「不忍人之心」是孟子哲學思想的核心,因爲孟子以「不忍人之心」之有無來定人禽之異,「不忍人之心」是一切道德的根源,是人之爲人的本質。在〈公孫丑上〉「孺子將入於井章」中,孟子藉著「孺子將入於井」一個例子,指出「人皆有不忍人之心」,由此而闡釋惻隱之心、羞惡之心、辭讓之心、是非之心乃仁義禮智四德的根本。本文旨在分析「不忍人之心」的性質,及其與「羞惡之心」、「辭讓之心」、「恭敬之心」、「是非之心」的關係。孟子認爲惻隱、羞惡、辭讓、是非之心,皆源於「不藝人之心」,四心其實就是同一個「不忍人之心」,只是當人面對不同的事情,其心之不忍有不同的表現而已。人不忍無辜者遭遇不測,因爲人有「怵惕惻隱之心」;人不忍人格尊嚴受損害,因爲人有「羞惡之心」和「辭讓之心」;人不忍是非不分,因爲人有「是非之心」。這四心正是仁、義、禮、智四德的根本,所以「不忍人之心」是四德的總源頭。
The mind of compassion is a very importance concept in Mencius' moral theory. It is the mind which manifests itself as the compassionate feeling towards others' sufferings and what distinguish men from beasts. It is the origin of morality, what makes man human. With the famous illustration of an innocent child falling into a well (Mencius: 3A: 6), Mencius argues that every human being is born with such a mind of compassion. He then ramifies the manifestation into the mind of commiseration, the mind of shame, the mind of courtesy and the mind of right and wrong. They constitute the four cardinal principles or virtues of yen, yi, li and chi.However, as the four are but manifestation of the mind of compassion upon different occasions, they are in fact the same one mind. This paper analyses the nature of the mind of compassion and its relation with the four minds.