成功的道德教育不能只是教導青年人有效地推理出正確的道德決定或結論，卻無法使他們適當地行動。這種道德意志薄弱現象早在Socrates時代就受到注意，並在當代規約主義的主張中被視為是邏輯上不可能的。本文則認為「道德意志薄弱是邏輯上不可能」的主張必須受到批判地檢視。本文運用哲學思考，旨在指出「道德意志薄弱」不僅是邏輯上可能的，且是關心道德教育者必須面對和努力克服的重要議題。本文逐一討論道德意志薄弱的可能性；指出道德意志薄弱至少可分成同一時間的不一致性規準及能力的規準；分析道德意志薄弱的成因則包含智識上的不誠實及立即性的欲求等兩項因素；並針對這些發生的成因，指出道德教育者可以克服的可能作法。道德教育者的具體作法則是可以引導學習者去省察、檢視或甚至修正自身最想要的欲求；透過道德習慣和榜樣的學習，來取得原則與行動之間的一致；以及運用獎懲、理性的討論、假設的道德情境和道德想像等方式，來減輕立即性因素對於行動者的影響，促使學習者能夠養成道德習慣、涵養德行和能力，使得道德的證立理由和動機理由趨於一致地採取行動，成為克服意志薄弱且知行合一的道德行動者，達成道德教育的最終目的。

Successful moral education not only enables young people to reason effectively and makes correct moral decisions or conclusions, but also lead them to act appropriately. The problem of moral weakness has been noticed since Socrates and treated by modern prescriptivism as logically impossible. This author argues against the claim that the problem of moral weakness is logically impossible, for this problem has considerable significance for the study of theories and practices of moral education.This article first of all discusses the possibility of moral weakness. Then it develops two criteria for identifying the problem of moral weakness. Then it points out two main reasons for this problem. Finally, based on the above discussion and analysis, the author tries to propose some methods to be employed in moral education to rectify or overcome the so-called moral weakness.