒂亞．森（Amartya Sen）和菲特西（Jean-Paul
Fitoussi）等經濟學家為首的「經濟表現和社會進步衡量標準委員會」。
但除了統計口徑過於偏隘之外，還有另一大問題：現代增長理論無視了人從本質上是社會動物。人類評估自身福利的基礎，是他所能看到的周邊情形，而不僅僅是絕對標準。
經濟學家伊斯特林（Richard
Easterlin）有一個著名的觀察：對「幸福」的調查令人吃驚地表明，二戰以來人們的幸福幾乎沒有增長，儘管趨勢收入增長相當大。不消說，伊斯特林的
結果對貧窮國家來說並不成立，在這些國家，收入的快速增長通常會使社會享受到較大的生活改善，而生活的改善被認為與任何總體福利（不管用什麼標準衡量）密 切相關。
不過，在經濟體發達，基準行為毫無疑問是人們評估自身福利的重要因素。那麼一般化的收入增長便不可能像相對於其他人的個體收入的增 長那樣，能夠決定一個人的幸福。此外，由此產生的一個相關議題是，基準行為還可能暗示，相對傳統增長模型，我們必須以不同的算術計算增長和其他經濟挑戰
（如環境破壞）之間的權衡。
人們沉緬於試圖永久最大化長期平均收入增長，而忽視其他風險和考慮，這看起來有一定的荒謬性。我們來做個簡單的 思想實驗。想像一下，人均國民收入（或某個更廣泛的福利衡量標準）在接下來的幾百年時間裏，每年固定增長1%，這個增長率，大體上就是近年來發達國家的趨
勢人均增長率。若收入的年增長率為1%，那麼70年後出生的人將享受到兩倍於今日水平的平均收入。在200年後，收入會增長8倍。
假設我們 生活在一個增長得更快的經濟中，人均收入每年能增長2%。在這一情形中，人均收入每過35年便可翻一番，增長8倍只需要100年時間。最後，問問你自己，
花100年、200年抑或1000年讓收入增長8倍，對你有區別嗎？擔心全球增長的長期可持續性和持久性有意義嗎？擔心衝突或全球變暖會造成災難後果，從
而導致社會未來幾百年內脫軌，難道不是更有意義嗎？
經濟競賽專注長期增長
或許多個國家緊抱增長不放的深層次理 由，來自對國家地位和國家安全的擔憂。在1989年的名著《大國興衰》（The Rise
and Fall of the Great Powers）中，歷史學家甘迺迪（Paul Kennedy）總結道，從長期看，一國相對於對手的福利和生產力從根本上決定了它的全球地位。
甘迺迪將最主要的注意力放在軍事實力上，但在當今世界，成功的經濟體在多個領域都享受着超凡的地位，世界各國的決策者都無可厚非地糾結於國民經濟排名。角逐
全球實力的經濟競賽專注於長期增長，這不無道理，但若這一競賽真是專注於長期增長的中心理由的話，那麼我們就需要重新思考。
作為長期戰略，專注於趨勢增長並不像眾多決策者和經濟理論家那樣無比重要。
在面臨重大經濟不確定的時代，質疑增長的必要性似乎有些不合時宜。但是，我要再次指出，危機正是反思全球經濟政策長期目標的好機會。
作者為哈佛大學經濟學及公共政策教授，國際貨幣基金組織前任首席經濟學家。