「他人的存在（the existence of others）」並非哲學史上的老問題，但在胡塞爾（Husserl）將之哲學化地顯題以後，現象學直至近代人文科學，幾乎沒有人可以小看這個問題。繼胡塞爾和海德格（Heidegger）之後，沙特（Sartre）的早期著作《存在與虛無》（L’être et le néant）又為「他人的存在」添了新的轉折。他深感現象學在該問題上遠較其他學統有力，但早期現象學家──胡塞爾、海德格──不是使「他人」擱淺於經驗對象的不在場（absence），就是使「人們」混入世界的抽象存有（Being）當中。相較於始終到達不了具體他人的存在的前輩，沙特所謂的他者（Other） 是在經驗領域內直接相關於我、又有別於我的另一主體。他以笛卡爾式（Cartesian）的我思（cogito）為原型，受黑格爾（Hegel）的自我意識（self-consciousness）觀所啟發，加上對「我」被看（being seen）的第一人稱現象學分析，便揭露此一事實：凡給定「我思，我在」之我在，對「我」而言，便不可能沒有他人存在。當我在被看之際不安地體驗（erleben）諸如羞恥（Shame）、恐懼（Fear）等等情感，它們對於被看之我就是他人存在的明證（evidence）。我是藉此體會或理解他人與我一併存在，或者更精確地說，是我對他存在（being-for-Other），而非我認識或把握另一人作為特定對象的存在，亦非我藉由開展世界間接迂迴地和匿名人們同在（Mit-Sein/ being-with）。除了揭露我的對他存在，羞恥和恐懼等等體驗也是情感地觸發我進一步建構複數他人（others）的具體動機（motivation），因為我得藉由賦予他者對象性（object-ness）以贖回落入他者眼中的異化（alienated）之我。然而，當沙特將我對他存在的體驗一味詮釋為意識主體該去超越克服的異化，那最關乎自我異化的體驗──羞恥，其實並非稱職的建構動機。就算它可以是稱職的動機，體驗也可以不是稱職的負面情感。就此觀之，沙特將我對他者存在的體驗滑轉為能夠且必然觸發建構他人的情感動機，這個過渡不乏勉強偏執之處。筆者認為這不僅僅是沙特的個人癖好所致，更是黑格爾的意識觀對其影響甚鉅、令他未能堅守自身洞見的表現。不過，撇開其建構他人的野心，光就揭露我對他存在的事實而言，沙特在哲學上已經有他的貢獻。

“The existence of others” is not an old theme in the history of philosophy. After Husserl thematized it, however, from the phenomenology he proposed to late humanities and social sciences, this topic can be hardly ignored. After Husserl and Heidegger, Sartre adds a new aspect to “the existence of others” in his early work Being and Nothingness (L’être et le néant). He considers phenomenology as much more powerful than other traditions on this topic. But the former phenomenologists – Husserl and Heidegger – either made “the other” stranded on the absence of an empirical object, or mixed “others” into the abstract Being of the world. Compared to the predecessors who couldn’t reach the existence of concrete others, Sartre’s so-called “the Other” is another subject in my empirical sphere who is directly relating my-self and also other than me. With the Cartesian cogito as a prototype, inspired by Hegel’s idea of self-consciousness, exemplifying “my” being-seen as the case of a first person perspective phenomenological analysis, Sartre successfully discloses the fact that given “I exist” in “cogito, ergo sum”, the inexistence of others is impossible for me. While I uneasily feel like ashamed and scared during my being seen, the Erlebnis such as Shame and Fear is just the evidence of the existence of others for the being-looked-at me. It is through that I apprehend or understand the other’s being-in-a-pair-with-me. To be more specific, it is neither knowledge nor a grasp of the particular existence of another as an object, nor the indirect and oblique “being-with” anonymous others by unfolding the world. It is my being-for-Other revealed through my very own Erlebnis. Besides, the Erlebnis like Shame and Fear are also concrete motivations to affectively effect further constitutions of other individuals, because my self-alienation caused by the look of the Other requires redemption by conferring the Other object-ness. When Sartre interprets the Erlebnis into self-alienation which is to be surpassed or overcome by the consciousness of a subject, however, Shame, concerning the alienation the most, is actually not an adequate motivation. Even if it could be, the Erlebnis can still be inadequate non-negative affections. Given all that, the transfer from the Erlebnis to the affective motivations which can and must effect the constitutions of others is reluctant and paranoid to some degrees. I believe that it is not only a contingent result of Sartre’s personal inclinations, but it also shows that Hegel has such a great influence on Sartre that he cannot always hold on to his own insight. Aside from the ambition to constitute others, however, the mere fact of our being-for-Other Sartre has disclosed is already a contribution to philosophy.

I. 原典（含譯本）
A. Sartre
Sartre, Jean Paul (1943). L’être et le néant: Essai d’ontologie phénoménologique. Paris: Éditions Gallimard.
Sartre, Jean Paul (1943). Being and Nothingness. Translated and Introduced by Barnes, Hazel E. (1966). New York: Washington Square Press.
讓•保羅•薩特（1937）。 《自我的超越性》。杜小真譯（2005）。北京：商務印書館。

B. 其他作者
Descartes, René (1641). Meditations on the First Philosophy. Translated by Cottingham, John (1996). Cambridge: Cambridge University Press.
Heidegger, Martin (1927). Being and Time. Translated by Macquarrie, John and Robinson, Edward (1962). New York: Harper Collins Publishers.
Husserl, Edmund (1931). Cartesian Meditations. Translated by Cairns, Dorion (1973). The Haque, Netherlands: Martinus Nijhoff.
Merleau-Ponty, Maurice (1964). Le visible et l’invisible. Paris: Éditions Gallimard.
笛卡兒（1641）。《沈思錄》。黎惟東譯（2004）。臺北：志文。
莫理斯•梅洛－龐蒂（1964）。 《可見的與不可見的》。羅國祥譯（2008）。北京：商務印書館。

II. 相關研究
Catalano, Joseph S. (1980). A Commentary on Jean-Paul Sartre's "Being and Nothingness". Chicago: The University of Chicago Press.
Desan, Wilfrid (1960). The Tragic Finale: An Essay on the Philosophy of Jean-Paul Sartre. New York: Harper Torchbook.
Hartmann, Klaus (1966). Sartre’s Ontology. Evanston: Northwestern University Press.
Smith, A. D. (2003). Husserl and the Cartesian Meditations. London: Routledge.
德穆•莫倫（1999）。《現象學導論》。蔡錚雲譯（2005）。臺北：國立編譯館。
勞思光（1959）。《存在主義哲學新編》。劉國英．張燦輝編（2001）。香港：香港中文大學。
游淙祺（2005）。〈衝突的人際關係：沙特論「為他人存有」〉。收錄於《現象學與人文科學04：沙特：存在與辯證思維》。劉國英．張燦輝編（2011）。臺北：漫遊者文化出版：大雁出版基地。