女巫的超前思維

　　親愛的經濟學家：

　　Dear Economist,

　　有一個關于古羅馬末代君王塔爾坎(Tarquin)的傳說。一位老女巫走到塔爾坎面前，提出以高昂的價格賣給他9本預言書。塔爾坎對這一提議不以為然。女巫燒毀了其中的3本書，然后提出以原價賣給他剩下的6本。塔爾坎再次拒絕了。

　　There is a legend about the last king of the Romans, Tarquin. An old witch came to Tarquin, and offered to sell him nine books of prophecy at an exorbitant price. Tarquin laughed at the offer. The witch burned three of the books, and then offered to sell him the remaining six for the original price. Tarquin refused again.

　　女巫又燒毀了3本，然后同樣以最初9本的價格向塔爾坎出售剩下的3本。這一次，塔爾坎擔心自己可能會錯失一些寶貴的東西，于是以女巫索要的價格買下了剩余3本書。這反映了什么樣的需求曲線呢?

　　The witch burned three more books and offered to sell Tarquin the three books that were left for the original price that she had demanded for nine. This time Tarquin was scared that he might be losing something precious, and bought the remaining three books for the price that the witch asked. What sort of demand curve is that?

　　克里斯·麥克馬洪(Chris McMahon)通過電子郵件發送

　　Chris McMahon, by e-mail

　　親愛的麥克馬洪：

　　Dear Mr McMahon,

　　忘掉需求曲線吧;這是一個關于經濟盈余分配的兩方談判。塔爾坎始終愿意出高價，但同時希望能夠還價。女預言家("女巫"聽上去讓人不太舒服)則用限制供應的方法來應對，意在推升價格。

　　Forget the demand curve; this is a two-player negotiation over the division of economic surplus. Tarquin was always willing to pay a high price but hoped to get a bargain. The sibyl ("witch" is such an uncouth label) responded with a supply constriction designed to drive up the price.

　　塔爾坎可能會認為，這個女預言家只有一位競爭性買家，如果每位買家都只想要3本書的話，這將形成供過于求的局面。而一旦出現兩位買家只有3本書可買的情況，塔爾坎明白，他正面臨嚴峻的局面，因而搶先報出了價格。

　　Tarquin might have thought that the sibyl had just one rival buyer, and if each buyer wanted only one trilogy, that would be a supply glut. Once there was only one trilogy available for two buyers, Tarquin knew he was in a serious auction and made a pre-emptive offer.

　　還有一種可能性是，女預言家正在解決一個所謂的持久壟斷的問題。塔爾坎知道，女預言家可能會以高價向他出售3本書，然后再回頭以低價出售另外3本或6本。而通過燒毀6本書，女預言家讓自己能夠提出一個真正要不要隨你的出價。這是一種超前思維，但話說回來，她本來就是在推銷預言。

　　Another possibility is that the sibyl was dealing with the so- called durable monopoly problem. Tarquin knew that the sibyl might sell him an expensive trilogy, and then come back later with a cut- price offer to buy a second or third. By destroying two trilogies, the sibyl enabled herself to make a credible, take-it-or-leave-it offer. Forward-thinking stuff, but then, she was flogging prophecies.