Can’t a person be obligated to the Torah without deciding to be part of a public?

He is obligated (and not only can be obligated), because he is part of the public whether he likes it or not. Maybe he just isn’t aware of it.

With respect, Rabbi, Rabbi Shlomo Fischer does mention Rabbi Kook in the context of the nation’s acceptance, in part 2, section 15, p. 110 at the end of note 3 (quoted in From Sinai to the Chamber of Hewn Stone, p. 204 note 403): “And later I found the very basis of this principle of the collective acceptance of the Jewish people upon themselves in the book Adder HaYakar.” And see there on pages 199–205, where they fitted this possibility (that the nation’s acceptance is the source of the validity of rabbinic commandments) into Nachmanides’ comments in the Shorashim.

Indeed. That’s a rare place for him, and even there he mentions the book without the author. Presumably in the hope that the Haredi reader won’t recognize it.

There’s a point here that I’m apparently missing. It’s true that he is factually part of the public, but why does that entail an obligation to accept their understanding? What’s wrong with each individual acting according to his own understanding? Is it because, in the view of the public, that would put him outside the collective (since he would no longer be defined by them as observant)? And if so—so what, if that is his understanding of God’s word?

I hope I’ve made myself clear. I feel the wording is a bit blurry, but I’m unable to understand the source of the obligation here.

It’s like the obligation to obey the law. There are matters in which there is no law, and then everyone can do whatever he wants. But when there is a law, there is an obligation to obey it. Why? Because I am part of the public whose representatives enacted that law, and it is as though I myself enacted it.
So too in Jewish law. In matters where there is no issue with everyone doing whatever he wants, there are no halakhic obligations. But when Jewish law determines something, it apparently does not want everyone to do whatever he wants.

I didn’t understand why, when the generation after the Talmud accepted it upon itself, that obligates me. And likewise, that our ancestors accepted it at the event at Mount Sinai?
What is the definition?
What is the force of “the public’s acceptance”?
I am part of the public only because on important matters we think similarly. So what obligates me?

When the public accepts something upon itself, it obligates everyone included in it. That is the basis of all obligation to state law and to the regulations of guilds and various groups. You are part of the public not because of what you think, but because you are part of it. It’s like being part of a family not because you think like the family. It is simply a fact.

Hello Rabbi,
Can one also say that faith itself—the 13 principles of faith, which are really a positive commandment, “I am the Lord your God”—and the prohibition against entertaining doubts about the principles of faith, which is a prohibition derived from “do not stray after your hearts,” as Maimonides writes in the laws of idolatry—we are obligated to them by virtue of the nation’s acceptance? If so, the answer to the question “Why do I believe?” would be: because it is a commandment. But that would not be a circular argument, because what really obligates me is the nation’s acceptance. In my opinion this is the position of Judaism and its sages, who never investigated faith from the outside, but rather sought to prove that it is true and to refute arguments against it. And so long as there is no absolute proof with no possible answer, we are obligated by the nation’s acceptance.

There’s a logical bug here. There is no formal authority regarding facts, and the principles of faith are facts. Search the site for formal and substantive authority. The positive commandment of faith is itself a far-fetched notion, and you want to build on top of it?! Your guarantor itself needs a guarantor.

The words of Maimonides in the laws of idolatry have been brought on the site several times. I’ll quote them again:

4 Not idolatry alone is it forbidden to turn toward in thought; rather, any thought that causes a person to uproot a fundamental principle of the Torah—we are warned not to bring it to our minds, and not to divert our attention to it and think about it and be drawn after the thoughts of the heart. For a person’s mind is limited, and not all minds can apprehend the truth clearly; and if every person follows the thoughts of his own heart, he will end up destroying the world because of his limited understanding.
5 How so? Sometimes he will explore idolatry; and sometimes he will think about the unity of the Creator: perhaps it is so, perhaps it is not; what is above, what is below, what is before, what is after. And sometimes about prophecy: perhaps it is true, perhaps it is not. And sometimes about the Torah: perhaps it is from Heaven, perhaps it is not. And he does not know the standards by which to judge until he knows the truth clearly, and thus he comes to heresy.

6 Concerning this matter the Torah warned us, as it says, “And do not stray after your hearts and after your eyes, after which you go astray” (Numbers 15:39)—that is, let not each one of you be drawn after his limited understanding and imagine that his thought grasps the truth.

Our Torah is a national, popular Torah; it is not intended only for sages. It was given to the people—to sages and fools, to children and elders. If everyone were to step outside his mental framework and examine all the religions and beliefs and heresies in the world, there would be no Judaism. Rather, the Holy One, blessed be He, used the mechanism of national obligation to bind all generations to all 613 commandments, including the commandments of faith. And when there is a question, it is a commandment to investigate, but one must ask the Rabbi, the great Torah authorities—not ask every question to all the priests and sheikhs and idol worshipers and heretics in the world. That is no way to create a believing nation attached to God. “And I will make you into a great nation, a holy people” was said—not a great religion. In my opinion, that is what preserved Judaism through the generations, together with the intellectual and philosophical reinforcements of the great sages of the generations—Maimonides, Rabbi Yehuda Halevi, and the like—who removed obstacles to faith. But in Judaism, investigation is always a second story built on top of the acceptance of binding faith. In my opinion that is completely legitimate. In the war against Hamas, we do not examine whether perhaps they are right, even though there are such views today. Because every people is obligated to its nation, and one who is not is a traitor to his people. No Russian joined Ukraine in the war. National love is natural. And faith and Torah in Israel are the foundation of our national and historical life. Therefore leaving the Torah is a national crime and a departure from the collective.

On a similar issue, regarding coercing opinions in matters of faith:
Do you know Rabbi Kook’s words?
Letters of Rabbi Kook, letter 20:
Know that straightforward reason is always a great foundation in judgment, both in practical laws and in theoretical ones. Therefore we must always arrive at the center of uprightness, and if you see a contradiction between one truth and another truth, then there must be something decisive here, and this is the place for new learning. Therefore it appears, regarding the halakha of freedom of opinion—which in our time is accepted by most people of the world—to what extent its boundaries reach according to reason. If you should say that it has no boundary, you cannot say that at all. First, because we do not have even one trait in the world whose extreme is not harmful; and second, the nature of the matter requires that there be a limit to freedom of opinion, for if there were no limit at all, and everyone would throw off the yoke of every accepted morality until by his private understanding he arrived at the final view of what he stands for, then the earth would be filled with disgrace. Yet it is also impossible to impose complete restriction on opinions and actions, because actions are necessarily drawn, to a greater or lesser extent, after opinions. So, for example, if a person were to conclude in his heart that there is nothing wrong with murder, this is certainly a sin, because if such an opinion were to spread it would destroy the existence of the world, and so too in similar cases. Thus we learn that there is a boundary to freedom of opinion; the difficult thing is defining that boundary. And it stands to reason that the boundary cannot be exactly the same in every human society. For example, a firm conviction that there is nothing wrong with walking naked in the marketplace—for one who thinks so and argues that people should actually behave that way—is a sin among us, and rightly so, but it is not a sin among the savages on the islands of Guinea, for example. Since there must therefore be differences between one society and another, the difference will not remain fixed in one place, but will vary according to the multiplicity of conditions. And with respect to faith, there is a great difference here between Israel and the nations. If there were any people in the world whose very existence as a people and whose continued existence depended on some particular belief, then there would be full permission—and also an obligation—that with respect to that belief there be no freedom of opinion within it. For this is not freedom, but only laziness in self-defense, for the sake of some tendency toward nervous stimulation among private individuals. True, at times there may be individuals who can rebel against their nation when they find that the belief which unites and sustains their nation is harmful to humanity as a whole; then they would abandon the nation for the sake of truth. But so long as the belief that strengthens their nation is not harmful at all—and all the more so if it is also beneficial beyond its own boundaries, while for the body of the nation it is the foundation of its life—then there is no place whatsoever for tolerance, and one who is tolerant in this deserves inner contempt from the whole nation and from all humanity. Therefore, since there is no other nation in the world for which making known the name of God in the world—as God of the world, keeper of the covenant and kindness, and of all the paths of justice, which are the attributes of the Holy One, blessed be He—is the foundation of its national life and a unique condition of its restoration to its land and the establishment of its government; and since it has such conditions that it cannot exist without these great beliefs; and every greatness of soul is bound up with corresponding deficiencies, and certainly Israel also has such deficiencies that bring it to the necessity of the greatness of bearing God’s name in its collective content—therefore one who causes, by his opinions, and all the more by his actions, weakness in the belief that gives life to the nation is a national criminal, for whom forgiveness is folly. In the whole world we have no parallel to this. The national content of every other nation and tongue in the world is not at all inherently bound up with awareness of God’s name in its midst and in the world, nor with any faith in general. And if there is some isolated nation with a lowly faith, whose faith is national, it is certainly so petty that its spread would itself bring obstacles to all humanity, and especially since it cannot truly endure at all; in that case, that people itself stands destined for destruction, and one cannot demand of its individuals duties toward its preservation. This is the foundation of true zeal for God, whose possessors are worthy that a covenant of eternal priesthood be given to them—in contrast to reckless zealotry that comes from lack of understanding and weakness of strength.