In the book “Truth and Not Stable” you argued that relying on intuition is an essential part of learning about the world. Aren’t existential experiences included in this category? (It seems to me that one can rely on such experiences, especially when many people undergo the same experience.)

That’s not what I call existentialism. Every philosophical doctrine begins with initial intuitions from which the axioms are formed. Existentialism is closer to experiences and psychology.

I still can’t quite understand the difference… In the context of faith, for example: if a person directly experiences the world, say, and from that starts with the assumption that such-and-such an external world exists—and then by a logical process derives from the existence of this world the existence of God—why is his philosophical move more credible than that of a person who directly experiences God Himself? (And from that experience he can infer, for example, that God exists, that He demands something of him, or that He loves him, depending on the nature of the experience.)

There is no difference. The question is whether we are talking about an experience or a cognition. If it is an experience, that is existentialism, and it has no significance on the factual plane. If it is a cognition or an intuitive insight, then it is not existentialism, and in both cases that is perfectly fine.

So if I understood correctly, I can divide existentialist thought into descriptions of experiences and descriptions of “cognitions”:
That is, if the thinker describes an experience of loneliness or an experience of absurdity, for example, that has no connection to philosophy, since philosophy by definition deals with the world outside the person and not with the person himself(?). Such experiences belong more to the field of psychology.
By contrast, if the thinker describes something like his experience with things outside himself—like God—he can derive from that insights about God (say, that God is greater than he is, or that He demands something of him), and then the thinker and whoever identifies with his feelings will be able to treat this information as valid on the factual plane, because they arrived at it as a cognition of the world (and that is what is called philosophy).

But even from analyzing the first type (a person’s experiences), one can draw conclusions about the person himself and perhaps also about the world, no? (If a person feels moral obligation, something that existentialism deals with, he can develop philosophical conclusions about good and evil or the existence of a commanding authority.)

Precisely. In my book Truth and Not Stable (see a bit in the fourth notebook here), I explained that to “feel” moral obligation means cognition, not experience.

Sorry for going on about this, but now I’m a bit confused… At first you said that existentialism usually lacks philosophical value, but in the end you said that from the “cognitions” described by existentialist thinkers one can draw philosophical conclusions on the factual plane, and that sometimes even the experiences they describe are actually cognitions, as in the case of ethical feelings.

I’ll explain one more time, because we’ve exhausted this. When there are basic cognitions grounded in intuition, philosophical conclusions can be drawn from them. That is not existentialism, since every philosophy is built that way. But experiences that lead to psychological insights are not philosophy.