Let me just ventriloquize a good-faith critic: psychoanalysis cannot demonstrate its claims historically. It has no special means to produce a history of the world, yet it rejects conventional historiography.
I don't see much sense in brushing off that sensible objection.
I don't see much sense in brushing off that sensible objection.
For Freud, in dreams the unconscious is totally self-referential, a closed system, but you wake up in 'reality', the sought after standard of historian and philosopher alike. Lacan rejects this saying language is like the unconscious and like a dream, a totally closed system.
The paradox is obvi: the ideal of reality's measure is a linguistic effect not a measure of illusion against something concrete. Yet, history produces this discursive distinction between illusion and reality. The onus is on psychoanalysis to provide a way to write that history.
That onus on providing that history and accounting for that distinction simply has no bearing if you study literature, but it does if you're a Marxist or if you study history or, in the case of psychoanalysts, if you have a 'flesh and blood' person in front of you.
Psychoanalytic practice can draw upon a specialized experience of the clinic and say, "let's leave the historians and philosophers to their troubles with reality, ours is the domain of fantasy, and our couches produce enough evidence of its oneiric logic."
The problem, of course, is that this is a copout and undercuts Lacan's larger claims about moving, as he so famously put it, "beyond the reality principle."
The last I'll say as a kind of gambit: Lacan's expansion of the primary unconscious phenomena—dreams, slips, and jokes—into the wide array of rhetorical moves and to a study of discursive logic *might* lend itself to a kind of historical writing, but we have no blueprint really.
Tl;dr: What's good for the psychoanalytic critic and analyst is not necessarily good for the historian.