But, you know, 'psychoanalysis'...
We currently don't know concretely how psychological phenomena like consciousness, happiness, selfhood, desire are formed or what they consist of. We know they exist, because we experience them 'in normal human experience'.
Analogously, Aristotle did not know anything concrete about how atoms, energy, time, cells in the body worked. But his natural philosophy created a speculative framework to talk about these things, explore possibilities, and try to relate what was known or observed, to what might possibly be true.
The potential advantage of modern theories like psychoanalysis, is that today we are able to make a clear distinction between falsifiable scientific knowledge, and other types of statements about the world. Thus, we can evaluate Lacan's thought on the correct level - as a form of philosophy which gives us a way of thinking about certain matters without attempting to provide definitive information.
Your rather generous interpretation could equally apply to quantum coaching or any other modern fad that is clearly wrong, because even though we don't know everything, it conflicts with what we know.
Psychoanalysis, when tested empirically, produces therapeutic effects no worse than other talking therapies. In fact the great empirical paradox of therapy is that they are all similarly successful, regardless of the exact details of the theory they are based on.
But if that's so, isn't that saying that the theory is irrelevant? And if so, why do I care about Lacan? Okay, so he's got a theory. So do lots of other people, and they all work just as well in practice.
I'm not sure what other "types of thought and culture" you are referring to. A superhero movie certainly is entertaining, can make you think and it's not a scientific theory. However, the big difference is that a movie does not make empirical claims or promises to have access to a method of self-knowledge, nor does it try to explain mental disorders. Psychoanalysis is mainly a service that promises empirical effects, and therefore should be treated empirically. Furthermore, Freud certainly envisioned it as a scientific theory, and so did many of its followers. I just don't think that this defense of psychoanalysis as having some sort of entertainment value, despite its absurdity, is a saving grace.
Your second point only reinforces what I'm saying. If any type of therapy has the same effect, then they are all placebos. Their effect is comparable to homeopathy, which is none. Homeopathy is certainly a different "type of thought", that is, an incorrect one.
Of course, making sense of Lacan is indeed an undertaking, because his work is so discursive ("return to Freud" x Enlightenment x Classical phil) and also in a peculiar seminar medium, so I don't blame people for not wanting to make an attempt, especially since Lacan in particular would require suspending one's axiomatic presuppositions about epistemology and ethics (knowledge and goals), assuming one is mostly familiar with scientific or technical fields of study. Typically in a case like that I would simply say "I don't know enough to say", whereas a judgment of "nonsense" is effectively a signal of faith rather than pure non-comprehension.
What I'm saying is that I applaud your efforts to communicate (and think you're basically correct in your interpretation, although perhaps not phrased in a way that will immediately click with readers here), and wish you luck, but I have a feeling based on experience that it will end in frustration.
They seem to have these common features:
1) They are self-contained systems. They may be interesting in the terms of sci-fi worldbuilding, but you must suppress critical thinking and just absorb them or they fall apart.
2) Experts tend to discuss in the terms of what the founder or important figures meant. Understanding the subject is interpreting what few people said and thought. Right and wrong is about right interpretation.
3) Advance happens by forking or dissolving into smaller groups with different interpretations. There are main divisions, sub divisions, and so on.
I find hard to understand these kind of systems. There may be some initial core ideas that are interesting to ponder, but building whole system seems very limited and dogmatic.
If there is no way to create synthesis or settle questions among experts who disagree, and the only way is to branch, is there anything there?
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edit:
My null hypothesis for the effectiveness of psychoanalysis and psychotherapy in clinical setting is that the theory or method is just a framework that
A) helps analysts and patients that understand and work well together to find each other. Like Trekkie getting into therapy with a Trekkie fan therapist, or a Chatholic patient having therapist with Catholic backround.
B) it gives some needed structure, the theoretical framework itself is not that important.
C) the real help comes from interacting and talking with a person intimately.
In this sense, anything goes as long as it's not outright harmful.