It has not been a good year for homo economicus, rational economic man. American voters elected (narrowly) a president who believes that climate change is a myth and that tearing up trade deals will boost growth and jobs. Britons voted (narrowly) in the referendum on EU membership to set the country on a path that 90 per cent of professional economists said would damage the economy over the medium to long term. 对理性的经济人来说，今年并不是一个好年头。美国选民（以微弱优势）选出了一位相信气候变化是无稽之谈、撕毁贸易协定将会推动增长和就业的总统。英国人在退欧公投中（以微弱优势）让英国走上了一条90%的专业经济学家表示中长期将会破坏英国经济的道路。
Populists have gained and experts, including economists, have lost the public debate in 2016. As populism involves simple solutions to complicated problems, despondent experts think this will not end well: Trumpism will not bring manufacturing jobs back to the Midwest; four years of failing to reduce CO2 emissions can only accelerate the consequences of rising global temperatures. 在2016年的公共辩论中，民粹主义者赢了，而包括经济学家在内的专家们输了。由于民粹主义用简单的方法解决复杂的问题，沮丧的专家们认为结果将不会好：特朗普主义不会让制造业岗位回到中西部；4年未能削减二氧化碳排放只会让全球气温上升的后果加速显现。
One economist who would not have been surprised to see millions of turkeys flocking to vote for Christmas is the late Thomas Schelling, whose recent death deprived economics of one of its most profound thinkers. He was one of the first economists to incorporate now-fashionable behavioural insights into his work. One of those insights is that individuals make choices not only about bread-and-butter issues such as how much to consume and how long to work, but also about what to believe. People’s wellbeing (“utility”) depends also on believing things that make them feel good; we derive what is known as consumption value from certain beliefs, Schelling argued in a 1984 article. 有一位经济学家不会对数百万火鸡纷纷投票赞成过圣诞节感到意外，那就是已故的托马斯?谢林(Thomas Schelling)——谢林最近去世让经济学界失去了最深刻的思想家之一。他是首批将如今流行的行为学理论吸收进自己研究的经济学家之一。其中一个理论是，个人不仅就消费多少和工作时长等生计问题做出选择，而且就信念做出选择。谢林在1984年发表的一篇文章中指出，人们的幸福感（“效用”）也取决于相信能让他们感觉良好的事情；我们从一些信念中获得消费价值。
This implies that some psychological “biases” such as overconfidence and confirmation bias are not happenstance features of the brain but serve a useful purpose, the most immediate being feeling better about oneself. Often, they have positive social consequences. Entrepreneurs need to be somewhat delusional, for example. People who are overconfident tend to work more, save more and retire later. But the social spillovers of delusional beliefs can be extremely harmful. 这意味着，自负和确认偏误等一些心理“偏差”并非大脑的偶然之举，而是为了一个实际的目的，最直接的目的是想让自己感觉更好一些。通常而言，它们具有积极的社会影响。例如，企业家需要有些妄想。自负的人往往干得多、省得多而且退休迟。但妄想信念的社会溢出效应可能非常有害。
There are times when what economists Roland Bénabou and Jean Tirole labelled “Mutually Assured Delusion” (rather than Schelling’s better known “Mutually Assured Destruction”) works to the benefit of all. If, for example, there is a chance of recession, if many businesses are objectively over-optimistic about prospects, their efforts might moderate the downturn. Recessions can be self-averting as well as self-fulfilling. 有时候，经济学家罗兰?贝纳布(Roland Bénabou)和让?梯若尔(Jean Tirole)所称的“相互确证妄想”(Mutually Assured Delusion)（而非谢林更为著名的“相互确保摧毁”(Mutually Assured Destruction)）对所有人都有利。例如，在可能陷入衰退的情况下，如果许多企业在客观上对前景过于乐观，那么它们的努力就可能缓解低迷趋势。衰退既可能自我实现，也可能自我避免。
There are, however, many occasions when contagious denial and reality-avoidance have terrible results. Many corporate or other disasters result from groupthink and the unwillingness to update beliefs when presented with contrary evidence. Dissenters are ridiculed or attacked, as was the economist Raghuram Rajan in 2005, when he warned the monetary policy elite of the likelihood of financial crisis. 然而，在许多情况下，传染性否认和回避现实带来了可怕的结果。许多企业灾难或其他灾难源于群体思维，以及在相反证据出现时不愿改变信念。异议者受到嘲讽或者攻击，经济学家拉古拉姆?拉詹(Raghuram Rajan)在2005年向货币政策精英警告可能发生金融危机的时候就遇到了这种情况。
In fact, the more socially harmful the reality avoidance, the more likely it is to be contagious because it becomes ever harder to admit error and face up to impending disaster; each individual’s stake in the (false) beliefs of others being correct increases. 实际上，回避现实对社会越有害，就越有可能传染，因为承认错误和直面即将来临的灾难越来越难；每个个体在（错误）相信其他人正确时的赌注上升。
One might think that while the masses can become delusional, surely the highly educated are unlikely to turn away from inconvenient truths? 人们或许认为，尽管大众可能妄想，但受过高等教育的人士肯定不太可能回避令人不快的真相？
The evidence — uncomfortable for “experts” — is that while people with a high level of cognitive skill are less vulnerable to some behavioural quirks, such as loss aversion, they are more likely to rationalise away evidence that contradicts their beliefs, especially on ideological issues such as climate change. 令“专家们”难堪的证据是，尽管拥有高认知技能的人不太容易有损失厌恶等行为怪癖，但他们更可能用理性分析来拒绝与自己信念冲突的证据，尤其是在气候变化等意识形态问题上。
Seen in terms of the utility derived from holding beliefs, 2016 has been a perfect storm of “Mutually Assured Destruction”. The realities we face, from the global climate to the war in Syria to flows of desperate migrants, are awful. The comfort gained from denialism is correspondingly great, and the contagion effect stronger. 从坚持信念带来的效用角度看，2016年是“相互确保摧毁”的完美风暴。我们面临的现实非常可怕，从全球气候变化到叙利亚战争到绝望的移民流。因此否认主义获得的慰藉非常大，而传染效应则更强。
When there is any divergence in beliefs between groups, the mutually reinforcing dynamic leads to polarisation, and social media and online news speed up the process. Politicians increase their vote by pandering to the trends, and the media maximise profit by click-based reinforcement of them. 当群体间的信念出现分歧时，相互加强的动态导致两极分化，社交媒体和在线新闻加速了这一过程。政客们通过迎合这些趋势来增加选票，而媒体通过以点击量增强这些趋势来最大化利润。
Halting any self-reinforcing dynamic is tricky. This makes the protection of dissent important, whether that is contrarians in financial markets or political opposition through constitutional mechanisms such as the freedom of speech and independent journalism. 要想把任何自我强化的动态停下来非常难。因此保护异见非常重要，无论是金融市场的反向操作，还是通过言论自由和新闻独立等宪法机制表达的政治反对。
The signs of intolerance of others’ opinions among some politicians and commentators are particularly alarming. In the end, reality catches up with delusionists. If climate change is a hoax, as deniers claim, we have nothing to worry about; if it is not, we will all bear the consequences. True leadership lies in acknowledging different views about uncertain outcomes, not in listening comfortably only to the like-minded. 一些政客和评论人士不容忍其他人观点的迹象尤其令人警惕。现实终会追上妄想者。如果气候变化像否认者宣称的那样是个骗局，我们没什么可担心的；如果不是骗局，我们全都会承担后果。真正的领导力在于承认对不确定后果的不同观点，而不是只舒服地倾听想法相同者的看法。
The writer is a professor of economics at the University of Manchester 本文作者是曼彻斯特大学(University of Manchester)经济学教授
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