本文從形上學的角度，討論東西方宗教與哲學對於「惡」(evil) 的本質、 根源或起始等問題之不同觀點與相關爭議。 西方哲學與神學中的「惡」(evil)，與「缺乏」(privation) 之概念有關；存有者 (事物或人) 若未符合完滿的狀態或特質，就是缺乏──惡。依此，將「惡」分類為：「形上惡」、「道德惡」、「生理惡」與「自然惡」等四種。中國哲 學對於「惡」的討論，多論究「倫理惡」，對於「惡」的根源，直從人性而作探索，重視揚善去惡的實踐方法。而西方神學與哲學，因為追究「惡」的起始，故產生了「形上惡」與 (本諸上帝信仰而有的) 種種「惡的問題」之豐富論述。 佛家哲學論「惡」，也以「倫理惡」為主。煩惱與惡業都是惡法，更在善與惡的範疇之外，建立非善非惡的「無記」法。善、惡因可導致樂、苦果；心理與行為有善、惡、無記之三類，果報則唯屬無記。西哲將「道德、惡」所造成的惡劣後果視同為惡──「生理惡」與「自然惡」，佛家則將其歸屬於「無記」，不名為「惡」而但名為「苦」。欲離苦必須除惡，故惡與苦依然有密切關聯。 佛法重視經驗法則，故教人於現實狀況中，對「惡」加以觀察，並斷除之，因此沒有「形上惡」(惡之起始) 方面的揣想與論述。較為特殊的是如來藏學說，因其安立原初內在之淨性 (形上之善)，故於惡之起源，則歸諸時間上「無始」之無明，以及外染的「客塵」煩惱。

In this article, I compare different opinions and controversies between Eastern and Western religions and their philosophies on both the essence and the origin of evil. In western philosophy and theology, evil is regarded as being related to the concept privation. They declare that its existence (either something or somebody) is privative when not perfect. Accordingly, it divides evil into four groups: metaphysical evil, moral evil, physical evil and natural evil. On the other hand, Chinese philosophers are more concerned with ethical evil. Since they explore the origin of evil directly from humanity, they pay much attention to a practical method about how to propagate good and discard evil. In Western theology and philosophy, the search to find the origin of evil implies that there exists metaphysical evil. Meanwhile, with faith in God, many arguments arise regarding the problem of evil. In Buddhist philosophy, whenever speaking of evil, they also give emphasis to ethical evil. Both kleca and akucala-karma are evil. Besides good and evil, they establish avyakr, which is neither good nor evil. Good deeds lead to happiness; evil deeds lead to torture. The causes (mental and physical deeds) are divided into three groups: good, evil and avyakrta. Yet, the effect belongs to avyakrta only. Moreover, western philosophers regard bad effects arising from moral evil as evil (physical evil and natural evil), but Buddhists regard them as avyakrta, not evil, but torture. If we want to get away from torture, we have to discard evil deeds. In this sense, evil and torture are still closely related. Buddhists emphasize the Experience Principle. They observe evil deeds during practical life, and then discard them. Accordingly, they have no imagination or arguments about metaphysical evil (the origin of evil). But the Tathagata-garbha School is unique. It is convinced that there exists an original inner pure essence (the metaphysical good), so it regards the origin of evil as the unenlightenment, with no primal ignorance, and as the foreign atom kleca.