人類社會是一個互助的社會，主要方式有互助組織（含商業保險）、社會救助與社會保險三種型態，社會救助與社會保險二者共同組合成社會福利，是政府積極介入的項目。社會保險的發展最晚，卻是目前已開發國家社會互助體系的核心，但沒有標準內容，每一個國家因不同政治、社會經濟背景與價值觀念而產生不同的制度型態。以社會救助及商業保險為兩端，拉出來的居間的連續光譜都可稱為社會保險；這樣的定義雖然明顯，但反映其多樣化的特性。臺灣社會保險制度之規定可不用拘泥於特定的定義上，重點是建立一個符合既有社會背景與未來社會變遷的制度。社會保險建立的目的是取代社會救助，將事後的經濟轉變為事前的預防，其內容既然容許高度的彈性，則未來可致力於規劃一個完整的社會保險（社會安全）體系，逐漸取代社會救助。社會安全網是由社會福利與民間互助組織共同組成，政府若規劃一個規模較小的社會福利體系，則應致力於活絡民間互助組織。

Social insurance was initiated a little more than one hundred years ago, during the course of century it has become one of the most important risk aversion programs in the human societies. Though in general the social insurance has prevailed, practices varied among the developed as well as the developing countries. Anything in between the social assistance on the one side and the commercial, private insurance on the other may be defined as social insurance. The situation reflects the complexity and flexibility of the social insurance programs. This paper proposes a framework of mutual helps in three categories: First, the private cooperative organizations, including benefit societies and private insurance, constitute an open-ended category; secondly the social insurance, a category expandable by squeezing the social assistance; and thirdly the social assistance, a category of last resort which could be minimized but not avoidable. Social insurance and private cooperative organizations are both competitive and reciprocal at the same time. Governments may either pursue to enhance the social insurance programs or stimulate the development of private cooperative organizations.