Identity of Thought

Identity of Thought is a concept Lacan extracts from Freud's Entwurf (Project for a Scientific Psychology) to name the aim of the secondary process — the psychic apparatus's regulated, reality-testing mode of functioning. Whereas the primary process seeks an "identity of perception" (the hallucinated re-finding of the original satisfying object, Das Ding), the secondary process aims instead at an "identity of thought": a provisional, corrective alignment between the interior movement of psychic representations and the external world, achieved not through hallucination but through a "groping forward," a series of rectifying tests that check each step of ideational movement against reality. The secondary process does not simply reproduce a perception; it traverses a chain of signifying steps — mediated by language — and submits each link to comparison and correction. The cry, as Lacan insists in the same passage, is precisely the hinge that converts an interior excitation into a sign legible to the Other, making unconscious need readable through the structure of language. Identity of Thought is therefore the regulative telos of a process already structured linguistically: it is thought's attempt to find its way not by hallucinating the Thing but by testing, revising, and approximating through the signifying chain.

This concept is crucial to Lacan's larger argument in Seminar VII that Freud's metapsychology is not a psychology of motives but an ethics — and implicitly a linguistics. The gap between Identity of Perception (primary-process, hallucinatory, governed by the pleasure principle) and Identity of Thought (secondary-process, reality-testing, governed by the reality principle) is not merely a technical distinction inside the apparatus; it is the very gap in which language, desire, and the ethical subject are constituted. The apparatus is ethical precisely because it is not simply reactive: it must navigate between the lure of the Thing and the necessity of the signifying detour, and it is that navigation — the "groping forward" — that defines the human psychic economy.

This concept appears in jacques-lacan-seminar-7 (p. 40) as part of Lacan's close reading of Freud's Entwurf, situated within the seminar's opening ethical argument. It is positioned in direct contrast to its canonical twin, Identity of Perception: where Identity of Perception names the primary process's hallucinatory re-finding of the original satisfaction (which maps directly onto the gravitational pull of Das Ding — the impossible, prehistoric Thing around which desire perpetually orbits without reaching), Identity of Thought names the secondary process's language-mediated, rectifying detour around that same impossibility. The two concepts together constitute the structural polarity of Freud's apparatus, and it is precisely this polarity that Lacan mobilizes to argue that the unconscious is structured like a Language: the cry that converts excitation into sign is the minimal unit at which secondary-process logic — and therefore the possibility of identity of thought — becomes operative.

Identity of Thought also connects obliquely to Displacement and Metonymy: if displacement is the sliding of cathexis along associative chains (primary process, free mobility), then Identity of Thought names the counter-movement — bound, tested, corrected — that metonymically approximates the Real without ever reaching it. The "groping forward" of the secondary process is, in Lacanian terms, the subject's traversal of the signifying chain under the constraint of reality-testing, held accountable to an external check. Within Seminar VII's argument about the Ethics of Psychoanalysis, Identity of Thought thus marks the psychic locus where the subject is already, structurally, an ethical being: navigating between the lure of the Thing and the necessity of the signifying detour, neither collapsing into hallucination nor ever fully closing the gap with the Real.

Seminar VII · The Ethics of PsychoanalysisJacques Lacan · 1959 (p.40)

what does the secondary process tend toward?... It tends toward an identity of thought. What does that mean? It means that the interior functioning of the psychic apparatus... occurs as a kind of groping forward, a rectifying test

The phrase "groping forward, a rectifying test" is theoretically loaded because it characterizes the secondary process not as a achieved correspondence but as an ongoing, corrective approximation — a movement that is inherently provisional and mediated, contrasting sharply with the immediacy of Identity of Perception. "Rectifying" signals the presence of an external standard (reality, the signifying chain) against which each step of "interior functioning" is measured and adjusted, which is precisely the linguistic and ethical structure Lacan wants to identify inside Freud's apparatus.