背景：為解決醫病雙方因著專業性、角色產生的不對等狀況，自1980年後開始推廣所謂的「醫病共享決策」（Shared Decision Making, SDM），希望藉此協助病人進行最佳醫療方案的抉擇。但如何落實其價值，避免只是形式上的「分享」醫療資訊，而能真實地進行醫病相互理解，以達到「共享」，此為最大考驗。目的：以海德格《存在與時間》中對「此在」（Da-sein）的探討，特別是時間概念的切入點來作為我們補足醫病共享決策中對於如何進行價值觀共享的幫助。方式：本文透過以下三個面向來探討：一、海德格的「存有論差異」進行了什麼樣的轉向。二、海德格「時間性」的把握，對於存有的意義。三、「時間性」在醫病共享決策中的作用與價值。討論與結論：海德格所提出的「人是向死的存有」以及「此在的存有在時間性中找到意義」都使我們在面對醫病共享決策時，醫病雙方更能夠理解對方所提出的資訊和價值取向。病人因著理解死亡的必然性，因此能夠更真實地對此刻的醫療抉擇進行更有意識的籌劃；醫師也因著能夠對於病人時間整全性的把握，理解病人此時的表現與他過去生命的歷史性、未來生命的投擲脫離不了關係，而更能夠進行理解與溝通。

Background: In order to resolve disparities in specialization and roles between clinicians and patients, the so-called “Shared Decision Making (SDM)” model has been promoted since 1980, in hopes of helping patients choose the best medical treatment plan for themselves. However, the greatest challenge for this model lies in how to realize its true value and avoid merely formalistic “sharing” of medical information, and therefore reach a truly mutual understanding between clinicians and patients to achieve the goal of mutual sharing. Purpose: We will use the discussion of Da-sein (existence) in Heidegger’s Being and Time, and start with the concept of time, to make up gaps with the course of Shared Decision Making in terms of how to mutually share values. Methods: Three dimensions are explored in this article, as follows: 1. What is the meaning of Heidegger’s ontological difference. 2. The significance of Heidegger’s account of “Time” for existence. 3. The value and effect of Heidegger’s “Time” issue in Shared Decision Making. Discussion and Conclusion: As we face Shared Decision Making, Heidegger’s concepts of “being-towards-death” and that “Dasein’s Being finds its meaning in temporality” allow clinicians and patients to have a better understanding of the information and value orientations each other provides. Based on an understanding of the inevitability of death, patients can realistically choose medical treatments and make plans consciously at this moment; moreover, because they are able to grasp the patients’ entire temporality, clinicians can also understand that patients’ performance in this moment is inevitably related to their own pasts and futures, which helps clinicians to better understand and communicate.