交换、正义与高利贷:托马斯·阿奎那的经济伦理观

Exchange,Justice and Usury:Thomas Aquinas's Economic Ethics

中世纪经济伦理问题由来已久,在12—13世纪尤为突出。13世纪圣托马斯·阿奎那的高利贷论,深度回应了教会对此问题的关切。他认为高利贷合乎人法且具有现实性,但违背自然法和神法而不具有德性;物的用途影响物的属性,以此可解释其为何反对借贷取息而支持租赁获利;其"货币不具增殖性"观点与其不支持"可能利息补偿"的态度贯穿始终;其所指货币购买力对应货币交换价值,而取息问题则对应货币自身价值;其公平价格理论与高利贷学说在赊买赊卖上围绕公平价格标准发生实质性联系;其所指公平正义不惟严格公正,还有大致公正,二者并存。阿奎那的高利贷论虽以基督教伦理为先,但也不乏某种"经济学"因子,因此成为整个经济学说史的组成部分。

Thomas Aquinas's writings on usury reflect the response of the Church to the problem of economic ethics,aproblem which had a long history but which became far much important in the12 th century and especially in the 13 th century.The forms in which Aquinas handles the topic—e.g.his disputationes—serve his economic ethics and are not open-ended.He considers usury to be legal under human law but unjust under divine law/natural law,this being in conformity with his theory of law.He thinks that the property of a thing changes with its use;keeping this in mind enables us to understand better why he sees money lending at interest to be unjust but house leasing and societas just.His argument that money is sterile and his attitude towards compensation for the possible loss of profits are consistent throughout,not contradictory as has hitherto been claimed.The purchasing power of money as he sees it corresponds to the price of the commodity whereas lending money for usura corresponds to the intrinsic value of money;this does not support thescholars'conclusions on this point.In buying and selling on credit,once justum pretiumis introduced,the theory of just price is really linked with the problem of usury,this being what the scholars fail to understand.By'commutative justice'he means not only exact equality but also approximate equality,both of which are presented through his treatises;no clear or even simple linear change in his conception of justice can be seen from one to the other.Aquinas's treatises reflect the Church's teaching but at the same time contain the seeds of economics,in the history of which they constitute an inseparable part.