Why? After all, if the Sages enacted ordinances because they thought X had happened, and that was the only reason for the ordinances—if it is proven that X did not happen, then there is no reason at all to keep observing those ordinances, is there?

They enacted them because they thought that was what happened, but the lesson and the insights remain valid even if it didn’t.

A. What lesson exactly remains valid?
B. Why is this different from the prohibition against killing a louse on the Sabbath? The whole reason they ruled that way was based on a mistaken factual assumption, no?

Let me sharpen the question: obviously here there is some message, and it’s not just a meaningless mistake. But at the end of the day, the reason they instituted it was as a memorial to that miracle, and if it didn’t happen, doesn’t that mean this is a mistaken halakhic ruling, like the case of the louse on the Sabbath, even if it has some educational value that is still correct?

There is no connection at all. Suppose they prohibited poultry with milk because they once saw someone get confused and eat meat with milk. Later it turned out that it was soy. Would the ordinance be void? Absolutely not. The concern that one may come to eat meat with milk is real. The mistake was only in the source of inspiration for the prohibition.
By contrast, in the case of a louse there is no permission whatsoever to kill it on the Sabbath. That is a mistake in the prohibition itself, not in the source of inspiration for the prohibition.
With Purim, they established a memorial to God’s miracle, and the lesson is to thank God for His miracles. Suppose the miracle didn’t happen. So what? The lesson still stands (like poultry with milk).

Oh, come on—the childish demagoguery of biblical “criticism” has now reached the one place in Hebrew that I thought had managed to free itself from it.
Of course Purim “didn’t happen” in the same sense that the French Revolution didn’t happen, and just like every other historical event that for some reason is connected to the Jewish people is somehow open to denial, even though everything can be denied.
Is there really anyone left who takes biblical “criticism” seriously? Any historical event can be denied, including the existence of the State of Israel. For example: there are about 2 billion Muslims in the world who completely deny the existence of the state. Just imagine that in another thousand years, if the State of Israel disappears and “scientists” try to reconstruct the local history of the twentieth century CE, based on the majority of surviving sources—the Muslim and pro-“Palestinian” views. The conclusion would be that there is no Israel and no state and not even a Jewish people (see Shlomo Sand and the rest of that nonsense). As a former atheist, I have seen no “proof” against the historical existence of the events of the Scroll of Esther or of any other event in the Torah. Any such “argument” can be applied to any event we are “sure” happened. Recently people have even started casting doubt on Muhammad, the prophet of Islam—and we’re talking about a figure from the seventh century… Which teaches us that anything can be denied according to the logic of “there is no mention of X and no artifact Y and no source Z.” It’s time to get over this German obsession with denying the Hebrew Bible (Tanakh); it’s neither serious nor intellectual.

Rabbi Michi,
I didn’t understand your words.
Suppose the story of the miracle is a folk legend that was passed down through tradition for several generations until it reached the Sages, and they instituted the reading of the Megillah, sending portions each person to his fellow, and gifts to the poor. What is the point of performing these rituals nowadays if the event never happened?
Why should I celebrate an event that never took place?

Because the holiday is not an end in itself but a means of conveying messages and educating. So there is no problem conveying them through a myth. Job never existed and was never created, and yet people still study it. And maybe the same is true of Trumpeldor and his famous saying.

Could this be another good example of the difference between the context of discovery and the context of justification?

In a certain sense.

What exactly is the educational message of Purim? I can only think that the message is that God saves us by miraculous means, and the story of the Megillah serves as a kind of proof of that. If it’s not proof of that, then what is the logic? Do you even think that’s a correct message?

The story of the Megillah is not proof of that but an example of it.
It is a correct message, after an interpretation that is not the place for here.

There are of course many other messages as well, as can be understood from sayings such as “Purim and Esther will not be nullified in the future,” and the like.

And indeed, along these lines the Hasidim were right to say all sorts of “aspects” and the like, as though it is hinted at there, and to say all kinds of little Torah teachings like that—for really everything is there, insofar as it is words of moral teaching and the like. Think carefully about it.

And what if the revelation at Mount Sinai did not happen historically—would that be different with respect to obeying the Sages and their mistakes (or their historical interpretation of it and their message about it)?

With regard to the revelation at Mount Sinai, the situation is different. Without that having happened, how would I know at all what one is required or forbidden to do? You need revelation. See my critique of the book “Was There or Was There Not” here on the site (under Writings – Book Reviews).

If I understand correctly, in the Rabbi’s view the authority of the Sages (as opposed to the Sanhedrin) stems from the consent of the collective. If so, why do we need (historical) revelation in order to obey what they thought was forbidden, for whatever reason it may be?

I am not bound by everything that some group I belong to commits itself to. Does every bit of nonsense my community decides bind me? Within the framework of a discussion about being obligated to what is correct, it matters that my public has committed itself. Without a commanding God, I have no obligation at all—neither moral nor halakhic—and therefore also no obligation to act in accordance with the public’s consent.

Does the very existence of a commanding God derive from the revelation at Mount Sinai? Without revelation—that is, with only a deistic God—are we not obligated to be moral on the basis of reason?

I didn’t understand the question. If you believe in revelation, then presumably there was someone who revealed Himself there, no? So you should ask yourself that, not me. As for morality, again, in my view revelation is not necessary. If I reached the conclusion that God exists and that He expects moral behavior from me, that obligates me even without revelation. It’s just that with regard to Jewish law, I would not arrive at such a conclusion without revelation.

Strange discussion. Why should we care whether the story happened or not? What difference is there between a universe in which the story happened and an identical universe in which the story is only a story? It happened or it didn’t, a very long time ago…
If you are wondering what the lesson and message of the holiday are, then maybe don’t celebrate it? What does that have to do with whether it happened or not? Do we celebrate everything that happened?

You can argue about whether there is a reason to celebrate—Passover, Purim, or whatever—but that has nothing to do with the truth of the event or the parable.