A Graphical Treatment of the Coinsurance Clause
针对共保条款难以理解的问题，提出用图形工具解释其核心概念、理论必要性及主要特征，帮助保险从业者、学生及投保人直观掌握。
coinsurance clause is one of the most difficult clauses to understand in the insurance business. For an insurance coverage where the insurer's liability for a loss may be less than the face amount of the policy, theoretically a need exists for coinsurance or some other equivalent arrangement such as graded premium rates. Without coinsurance, a premium rate that is applied uniformly to the amount insured would be inadequate for the insurer and inequibable for the insureds when the latter are allowed to select the amount insured. Coinsurance is widely practiced in property insurance and yet there is much confusion about the concept. This confusion has been attributed to the lack of proper explanation of the subject. Thus says Head, The author believes that much of the current confusion and ignorance about coinsurance and about the problem of insurance to value to which coinsurance is one solution is due to the absence of a firm anatytical foundation for the largely superficial treatment of these subjects in current insurance literature. (See [2], p. 2.) Later, when Head explains the central concept of the need of coinsurance, he uses, however, mathematical formulas with summation of terms involving probabilities and also integral algebra. Is the concept of coinsurance really so difficult that it has to be explained with esoteric mathematics beyond the ken of most of the not so numerate insureds, insurance agents and brokers, and insurance students? Is it not possible to explain the idea more simply so that a large section of the population concerned with it is able to understand the concept? This paper presents a graphical device for explaining the underlying concept of coinsurance, its theoretical necsssity, and some of its salient proper-