‌‌‌‌　　英：dual relation; 法：relation duelle

‌‌‌‌　　二元性与二元关系是想象秩序的基本特征。二元关系的范式，即是拉康在其镜子阶段 (MIRROR STAGE)的概念中加以分析的自我 (EGO)与镜像 (SPECULAR IMAGE)之间 (即a与a'之间)的关系。二元关系始终是以相似性、对称性与互易性的幻象为特征的。

‌‌‌‌　　相较于想象秩序的二元性，象征秩序是以三元组为特征的。在象征秩序中，所有的关系都会涉及三个项，而不是两个项：这个第三项即在所有想象二元关系中起中介作用的大他者。想象二元关系中的互易性幻象与象征界形成了鲜明的对比，后者是“绝对非互易性”(absolute non-reciprocity)的领域 (Ec, 774)。俄狄浦斯情结是三角结构的范式，因为父亲就是作为一个第三项而被引入在母亲与孩子之间的二元关系之中的。从二元关系过渡到三角结构的俄狄浦斯式通路，无非就是从想象秩序过渡到象征秩序的通路。实际上，结构的概念本身即至少包含三个项，“在结构中总是存在着三个项”(S1,218).

‌‌‌‌　　想象二元组与象征三元组之间的对立，由于拉康对于“想象三元组”的讨论 (E, 197: S4,29)而变得复杂化了。想象三元组是拉康在那些不同于纯粹二元关系的方面对前俄狄浦斯阶段（PREOEDIPAL STAGE)加以理论化的尝试，它指涉的是先于俄狄浦斯情结的时刻，即当一个第三项（想象的阳具）循环在母亲与婴儿之间的时候。因此，当父亲介入俄狄浦斯情结的时候，他便可以被看作（介于母亲与孩子之间的）一个第三项，抑或被看作 (除了母亲、孩子与阳具之外的)一个第四项。正是出于这个原因，拉康才写道，在俄狄浦斯情结中“涉及的不是父亲一母亲一孩子的三角关系，而是（父亲）一阳具一母亲一孩子的三角关系”(S3,319).

‌‌‌‌　　拉康对其同时代精神分析理论的最常见的批评之一，就是这些理论始终未能对象征界的角色加以理论化，并因而将精神分析的相遇化约为分析家与分析者之间的一种想象的二元关系。拉康指出，这一错误便是在精神分析理论中产生整个一系列误解的根由所在 (E, 246)。特别是，它把分析治疗还原成一场自我对自我 (ego-to-ego)的相遇，而因为在所有的想象二元关系中所固有的侵凌性，这一自我对自我的相遇往往会退化成分析家与分析者之间的一场“殊死搏斗”，一场令他们在其中“剑拔弩张”的权力斗争 (见：主人[MASTER]).

‌‌‌‌　　拉康反对这样的一种误解，而强调象征界在分析过程中的功能，即它把作为第三项的大他者引入了分析的相遇。“我们必须在三个项而非两个项的关系中来阐明分析的经验”(S1,11)。分析家不应当把治疗看作分析家必须在其中克服病人的阻抗的一种权力斗争一这不是精神分析，而是暗示一相反，他必须认识到自己与病人皆同样受制于一个第三项的力量，即语言本身。

‌‌‌‌　　拉康对于二元性的拒绝，亦可见于他抵制所有二元论的思维图式而赞同三元论的图式，“所有的双边关系都总是会被打上想象界的戳记”(Lacan, 1956b:274)。例如，拉康打破了实在与想象之间的传统二元对立，而提出了实在、想象与象征的三重模型。其他诸如此类的三元图式有：神经症、精神病与性倒错的三种临床结构，自我的三种构形 (自我理想、理想自我与超我)，自然一文化一社会的三元组等。然而，似乎是为了抵消此种倾向，拉康也同样强调了那些包含有四个元素的图式的重要性（见：四元组[QUATERNARY])。

‌‌‌‌　　(relation duelle) Duality and dual relations are essential characteristics of the imaginaryorder. The paradigmatic dual relation is the relation between the EGO and theSPECULAR IMAGE (a and a) which Lacan analyses in his concept of the MIRRORSTAGE. The dual relation is always characterised by illusions of similarity, symmetryand reciprocity.

‌‌‌‌　　In contrast to the duality of the imaginary order, the symbolic order is characterised bytriads. In the symbolic order all relations involve not two but three terms; the third term isthe big Other, which mediates all imaginary dual relations. The illusion of reciprocity inthe imaginary dual relationship contrasts with the symbolic, which is the realm of'absolute non-reciprocity' (Ec, 774). The Oedipus complex is the paradigmatic triangularstructure, since the Father is introduced into the dual relation between mother and childas a third term. The Oedipal passage from a dual relation to a triangular structure is noneother than the passage from the imaginary to the symbolic order. Indeed, the very conceptof structure itself involves a minimum of three terms;'there are always three terms in thestructure' (S1,218).

‌‌‌‌　　The opposition between imaginary dyads and symbolic triads is complicated by Lacan's discussion of the 'imaginary triad' (E, 197; S4,29). The imaginary triad is Lacan's attempt to theorise the PREOEDIPAL STAGE in terms other than those of amerely dual relationship, and refers to the moment preceding the Oedipus complex, whena third element (the imaginary phallus) circulates between the mother and infant. Whenthe father intervenes in the Oedipus complex he can therefore be seen either as a thirdelement (between mother and child) or as a fourth element (in addition to mother, childand phallus). It is for this reason that Lacan writes that in the Oedipus complex'it is not aquestion of a father-mother-child triangle, but of a triangle (father)-phallus-mother-child' (S3,319)

‌‌‌‌　　One of Lacan's most frequent criticisms of the psychoanalytic theory of his day is thatit constantly fails to theorise the role of the symbolic, and thus reduces the psychoanalyticencounter to an imaginary dual relationship between analyst and analysand. Lacan arguesthat this error lies behind a whole series of misunderstandings in psychoanalytic theory (see E, 246). In particular, it reduces analytic treatment to an ego-to-ego encounter which, because of the aggressivity inherent in all imaginary dual relations, often degenerates intoa 'fight to the death'between analyst and analysand, a power struggle in which they areat daggers drawn' (see MASTER).

‌‌‌‌　　Against such a misconception, Lacan insists on the function of the symbolic in theanalytic process, which introduces the Other as the third term in the analytic encounter.'It is within a three-rather than two-term relation that we have to formulate the analyticexperience' (S1,11). Rather than seeing the treatment as a power struggle in which theanalyst must overcome the patient's resistance, which is not psychoanalysis butsuggestion, the analyst must realise that both he and the patient are equally subjected tothe power of a third term: language itself.

‌‌‌‌　　Lacan's rejection of duality can also be seen in his rejection of all dualistic schemes ofthought in favour of triadic schemes;'all two-sided relationships are always stamped withthe style of the imaginary' (Lacan, 1956b:274). For example instead of the traditionalbinary opposition between what is real and what is imaginary, Lacan proposes a tripartitemodel of real, imaginary and symbolic. Other such triadic schemes are the three clinicalstructures of neurosis, psychosis and perversion; the three formations of the ego (ego-ideal, ideal ego and superego); the triad nature-culture-society; etc. However, as if tocounteract this trend, Lacan also emphasised the importance of schemes involving fourelements (see QUATERNARY).