I feel that the Rabbi understood my question better than I understood it myself,
maybe I’ll phrase it differently: how can one prove that a specific psychoanalytic interpretation is accurate?
After all, it isn’t scientific by Popper’s definitions, so how can I know that it is in fact correct?

In my opinion, you can’t. Anyone clear-eyed understands that psychoanalysis is not science in the sense of general knowledge that accumulates and is empirically testable (gives predictions and the like). These are tools that can sometimes help people who are suffering. That’s all. And the proof is the disputes and the different methods, all of which claim the same scientific crown. They all claim they succeed (and most of them with the same degree of lack of justification).
Therefore, in my opinion, one shouldn’t ask whether it’s true, but whether it works (helps). By the way, to the best of my understanding, usually even that (therapeutic success) doesn’t happen. Even when a therapist succeeds at something, it usually happens for one of two reasons: 1. Placebo (the patient’s trust, regardless of what the therapist himself does). 2. Because he has good intuition, with no direct connection to his disciplinary knowledge (which perhaps gives him some general orientation at most, if at all).

So philosophically speaking, is it nonsense, just the psychologist’s subjective feelings?

As far as I know, there are studies (I don’t know how to point to them, hence the reservation) showing that cognitive behavioral therapy (CBT) has more impact than other treatments. Since there doesn’t seem to be a correlation between the treatment method the therapist specialized in and 1 and 2, that would seem to be evidence of therapeutic success.

Yishai, that’s really not agreed upon.
https://en.wikipedia.org/wiki/Cognitive_behavioral_therapy#Criticisms

My question is not about the therapeutic successes of analysis, but about its philosophy.
For example, Freud claims that a child doesn’t want to get out of the bath because it unconsciously reminds him of the warmth and enclosure he experienced in the womb.
Here there are the following underlying assumptions:
A. A person has a part of himself of which he is not aware.
B. The person wants to return to that earlier state of pleasure, which he recalls when he is in water.
In Freud’s view this is a deep experience because it is the first experience on which his whole emotional world is built, the formative impression of infancy.
Conclusion: the reason a person likes being in water is that he wants to return to the womb, and this is the way he does it.
It sounds fairly reasonable.
But how can one “prove” it or “rule it out”?

You could check what happens with fetuses that grew in an incubator—maybe that would have an effect (if unconscious memories are mainly accumulated in the later stages of pregnancy).

Yes, but then we could say that the bath reminds them of the warmth of the incubator. For any proof or disproof of the theory, I’ll have something to say.

Yishai, it seems to me that if CBT succeeds, that is evidence for my point.
Psychoanalysis makes use of theories about the deep structure of the psyche, which is exactly what CBT does not do.
I was careful to write this about psychoanalysis, although in my opinion it is true of most of psychology as well.
Even if there are parts of psychology in which there is success—I assume that is mainly in the area of therapeutic success and not on the level of confirming theoretical knowledge about the psyche. The broad reservation toward psychoanalysis nowadays is also a result of the fact that even a psychologist who believes there are therapeutic successes does not put trust in theories about the structure of the psyche.

I was referring only to therapeutic success, not to the question of the theory.

It wasn’t mentioned here, but Popper’s criteria were stated in relation to psychoanalysis (originally Adler, though he included Freud as well), namely that it is a theory that can explain anything and cannot be refuted, and therefore it is scientific.

Therefore it is not scientific, of course.

Fine, but my question is not whether it is scientific, but whether it is true.

As for the substance of the matter—

It is recommended to read the articles on this issue published on the blog of the scientific skeptic Gilad Diamond, “Sharp Thinking” (and here is a recommendation for an interesting blog, although it is exaggerated and not always accurate).

Itai,
yes, it was mentioned. Not for nothing am I constantly talking about psychoanalysis and not psychology in general (about which I only made a side remark).

Yishai,
even on the question of treatment success, I was talking about the success of psychoanalytic treatment, not psychological treatment in general.