好人會有好報嗎？那取決于好人對其善待對象的了解有多深。這是從著名的博弈論命題“囚徒困境”得出的中心結論。

Do nice guys ever finish first? It depends how well they know the people they are being nice to. That is the lesson at the heart of the well-known puzzle called the Prisoner's Dilemma.

“囚徒困境”的經典內容是這樣的：兩名嫌疑犯因持槍搶劫被捕，分別關在不同的牢房。警官把出路選擇分別告訴兩人。假如疑犯A坦白，他將被免于起訴，獲得釋放，而他的證詞將用于在法庭上證明同伙有罪，使其被判處五年有期徒刑。

In its classic form, the dilemma works like this. Two people are arrested for armed robbery and placed in separate cells. A detective outlines the options to each separately. If alleged robber A confesses, he will go free and his evidence will be used to convict his buddy, who will get five years.

另一方面，如果疑犯B坦白，他將獲得釋放，而疑犯A將被判處五年監禁。假如兩人都坦白，認罪將獲減刑，使每人被判三年監禁。假如兩人都抵賴得一干二凈，那他們將以非法擁有武器的罪名被起訴，預期將被判處六個月的監禁。

On the other hand, if robber B confesses, he will go free and A will get the five years. If both confess, their guilty pleas will win them a reduction of sentence and each will get three years. And if neither says a word? Then they will be charged with illegal weapons possession instead, for which they can expect six months.

兩個壞蛋在犯罪前曾訂立攻守同盟：假如被捕，他們都將保持沉默，使兩人都能得到最輕的懲罰，而不致相互指證對方有罪。但此刻身陷圄囹，面對冷峻的現實，只求自我保存的私念油然而生。疑犯A琢磨：假如我坦白了，可愚蠢的B遵守諾言，那么他固然會被判五年，但管他呢，我自由了。可是，我能相信他不會也對我這樣嗎？

Before the attempted heist, the two villains agreed that, if arrested, they would keep quiet, which would attract the lightest punishment they could get without implicating each other. But in the gloom of the cell, dark thoughts set in. If I confess, A reflects, and B is stupid enough to keep his part of the deal, he will get five years, but - hey - I will go free. But can I trust him not to do the same to me?

對“囚徒困境”進行研究的人士發現，在人們還可能再遇見的情況下，他們傾向于合作而不是背叛。比如，村里人相互關照，而大城市里的人們形同陌路。再比如，在市內公園里亂扔漢堡包包裝紙的人，卻萬萬不敢弄臟鄰居家的客廳。

What researcherssintosthe Prisoner's Dilemma have discovered is that people co-operate rather than betray each other if they are likely to meet again. So villagers do each other favours while residents of large, anonymous cities do not. Someone who thinks nothing of dropping his hamburger wrapping in a city park would not dream of littering his next-door neighbour's living room.

這種現象很容易用進化論來解釋。找得到協作者的人，比埋頭單干的人更具天然優勢。而在另一方面，只有蠢人才會善待不太可能回報自己的人。常規的經濟學理論也十分認同這種“務實”的行為方式。以盈利為宗旨的企業，在符合其自身利益的情況下(如避免代價高昂的立法或贏得新顧客)，應當保護環境或支持當地的藝術團體。但有人認為，企業為本身的利益而履行其社會責任，無異于浪費股東的資金。

Evolutionary theory finds this easy to comprehend. Those who find others they can collaborate with have a natural advantage over solitary operators. On the other hand, people who offer kindness to those who are un-likely to reciprocate are suckers. Conventional economic theory favours such hard-headed behaviour too. Profit-minded companies should protect the environment or support local arts groups if there is something in it for them: heading off expensive environmental legislation or winning new customers. Corporate social responsibility for its own sake is a waste of shareholders' money.

美國康乃爾(Cornell)大學管理學、經濟學和公共政策教授羅伯特•法蘭克(Robert Frank)在一組論文中爭辯說，生活并非如此簡單。單憑經濟學理論和進化論，如何解釋在“囚徒困境”這樣的一次性事件中，有些人會選擇合作，對自己永遠不會再見到的人“講仁慈”，“講義氣”呢？為什么人們會在自己不會返回的路旁餐廳留下小費？為什么有人會把拾到的錢包交給警察，而他們并不預期會遇到失主，更無望得到酬謝呢？

In this selection of essays, Robert Frank, professor of management, economics and public policy at Cornell University, argues that life is not that straightforward. How do economic and evolutionary theory account for people who choose to co-operate in "one-shot" Prisoner's Dilemmas - who offer kindness or decency to those they will never meet again? Why do people leave tips in motorway restaurants to which they will not return, and why do they hand lost wallets to the police when they never expect to meet the wallets' owners, much less receive rewards?

法蘭克教授的主張是：許多消費者以道德原則指引自己的購買行為，愿意為符合自己的道德標準的產品支付較高價格。

Prof Frank argues that many consumers take a moral approach to their purchases and will pay higher prices for products they consider ethically acceptable. The demand for dolphin-friendly tuna is one example.

法蘭克教授指出，企業履行社會責任，怎么說都是會帶來經濟優勢的。實行較高社會責任標準的企業具有成本優勢，因為雇員愿意以較低的報酬為其工作。相反，對于遭到社會普遍鄙視的企業，人們要求得到額外的報酬才愿意屈尊為其工作。于是，煙草企業要請專家證人到國會委員會的聽政會作證，就不得不支付高額費用，而反對吸煙的積極分子愿意義務作證，甚至自掏腰包承擔旅費。法蘭克教授進一步指出，華爾街的律師事務所不得不支付優厚的薪資，才能招到頂尖的畢業生，而一些為公共利益服務的事務所，則只需用少量代價就能聘用到。

There are, in any event, economic advantages to corporate social responsibility, he says. Companies involved in more socially acceptable pursuits have a cost advantage: employees will work for them for less. On the other hand, people demand a premium to work for companies that the rest of society holds in low esteem. So while tobacco companies have to pay expert witnesses large fees to testify before congressional committees, anti-smoking activists will testify for nothing - and even volunteer to pay their own travel expenses. Wall Street law practices have to pay huge salaries while public interest firms can get top graduates for a fraction of the price, Prof Frank says.

這些主張成立嗎？不見得。大部分研究顯示，消費者對于“道德購買”沒有什么興趣。英國食品分銷協會(Institute of Grocery Distribution)在2002年完成的一項研究報告中指出：“除了自己和家人之外，極少有消費者會考慮，他們的購買決定對其他任何人或事物會產生的影響。”

Do these arguments stack up? Not really. Most research shows consumers have little interest in ethical shopping. In a 2002 study, the UK's Institute of Grocery Distribution said: "Few consumers consider the impact of their purchase decisions on anyone or anything but themselves or their family."

(提倡道德原則的)活動人士稱之為“30:3綜合癥”：幾乎三分之一的消費者向研究人員稱自己是道德購物者；但多數以保護環境、動物或低薪雇員自居的產品，其市場份額不到3%。

Campaigners call it the 30:3 syndrome: almost a third of consumers tell researchers they are ethical shoppers, but most products that claim to protect the environment, animals or low-paid employees have market shares of less than 3 per cent.

曾幾何時，為公共利益服務的律師薪資較低這一現象，可能成為耐人尋味的論據，但在當今印度律師愿意以低于公共服務律師的報酬做華爾街律師工作的背景下，其相關性已經不是很高了。

That public interest firms pay their lawyers less might once have been an intriguing argument to pursue, but is less relevant today when Indian lawyers are ready to do Wall Street work for wages even the public interest types would baulk at.

正如法蘭克教授所承認的，個人和企業固然有不少仁義之舉，但我們不能老指望個人或企業會體面行事。假如社會認為有必要使個人或企業體面行事，它必須拿出法律來規范個人或企業的行為。

As Prof Frank concedes, while there are many acts of individual and corporate kindness, we cannot always rely on people or companies to behave decently. If society thinks it important for them to do so, it should have laws to compel them.

法蘭克教授在書中還提到有意思的一點。他與學生們就“囚徒困境”的各種衍生情形進行的實驗證實，人們基本上還是愿意相互幫忙的，尤其是在他們事先有機會溝通的情況下。不過，有一個群體比其他群體更快地選擇背叛；這個群體就是經濟學專業的學生們。而且，他們學習的經濟學理論越多，背叛的行為也越多。

One final titbit from this book. Prof Frank's experiments with his students on variations of the Prisoner's Dilemma confirmed that people were reasonably ready to help one another, particularly if they had a chance to chat beforehand. One group, however, was quicker to betray than any other: economics students. And the more they had studied economics, the more betraying they did.

譯者/和風