Is it not astonishing that since the world began none of those people who call themselves philosophers dreamt of producing, at least in the classical period, this essential dimension which is the one I spoke to you about under the name of what can be called: autre chose, something other. (Seminar 5, 15.1.1958)
Should there be a coinage, one which could by itself—alone, singly (albeit painstakingly) demarcate the boundaries between Modern Philosophy on the one hand, and Contemporary Philosophy on the other, it must have been the coinage very commonly circulating in ‘post-structuralist’ literatures in Continental thought, namely: the other (at times spelled with a capital letter ‘O’ as in the complex literatures of, but not in any way limited to, Jacques Lacan’s. 
This Other, to be directly broad, pertains to that which eludes any possible identification with the self, or subject (be it singular subject or collective subject, physical or not); this coinage painstakingly dares to capture that somewhat enigmatic and phantasmic something that can never overlap with any cohesive identification whatever—thus the apparently pathetic or weak appeal to merely capitalizing the letter ‘O’ in the efforts to refer to some-thing residing in a dimension that can never be grasped by a consciously ruminative thinking subject.
It is in the preoccupation, interest and business with this obscure other that many elite writers of literatures in Contemporary Philosophy laboured themselves about; and, as pointed by Jacques Lacan (whose return to Freud’s psycho-analysis, at a time when it went marginal, propelled it into radical circulation in France anew) in the exordium above, this something other was virtually lacking in the canon of established philosophers rightful of the title. Thus, with the arrival in Contemporary Philosophy of the painstaking coinage—something other—a kind of intellectual disturbance (very much anticipated by Freud within psychoanalysis in 1916 ) went on to the dismount of the self-aggrandizement which the Cogito (the proverbial faculty about which subjects heretofore purports as the unchallengeable core where Philosophy in general, for example, Descartes’ mantra cogito ergo sum, built itself unshakably) obscenely assumed self-sufficient foundationality—self-sufficient foundationality as if this Cogito is (to borrow language from Michel Foucault’s archaeological deconstructions) a priori ahistorical.
Delving more into this something other, this contrivance is charged with the latently violent subversion of the heretofore alleged potency of the Cogito to absorb, capture and/or understand each and every issue that might accost its way, as well as to retaliatingly defend itself against disturbances as shall unseat it from its dominion. Quite prior to the intrusion by this something other in Contemporary Philosophy, philosophy in general purported to be a deliberate activity of humankind in its cosmic endeavors to know, discern and ascertain that which is out-there, in a manner that is systematically organized, developmental and in the very least logically stable, to the satisfaction of the criterions of human consciousness itself; until finally come said intrusion by this something other, the aforementioned pretenses of the self-consistency of this very concept human subject—not to mention his/her professed claims to ‘consciousness’—began to be exposed, if not as a grossly fleeting construct then as a subverted myth, fantasy, fiction: it being deceptive, narcissistic, delusionary of the paths of ‘the true journey’  .
Lacan’s tutelary return to Freud (under the light of which this paper approaches the Other as a distinguishing trait dividing Contemporary from Modern Philosophy, and as a peculiarity pervasive amongst post-structuralist Continental oeuvres already pointed above) underscores the being decentered of the subject of knowledge—the Cogito—from its erstwhile inimitable posture in the order of beings. A decentering which casts relentless analysis on the processes that structure the notions of truth, meaning and signification alike, but which is unavoidably concealed or neglected—disavowed—by philosophical pretensions issuing from the Cogito itself since it perversely feeds on the very disavowal thereof. Whereas the Cogito believes its self-identity, -centrality or -consistency, or to borrow Lacan’s a phase its ‘illusion of autonomy which it entrusts itself  an illusion which emphatically was a staple among subjects of knowledge from Cartesianism to Existentialism onwards to contemporary Human-ism’s, Lacan’s Freudianism on the other hand, with its affiliation with the term the o-, Other alludes instead to the utter incompleteness and mere apparent coherence and feigned stability of this subject—the Cogito, owing principally to the radical psychoanalytic notion of the Unconscious.
By the terse formulation that ‘the Unconscious is the discourse of the Other  , Lacan stresses the psychoanalytic discovery dating from Freud that very simplistically put: in the pre-symbolic order, man’s preoccupation with language and speech is actually a form of translating a libidinal need into metonymic utterances addressed to something other, who’s distinct from one’s own self, in order that such a pressing need be thereby relieved or alleviated (either by the intro-jection of an object that is pleasurable, or by the pro-jection of the object deemed rather un-pleasurable) as in the case of infantile sexuality (but owing to some certain socio-cultural taboo, this kind of sexual cries because they were deemed perverse are only to be censored and repressed to silence); since these kinds of demands are only to be ever barred by virtue of said taboo/socio-cultural constructs (or by that which in Lacanese is designated as the symbolic Law) but without being completely obliterated, they partake in the production of something new that further dislocates the stability of the prior structure from which it was barred from its free-flow.
This should depict that: there is a constant sliding and shape-shifting of the libidinal flows, to the point of altering the whole structure in which they were silenced/repressed. From the metonymic cries, the metaphoric takes over in the service of these free-flows, especially if the repression at stake occurs in civilization’s symbolic order where linguistic signs or constructs take the place of primal instincts (associated in the prior pre-symbolic order above), and where it will properly be productive of new meanings as shall disturb the alleged constancy and feigned stability of that symbolic structure of language which has been too repressive of them: like in the perverse instincts above, these free-flowing meanings in the symbolic order which though barred, but can only hopelessly be obliterated, remain productive in the Unconscious. Now these irreducible, erratic and constantly irrepresible excesses propel, contradictorily to the assumption that the Cogito is safe an anchorage of thought, the dialectic of the subject as they participate in the production of meaning—disturbing the obstinacy of the symbolic deadlock. Toward emancipation—perhaps—; in the end; as the subject persistently fetishizes that his most honest ruminations might just end up triumphantly, hopefully; in the cortege interim however, a painstaking improvising, a conscious dreaming, floundering fast in our vanity for something other.
 In Ecrits, particularly under “The Freudian Thing,” the uses of the other (lower case) and Other (upper case) is different as Lacan refers to its technical use by analysts during their practice of the disciplining proper. [See: Jacques Lacan. Ecrits, trans. Bruce Fink, New York: Norton, 2006, pp. 357-358].
 Freud after drawing on the naiveté of man before the hands of science and called for the rigorous introspection even against science itself, remarked further: ‘. . . beyond all this we have yet to disturb the peace of this world in still another way, as you will shortly hear. . . .’ [see: Sigmund Freud. Introductory Lectures on Psychoanalysis, ed. James Strachey, London: Norton, 1916, p. 353.]
 Utilizing this very phrase ‘the true journey’, Lacan closes “The Mirror Stage” [see: Jacques Lacan. ‘The Mirror Stage as Formative of the I Function as revealed in Psychoanalytic Experience,’ In Ecrits, trans. Bruce Fink, New York: Norton, 2006, p. 81].
 Ibid., p. 80.
 Ibid., p. 10.