本文利用唐代所湧現以命定為主題的小說為探針，重新檢視這中國文化裏特有的人生解釋，欲擘畫出當時所謂「人生命定」的完整概念。已見唐人雖接續漢時已形成的「三命」說，惟置入天庭、冥府的官僚體系以求更具體地施行天意，且又僅強調其中「本命」一項，削弱「遭命」、「隨命」的影響。這樣的轉變，實受唐代民間信仰的影響，另外與當時視天為一切價值根源的概念攸關。如此已令個人命運的操作具有強烈獨立、以及不容許質疑與挑戰的特質，使得已被上天預定的本命，近於無法更動；正因著人格天的意志並無轉寰的空間，必然和善惡有報的報應觀念與輪迴流傳的佛教理論產生了對立。惟面對佛教的盛興，唐代的命定觀已部份承認「三世」報應裏需經輪迴的「生報」與「後報」，不過轉化成上天決定個人今生命運的參考，以因應輪迴思想已深植人心的既成事實，但在本質上仍無改變；對個人生命的看法，乃將人生看待成一連串個別事件的經歷，至於其本質則解釋為民生物資耗用的過程，這樣的設計，可利於證明天命皆已精確而全然的施行。這樣難於改變且近於消極的人生觀點，成為後世命定小說甚而命定觀的共同特色。

This paper used stories of predestination of the Tang Dynasty to re-evaluate the characteristic philosophy of life in Chinese culture, in order to illustrate the concept of predestinarianism of the Tang Dynasty. Although people of the Tang Dynasty continued to accept the “Three Destinies” of the Han Dynasty, the bureaucratic system of Heaven and Hell took over the execution of fate by emphasizing the “Inherited Destiny” and weakening the influence of “Morality-based Destiny” and “Circumstance-based Destiny”. This change not only influenced by the religious belief of the people of the Tang Dynasty, it also related to the concept that heaven was the source of all values. It allowed the strong independence of individual fate that could not be questioned nor challenged. Therefore, the inherited destiny set by the Heaven almost could not be changed. Because there was no room for changes in the will of the anthropomorphized Heaven, it was inevitably in opposition to the retribution concept of good and bad deeds and the transmigration in Buddhism. Facing the flourishing of Buddhism and the fact that the retribution concept already rooted in the mind of people, the predestinarianism of the Tang Dynasty partially acknowledged that in “the Three Periods” retribution, the transmigration must go through “Present Life Retribution” and “Next Life Retribution”, in reference to the determination of a person’s destiny by the Heaven, yet without changing its essential characteristics. As to the view of individual life, the course of life was treated as a sequence of events and the essence of life was the process of consumption in life materials. This was to evaluate the execution and accuracy of the will of Heaven. Such a pessimistic philosophy of life with little changes became the common characteristics of the predestinarianism or stories of predestination of the later era.