蘭嶼雅美族以同易同式交換的經濟實用性

The Economic Utility of Yami 'Like-for-like' Exchange

簡單社會的交換可大致區分為兩大範疇：以有易無式的交換及以同易同式交換。以有易無式的交換簡單說，是將本地充分生產之物，與他地交換本地不能生產之物；本地無法生產之物自然因其稀有而有較高的需求，為了滿足此一需求，必須經過交換的手續來取得，此一交換的經濟意義即是某種需求的滿足。反觀以同易同式交換，經常交換雙方的交換物都是彼此能夠充分生產之物，在交易過程中，既不求交換物量的增加，亦不求質的改變。換言之，從表面上觀之，不經此一交易，交換雙方的需求也各自能夠滿足，因此此種交換從經濟實用的觀點看，自屬多餘冗贅，而此種交換的持續進行也僅能以其「非實用的意義」來思考。本文是利用蘭嶼雅美人在日常生活、三個主要節慶及落成禮等不同場合的禮物交換為例，說明在同一生態區內，以同易同式交換之經濟意義是在彌補因為時間因素導致的暫時性匱乏。簡而言之，以有易無的交換是以本生態圈內可生產之物，以換取本生態圈內不能生產之物，是空間的互補；而以同易同的交換是時間的互補，以某一短暫期間內超量生產的某物，換取其他時間別人生產的同一物。前者是空間的分工，後者就是時間的分工。在雅美社會中每個人或家庭雖都能生產所有必需品，卻不必每日同時從事所有的生產項目，因此有些人力可以從食物生產工作解放出來，以從事其他同樣必須的非產食性工作，或投入儀式慶典、休閒活動中。此種分工在簡單社會中，對自然及人力資源的經濟使用具有重大貢獻，因此以同易同的交換除強固社會關係外，經濟上的功能也不可忽略。希望雅美人的案例對於以同易同式交換的瞭解能夠提供一些啟發。

Exchange in simple societies can be classified into two general types: 'unlike-for-unlike' or 'like-for-like.' 'Unlike-for-unlike' exchange takes place when products produced in one place are exchanged for products produced in other places to meet those needs that cannot be met by local production. In such circumstances exchange of 'unlike-for-unlike' is economically rational insofar as real needs are being satisfied through exchange. 'Like-for-like' exchange, on the other hand, usually takes place where the parties to these exchanges of like-for-like are equally able to produce the needed items without exchange and where the items exchanged neither differ in quantity nor kind. On the surface at least, such exchanged would seem to lack a rational economic utility and would thus seemingly be in support of a nonutilitarian view of exchange. This essay reviews Yami product exchange in daily life, in three major calendric festivals, and in house-opening and boat-launching ceremonies within a single ecological zone to examine the possible economic rationality of 'like-for-like' exchanges. I conclude that the economic rationality of these exchanges is in meeting needs that arrive at different times by moving around production surpluses within the same ecological zone. In Yami society, individuals and families are quite able to meet their own needs through their own production. Still, these needs do not have to be met by daily production. Instead, daily work can be redirected from, say, food production to such other activities as other production, ritual performance, and relaxation. Such a division of labor in simple societies allows for a more rational allocation of natural and human resources. The conclusion is, then, that like-for-like exchanges not only strengthen social relationships, but also serve material needs.