我國民法上的物權法定主義，理論基礎在於 「物權與債權二分」及「所有權絕對」這兩個前提性觀念。隨著這兩個觀念的逐漸相對化，物權法定主義的必要性也開始受到懷疑。事實上支持此一原則的，除了抽象的概念哲學外，還有一些假設，比如物權如果聽由當事人創設，將使社會付出過高公示成本而形成資源浪費，或封建地主將透過複雜的物權設計來維繫法律所要鏟除的封建制度。作者以R.Coase的理論來分析發現：1.物權法定主義無損於經濟處分自由；2.但因所限制的物權自治將透過更複雜的債權安排來彌補，會使社會付出更高的交易成本：3.即使開放物權自治可能增加公示成本，只要把成本充分內部化，並使當事人能藉防險制度保障交易安全，物權自治仍比較有效率；4.英美未採法定主義，並未形成新封建。

　　　　　The principle of numerus clausus in Chinese Civil Code (Sec. 757) is basedon the old conceptional dichotomy of "obligation" and "things", as well as the idea of absolute ownership. Its necessity becomes dubious, with the growing relativeness of both premises. Also the generally accepted explanations, that the limitation avoids intolerably high land registration costs ,or that it helps destroying feudal system, are now open to question. On the basis of Coase Theorem, the author comes to the following conclusions: (1) Numerus clausus dose not hamper freedom of transaction. (2) It does, however, induce higher transaction costs. (3) A legal system without such limitation can be efficient, if costs of publicity (i. e. land registration) are internalized and other institutions of risk avoidance available. (4) Common Law countries have shown no sign of rebirth of feudal system in spite of their tolerance to contractual arrangements of property rights.