主體間性與婚姻家庭治療兩者都重視關係，強調人們透過溝通、相互理解、形成共識，以解決問題，以及都關心主體性，而後者更以增進來談者主體成熟為主要目標。本文提出「主體力」的構念，它是在生活世界中建構主體性所需的能力，包括「個體力」與「關係力」。本文以案例說明主體間性理念實踐於以增進來談者之「主體力」為目的的婚姻家庭治療所激發出的一些 思考。提出MFT場域是「成長性階層結構」，治療師運用治療權力調發來談者的「個體力」，使其具有溝通理性的能力與態度是第一類進展，而增強來談者的「關係力」，使之有能力與他者發生成長性之互動則是第二類進展。促成個體成長與關係發展，亦即這兩類治療進展的實務經驗，有助於了解人們成長的人際和內在關係歷程。我們希望這些資料，除了可豐富婚姻與家庭治療理論與實務，亦可補充主體間性理論。

Both intersubjectivity and marital & family therapy (MFT) place importance on relationships. Both emphasize problem-solving via communication, mutual understanding, establishing common views, and subjectivity. Moreover, the major goal of MFT is to facilitate the client’s subjective maturity. In this study, the authors discuss the construct of “subjective abilities,” the abilities needed to construct subjectivity in one’s life-world, which is comprised of “individual and relational capabilities.” Furthermore, this article focuses on some insights inspired by applying practical ideas of intersubjectivity to MFT. These insights are illustrated through selective clinical case data. The authors believe that the field of MFT is a “hierarchical structure that promotes mutually growth,” that the therapist makes use of therapeutic powers to enhance the client’s “individual capabilities,” which equips them with the attitude of communicative rationality (termed “Type 1 progress”), and to reinforce the client’s “relational capability,” which empowers them to conduct mutual growth interaction with others (termed “Type 2 progress”). These practical experiences of promoting personal development (Type 1 progress) and relational growth (Type 2 progress) have both contributed to understanding the intra-psychic and interpersonal relational processes of human growth. The authors hope that these findings can both enrich the theory and practice of MFT and supplement the theories of intersubjectivity.