英：mathematics; 法：mathematiques
在其理论化象征界 (SYMBOLIC)范畴的尝试中，拉康采取了两种基本的取径。第一种取径即根据借自语言学 (LINGUISTICS)的术语来对象征界加以描述，也就是运用受索绪尔启发的语言模型将其描述为一个能指系统。第二种取径则是根据借自数学的术语来对其加以描述。此两种方法是互补的，因为两者皆试图以精确规则来描述形式系统，且两者皆示范了能指的效力。尽管在拉康的著作中存在着一个总体上的转变，即从在1950年代居于主导的语言学取径转向在1970年代居于主导的数学取径，但是早在1940年代便已然存在着一些数学取径的痕迹 (诸如拉康对于一则逻辑难题的分析，见：Lacan, 1945: 亦见他在1956年的主张：“主体间性的法则皆是数学式的”，见：Ec, 472)。拉康使用最多的数学分支是代数学 (ALGEBRA)与拓扑学 (TOPOLOGY),尽管也同样存在着一些关于集合论 (set theory)和数论 (number theory)的涉猎 (例如：E, 31618).
拉康对于数学的使用代表着一种旨在将精神分析理论加以形式化的尝试，而这也符合于他的如下观点，即精神分析理论应当渴求科学所特有的那种形式化，“数学式的形式化是我们的目标、我们的理想”(S20,108)。对拉康而言，数学充当着现代科学话语的范式，此一话语“是由数学中的那些小写字母而呈现出来的”（S7,236).
然而，对于数学的这种使用并非是旨在产生一种元语言 (METALANGUAGE)的尝试，因为“没有元语言是可以被言说的”(E, 311)。“这一困难的根源便在于你只能通过使用日常语言来引入那些数学的抑或其他方面的符号，因为你毕竟不得不说明你要用它们来干什么。”(S1,2)因而，拉康对于数学的使用便并非是一种旨在逃离语言歧义性的尝试，而恰恰相反，是旨在产生一种形式化精神分析的方式，使之产生多重的意义效果而不至于被化约为某种单义的意指。同样，通过使用数学，拉康也是在试图防止所有那些旨在对精神分析加以想象性的直觉化理解的意图。
(mathematiques) In his attempt to theorise the category of the SYMBOLIC, Lacanadopts two basic approaches. The first approach is to describe it in terms borrowed fromLINGUISTICS, using a Saussurean-inspired model of language as a system of signifiers. The second approach is to describe it in terms borrowed from mathematics. The twoapproaches are complementary, since both are attempts to describe formal systems withprecise rules, and both demonstrate the power of the signifier. Although there is a general shift in Lacan's work from the linguistic approach which predominates in the 1950s to amathematical approach which predominates in the 1970s, there are traces of themathematical approach as early as the 1940s (such as Lacan's analysis of a logical puzzlein Lacan, 1945; see his 1956 claim that 'the laws of intersubjectivity are mathematical'in Ec, 472). The branches of mathematics which Lacan uses most are ALGEBRA andTOPOLOGY, although there are also incursions into set theory and number theory (e.g.E, 316-18).
Lacan's use of mathematics represents an attempt to formalise psychoanalytic theory, in keeping with his view that psychoanalytic theory should aspire to the formalisationproper to science;'mathematical formalisation is our goal, our ideal' (S20,108). Mathematics serves Lacan as a paradigm of modern scientific discourse, which 'emergedfrom the little letters of mathematics' (S7,236).
However, this use of mathematics is not an attempt to produce a METALANGUAGE, since 'no metalanguage can be spoken' (E, 311).'The root of the difficulty is that youcan only introduce symbols, mathematical or otherwise, by using everyday language, since you have, after all, to explain what you are going to do with them' (S1,2). Thus Lacan's use of mathematics is not an attempt to escape from the ambiguity of language, but, on the contrary, to produce a way of formalising psychoanalysis which producesmultiple effects of sense without being reducible to a univocal signification. Also, byusing mathematics Lacan attempts to prevent all attempts at imaginaryintuitiveunderstanding of psychoanalysis.