It hasn’t escaped the notice of pundits¹ that the political iconoclasts² Bernie Sanders and Donald Trump³ have something in common: they’re sceptical about trade. Trump, for example, has riffed expansively: “We don’t win any more. We don’t beat China in trade. We don’t beat Japan … We can’t beat Mexico, at the border or in trade.” Sanders expressed his concerns with a little more precision: “While bad trade agreements are not the only reason why manufacturing jobs in the US have declined, they are an important factor.”

专家们注意到，伯尼•桑德斯(Bernie Sanders)和唐纳德•特朗普(Donald Trump)这两位政治上的离经叛道者有一个共同之处，即都对贸易抱着怀疑态度。例如，特朗普多次宣称：“我们不再赢得胜利，我们没有在贸易上打败中国。我们没有打败日本……我们不可能在边境或贸易上打败墨西哥。”桑德斯更为有的放矢地表达了他的担忧：“尽管糟糕的贸易协定不是美国制造业就业岗位下降的唯一原因，但它们是一个重要因素。”

Both men have vastly outperformed expectations in the primary campaigns. There are many reasons for that but perhaps the simplest explanation is that freer trade has inflicted⁴ a more grievous toll⁵ than economists⁶, myself included, had expected.

两人在美国总统初选中的表现都比外界预期的好得多。这有许多原因，但最简单的解释或许是，自由贸易深化所引发的负面影响超过了经济学家（包括我自己）的预期。

Fifteen years ago, the conventional economic wisdom was that free trade was almost unambiguously a good idea. Here’s the basic logic⁷. There are two ways for the British to get hold of wine. We can grow and press our own grapes, or we can make something that the French want and trade with them. If we’re good at making, say, computer games and the French are good at making wine, then trading is the better way to get what we want.

15年前，传统的经济观点是，自由贸易几乎毋庸置疑是个好主意。基本逻辑如下。英国有两种方式可以得到葡萄酒。我们可以自己种植葡萄来酿酒，或者我们制造法国人想要的东西，并和他们进行贸易。如果我们擅长制造，比如开发计算机游戏，而法国人擅长酿酒，那么贸易就是我们各取所需的更好方式。

The idea that we might, Trumpishly, “beat the French in trade” sounds appealing but is incoherent. And while a British Sanders might point to the loss of jobs in the UK wine industry, that would miss the gains in the software industry. There is little economic difference between a tariff⁸ on the import of French wine and a tariff on the export of British software.

我们可能——用特朗普式的措辞——“在贸易上打败法国人”的观点听起来很有吸引力，但它是不合逻辑的。尽管英国版桑德斯可能指出英国葡萄酒产业的就业岗位下降，但这种说法没有考虑软件产业的就业增加。法国葡萄酒进口关税和英国软件出口关税在经济学上几乎没有差别。

Here’s a parable⁹ beloved of economists. An entrepreneur announces a technological¹⁰ breakthrough: he has a machine that can disintegrate¹¹ computer game discs and reconstitute the atoms into fine wine. He sets up a factory on the coast of Kent with the machine inside. Computer games go in, and cases of wine emerge. But then an investigative reporter from the Financial Times gains access to the factory and finds that there is no machine — just a dock where a forklift truck operator busily unloads French wine from a boat, replacing it with computer games for export to the French market. Should we care? From the point of view of the British, isn’t France merely a technology for converting computer games into wine?

经济学家们喜欢这则寓言。一名企业家宣布取得技术突破：他有一台机器可以将计算机游戏光盘分解为原子，然后将这些原子重新组合为葡萄酒。他在肯特海岸建了一家装配有上述机器的工厂。计算机游戏光盘进入工厂，然后成箱的葡萄酒就生产出来了。但随后一位来自英国《金融时报》的调查记者进入工厂，却发现根本没有什么机器，只是一个码头，叉车司机正忙着将法国葡萄酒从船上卸下，然后把计算机游戏光盘装上船出口到法国。我们应该在乎吗？从英国人的角度来看，法国不就相当于一种将计算机游戏光盘转化为葡萄酒的技术吗？

With formal models to back up this sort of story, most economists took the view that when countries lower their trade barriers, even unilaterally, they prosper¹². What the British wine industry loses, the UK computer games industry gains. Meanwhile, consumers get better and cheaper wine into the bargain.

随着这种故事受到正式模型的支持，大多数经济学家认为，当各国降低贸易壁垒的时候，即便是单方面的，这些国家也会蓬勃发展。英国葡萄酒产业失去什么，英国计算机游戏产业就获得什么。与此同时，消费者还获得了品质更好、价格更为便宜的葡萄酒。

It was always clear that, despite the win-win nature of trade at the national level, freer trade could create losers — such as British vineyards and French computer game studios. But the conventional wisdom was that these losses were both small and fixable with the right policies of retraining or redistribution. Most importantly, people who lost their jobs could find new ones in booming export industries.

始终明确的一点是，尽管贸易的本质在国家层面上是双赢的，但自由贸易程度加深可能产生输家——比如英国的葡萄酒庄园和法国的计算机游戏工作室。但传统观点认为，这些损失很小，而且还可以通过再培训或再分配的正确政策补救。最重要的是，失业者可以在蓬勃发展的出口行业找到新工作。

Admittedly, it was evident even 20 years ago that median household incomes were stagnating¹³ in the US, inequality was rising in anglophone countries, and manufacturing employment was steadily¹⁴ falling. But these trends seemed to owe more to technological change than to globalisation.

诚然，美国家庭收入中值增长停滞，以英语为母语的国家的不平等现象加剧，以及制造业就业人数持续下降，这些现象在20年前就很明显。但这些趋势似乎更多地源于技术变革而非全球化。

I’ve been phrasing all this “conventional wisdom” in the past tense but, for the most part, it stands up. However, it is acquiring an important and depressing footnote. A new research paper, “The China Shock”, from David Autor, David Dorn and Gordon Hanson, is part of a rethink under way in the economics profession.

我一直用过去时来指称这种“传统观点”，但如今这种观点基本上仍然盛行。然而，现在这种观点得到了一个重要而令人沮丧的注脚。戴维•奥托尔(David Autor)、戴维•多恩(David Dorn)和戈登•汉森(Gordon Hanson)合作撰写的新研究报告《中国冲击》(The China Shock)就是经济学界反思的一个成果。

Autor and his colleagues try to zoom¹⁵ in on the impact of China’s emergence¹⁶ as a trading power. China’s rise has been dramatic, driven almost entirely¹⁷ by internal policy changes inside China, and has had a differential effect on different regions and industries. For example, Tennessee and Alabama are both US manufacturing centres exposed to global competition. But Tennessee’s furniture manufacturing industry is much more exposed to China in particular than is Alabama’s heavier manufacturing industries. This helps the researchers to figure out with more confidence what the impact of the China shock has been.

奥托尔及其同事试图聚焦中国成为贸易大国的影响。中国的崛起引人瞩目，几乎完全受到国内政策改变的推动，对不同地区和行业产生了不同的影响。例如，田纳西州和亚拉巴马州都是美国的制造业中心，遭受全球范围的竞争。但与亚拉巴马州的重工业制造业相比，田纳西州的家具制造业遭受中国竞争的影响大得多。这有助于研究员更加肯定地得出“中国冲击”是什么样的影响。

Autor, Dorn and Hanson conclude that the American workers who have been hurt by competition with China have been hurt more deeply, and for a longer period, than many economists predicted. Employment has fallen in industries exposed to trade competition, as expected. But it has not shown much signs of rising in export-oriented sectors¹⁸.

奥托尔、多恩和汉森得出结论称，受到中国竞争影响的美国工人受到的伤害、以及受影响的时间超过许多经济学家的预期。遭遇贸易竞争的行业的就业人数如预期那样下降，但没有多少迹象表明出口导向型行业的就业人数上升。

The US labour market is less flexible than we thought, it seems. In a simplified economic model, workers move smoothly¹⁹ to a new home, a new industry, even a new level of education. In practice, Autor and his colleagues find that communities hit by Chinese competition often do not adapt; they wither²⁰. It may take a generation or two, rather than a few years, to adjust.

美国劳动力市场的灵活性似乎低于我们的预期。在一个简化的经济模型中，工人会顺利地搬到一个新家、进入一个新的行业，甚至获得新的教育水平。但事实上，奥托尔及其同事发现，遭受中国竞争冲击的群体往往适应不了；他们会萎靡。适应的过程可能需要一两代人的时间，而非几年时间。

In the long run, of course, that adjustment will happen — just as we have adjusted to the decline of agricultural labour or the need for typewriter repairs. But the long run is longer than many economists feared. It is easy to see why supporters of Trump and Sanders have run out of patience.

当然，长期而言，这种适应总会发生，就像我们已经适应了农业劳动力减少或者打字机维修需求下降一样。但这个长期比许多经济学家担心的还要长。不难理解，特朗普和桑德斯的支持者为何已经耐心告尽。