1b. Granted, this is my reality and I’m the only one who can be certain of it (my friend is not certain that I exist; maybe he’s hallucinating me), but the claim “I exist / this is how I see reality” is true. That is, my inner subjectivity is a reality, an existence, something real — and therefore the recognition of my existence is not a recognition of absolute reality? Of reality as such? From which absolute 100% certainty is also derived?

Appendix:

The hair-splitting — a skeptical person, meaning someone who doubts everything and is certain of nothing (that is what he claims), will always say that he is doubtful about every issue. To the question, “Are you certain that you are doubtful, or are you doubtful that you are doubtful and perhaps you are actually certain?” he will answer that he is doubtful. After all, he doubts everything, including doubt itself.
A person, regarding a given subject, is either:
A. Certain.
B. Doubtful.

The skeptic, by definition (if my definition is correct), cannot be certain, so he is always doubtful.
Even if he doubts his skepticism — he has doubted, and therefore he is doubtful.
Doubting skepticism leads back to the point of doubt.
Doubt leads to doubt — always.
So the claim “It is impossible to determine anything with certainty” is either:
A. Certain.
B. Doubtful.

If it is certain, then that is basically saying, “I determine with certainty that nothing can be determined with certainty” — that is not logical.

If it is doubtful, then the person making the claim is in doubt, and that must be so, because even if he doubts that he is in doubt, he returns to the point of doubt (because the act of doubting produces doubt).

Is this hair-splitting correct, logically speaking?

The hair-splitting is neither right nor wrong. It simply doesn’t say anything. That person is doubtful about everything, including the very act of doubting. That’s all. If you ask him whether he is sure that he is doubtful, he can answer no. He is doubtful about that too.

So he is doubtful. That’s exactly the hair-splitting. Why does it say nothing? It says that he cannot doubt the fact that he is doubtful (that is, he is certain that he is doubtful), because the act of doubting is what makes him doubtful. Why does that say nothing?

In addition — what about 1b?

He is doubtful about that too. As for 1b, I answered it, not him. It seems to me we’ve exhausted this.

The questions were asked with mistaken axioms.

After all, it is obvious that if someone has the axiom “I exist,” it cannot be contradicted.

But if someone has a definition of what it means to exist, and then asks whether the “I” fulfills that definition, then he may discover, as a conclusion, that “I do not exist.”

The Rabbi’s answer is not an answer to the question. Because in the question you assumed that “I do not exist” is possible, which contradicts the axiom “I exist.”

And therefore the truth is that the “I” does not exist. But since a person is biased toward himself, and since he sees existence as a virtue, one should not rely on someone who claims that he exists. Those are words that come not from thought but from impulse.

Definition of “exists”:
Exists — is, is present, is found.
When something falls under the category of “existing,” that means it is there, it is present, it has reality.
The question “Do I exist?” means — is there an “I”?
An example, to make it clearer:
“Brave” is a trait. It is something external to a person’s reality.
Therefore there is an “I” separate from the trait “brave,” so one can ask, “Am I brave?”
But “exists” is not an external trait that applies to reality; it is reality itself.
Therefore there is no “I” separate from existence — if “there is an I,” then “I exist,” because “I exist” means “I am,” “there is such a reality that the word ‘I’ describes.”
So the question was whether the Rabbi thinks that his subjective reality, his inner consciousness, his “I,” is reality, that it exists (whether the Rabbi is certain of his very existence), or not, or whether he thinks otherwise.

The principle — at first you presented the concept “exists” as a meaningless concept that first needs to be given meaning (like an unknown or parameter in mathematics, like x) and only then checked to see whether it is present [“But if someone has a definition of what it means to exist, and then asks whether the ‘I’ fulfills that definition…”]. But that is not so, because the word “exists” has a meaning, namely (according to the dictionary): alive, present, current, there is.

Afterward you explained the concept “exists” as some kind of virtue (and a virtue is a title, a trait found in some reality, and it is praiseworthy / gives praise, but it is not the reality to which the virtue is attributed, and in truth it is a concept in its own right that may or may not be present in a given reality) [“and since he sees existence as a virtue”]. That is, there is an “I,” and afterward one must check whether this reality called “I” falls under the category of “existing,” which (according to The Last Decisor) is perceived by people as a virtue.
That too is incorrect, because “exists” is not a virtue or a trait (the difference between a virtue and a trait is that a virtue is a positive trait, whereas a trait is not necessarily positive), but reality itself. Therefore the question is not, “Does the Rabbi attribute to himself the virtue of existence and place himself in the group of existing people?”
but rather (as was already explained), “Does the Rabbi think that the concept ‘I’ is a reality, an existence, something that is there, or not?”

In addition — you cannot determine that “the truth is that the ‘I’ does not exist” when the concept “exists” is a meaningless concept (for you) that first has to be defined and explained what it represents [“But if someone has a definition of what it means to exist, and then asks whether the ‘I’ fulfills that definition, then he may discover that ‘I do not exist’ as a conclusion.”] That is — someone needs to define what the word “exists” means, and only afterward check whether it can be said that he exists.

You completely lost me. You go on at length without explaining anything, and you put words in my mouth that I never said.
If you have some question (I wasn’t able to detect one), formulate it briefly and clearly. Don’t tell me what I said. Ask what you want to ask.
Two remarks from what I did manage to understand here:
1. Existence is not a property. It is a statement about the thing itself, not about its properties. I’ve written that more than once.
2. You do not need to define a concept before using it. As long as it is understood, that is perfectly fine. Otherwise there is no end to it (notice that you did not define “is” and “is found,” yet you used them in defining existence).

Sorry for the lack of clarity. The response was to what “The Last Decisor” wrote.

*The response

Ah, sorry.