做一个经济学家不容易。因为不能足够精确地计算成本和收益，他们受到企业高管的抨击。利他主义者又指责他们太过于注重成本和利润。对政治家而言，经济学家又是让他们扫兴的人，因为经济学家不允许他们在毫不牺牲的情况下承诺一个繁荣昌盛的前景。一些最诙谐的作家也抽出时间来侮辱经济学家，这些作家包括乔治•萧伯纳（George Bernard Shaw）和托马斯•卡莱尔（Thomas Carlyle）。的确，自从卡莱尔把经济学称作“沉闷的学科”（dismal science）之后，对经济学家的公开批评就一直在持续。

托马斯·卡莱尔生于1795年，卒于1881年，是苏格兰散文家和历史学家。他为写作事业倾尽毕生精力，最终成为世界著名的作家之一。

　　卡莱尔称经济学是“沉闷的学科”，是因为经济学的观点不符合他的心意。

1849年，托马斯•卡莱尔曾将经济学称为“沉闷的学科”，因为经济学竭力主张，由供需决定的市场工资优于奴隶制度和卡莱尔所称的“善行鞭”（Beneficent Whip）。但卡莱尔的观点如今打上了“令人生厌”的烙印。（英文原文见后面）

1826年10月17日，卡莱尔和他的秘书简·威尔斯喜结良缘。大约是在8年后，他的妻子去世。1849年，应当是在此后的15年左右。这位历史学家说，在他妻子死后的15年，他的生活完全变了个样，生活对于他来说只是“苦闷、无聊与孤寂”。

观点不同，又处于心情抑郁期，看经济学当然是不耐烦的。当然，后一个原因是我推测的。

卡莱尔的爱情

简出生在一个富裕的医师家庭，她聪慧、迷人，就是有时脾气坏点儿。夫妻俩虽然有时会发生争吵和误解，但感情还是不错的。

婚后，简仍做卡莱尔的秘书。几年后，简病了，但仍带病工作。由于卡莱尔全身心地投入写作，便也没有劝阻简。简患的是癌症，虽然病情发展很慢，但最终她还是倒下了。尽管卡莱尔深爱着简，但因一直忙于工作，很少能有时间陪她。

简去世了，亲朋好友都来参加了葬礼。那是个令人悲痛的日子，天下着倾盆大雨，道路泥泞不堪。回到家，卡莱尔的心情异常沉重。他上楼来到简的房间，坐到她床边的椅子上。想到自己很少抽时间陪爱妻，不禁后悔至极，恨不得时间能够倒流。他看到简的一本日记在床头桌上放着，便顺手拿起来看。他震惊了，他看到她这样写道：“昨天他陪了我一个小时，我感受到了天堂般的幸福，我真喜欢他总这样。”

他意识到自己忽略了很多。一直以来他都把精力投入到工作中，对妻子那么需要自己竟全然不知，几句令他心碎的话映入眼帘，“我一整天都在倾听，期望大厅能传来他的脚步声，但是现在已经很晚了，我想今天他不会来了。”

卡莱尔又读了一会儿，然后扔掉笔记本，冲出了房间。朋友们在墓地找到他时，他满脸泥浆，眼睛哭得红肿，泪水还不停地从脸旁滑过，他反复念叨着：“假如当初我知道就好了，假如当初我知道就好了......”但为时已晚，简永远离他而去。

简死后，卡莱尔创作就很少了。

THE COST OF CURBS ON IMMIGRATION

Humans don't take kindly to outsiders: history is heaped with the corpses of those who were lynched, bayoneted or gassed because of their race, religion or nationality. Even within the relatively civilised sphere of economic relations, there is plenty of room for discrimination. People earn less because of their race or their sex, even in the richest countries in the world.

For example, according to a recent summary by the economists Michael Clemens, Claudio Montenegro and Lant Pritchett, white men earn 27 per cent more in the US than white women. That figure compares the hourly wage of full-time workers with similar qualifications and experience. Again making best efforts to compare like with like, the economists found that white men earn 7 per cent more than black men in the US. Look back to 1939, and the like-with-like wage premium for whites in the US was 60 per cent. In modern Pakistan, meanwhile, men earn three times as much as equally qualified women. None of these numbers is trivial: most are appalling.

It is even possible – although perhaps only an economist would think it pertinent – to calculate the implicit wage loss suffered by US slaves. Several economists have attempted to do this by comparing the “compensation” – food, clothes, shelter and perhaps some medical care – received by slaves with how much one slave-owner would pay another to rent a slave. Of course, low wages were hardly the chief reason that slavery was an atrocity. Yet had slaves earned for their labour what slave-owners paid each other for it, the wage would have been three or four times higher than the basic subsistence owners saw fit to provide.

There is a huge gap between what slaves would have earned in a free labour market and what in fact they were forced to accept. But the gap is dwarfed by the difference between what a Nigerian-born, Nigerian-educated man could earn in the formal sector in Nigeria, and what he could earn if allowed to work in a rich country – more than eight times as much. Nigeria is an extreme example, but there are many other countries in which all that would be needed to quadruple or quintuple a person's income would be permission to work in a rich country. Restrictions on immigration cause a greater loss of wages than racial and sexual discrimination – and perhaps greater even than slavery. This is what Clemens and his colleagues call “the great discrimination”.

This is unquestionably a research paper with an agenda: Lant Pritchett is a vocal advocate of more liberal immigration rules. Despite the agenda, I see no reason to doubt the numbers. Migrants from very poor countries see huge leaps in wages if allowed to move to wealthy countries – that much is obvious. The question is whether voters in wealthy countries feel morally obliged to take those gains into account. So far, they don't.

Economists have a habit of poking these sore points. Steven Landsburg, author of The Armchair Economist, secured notoriety four years ago by labelling the vice-presidential candidate John Edwards a “xenophobe”, arguing that his protectionism arbitrarily privileged Americans over foreigners and was no better than arbitrarily privileging whites over blacks. Few non-economists see things that way.

Economists have always tended to be blind to distinctions of race, sex and nationality. In 1849, Thomas Carlyle branded economics “the dismal science” for its insistence that a market wage set by supply and demand was superior to slavery and what Carlyle called the “beneficent whip”. His view is now rightly branded abhorrent.

I have no idea how immigration barriers will be viewed by our descendants. But it is worth reflecting, if only for a moment, on the costs they impose on those trapped on the other side.