Question

Is the trilogy really such a tragedy??
How does one deal with a thin Judaism? And with proposals for changes in Jewish law?
I have to note that I haven’t read Rabbi Dr. Michi Abraham’s new books, but I’m having a hard time understanding the controversy around them or against them.
Any argument about principles of faith, meaning “what one must believe,” is circular.
Why?
If a person denies a principle of faith, then the sides are clear: I believe in the resurrection of the dead, he does not believe, and his status is as explained in the Shulchan Arukh, etc.
If a person claims that one is not obligated to believe in something specific (and also does not believe in it), then according to his view there is no problem at all with his lack of belief. Only according to those who hold that one must believe is there a problem with his belief. But they admit that the problem exists only according to their own view. They claim they are right, but he claims he is right. Problem.
Then Michi comes along and argues that one can dilute some of what the majority considers principles of faith, and that one need not believe in them.
Those who argue against him, that one indeed must believe, rely on sources that in their view it is forbidden to deny. But in Michi’s view it is permitted to deny them. So the argument against him is circular.
In short, when arguing about the source of authority, there is no common denominator, and therefore there is no argument.
You can argue about what someone says if you recognize him as an authoritative source. If you do not recognize him as an authoritative source, there is no way to argue. If one recognizes A as an authoritative source because of B, but the other does not recognize B either, then there is no clash.
In my personal opinion, the question of what one is obligated to believe is a halakhic question. Since, unlike questions of interpretation, outlook, and understanding the ideas of the Torah, which are not Jewish law, someone who denies principles of faith has a halakhic status (as explained in the Shulchan Arukh, etc.), therefore the question “who is an apikores” is a halakhic question.
Granted, even in Jewish law one can argue; every seasoned student is allowed to propose his opinion in Jewish law. And Rabbi Michi Abraham too, as someone who has taught Torah to the public for many years, can propose his opinion in Jewish law.
Presumably, most halakhic decisors will not agree with the rulings on matters of thin Judaism.
But the purpose of this thin Judaism is to allow people who cannot, or simply do not feel like, believing in a “fat” Judaism to remain believing people.
So why should we care?
Most believers are not troubled by some determination that one is not obligated to believe something; the fact that one is not obligated does not mean it is not true. If there is a dispute between Maimonides and the Raavad over whether someone who believes in corporeality is an apikores, that obviously does not mean that we should believe in corporeality, just because according to the Raavad there is “thin Judaism” here. And so too regarding all the other slim-downs: suppose one is not “obligated” to believe in providence at AAA level, and someone who does not believe will not be killed. Does that mean there is no providence or no reason to believe? Whoever thinks one need not believe in it—good for him.
Michi himself also is not going in the direction of Leibowitz, for whom any discussion of anything related to spirituality aroused revulsion, disgust, and contempt and was considered idolatry, and beyond a Spinozist God who hated settlers he was unwilling to accept any other possibility.
Michi says that he does not believe, because he sees no reason to believe. He does not even argue that all the “fat” must not exist, only that he does not feel a need to believe that it must exist. So I say—good health to him.
The same thing regarding changes in Jewish law: if he wants to propose, let him propose. I don’t know whether he means to issue rulings or to suggest. Presumably the majority do not agree. So what difference does it make that someone proposed something and remained in the minority opinion.
Since the dispute in this area is, as stated, circular—a dispute over the source of authority—there is no clash at all.
If someone were arguing for changes in Jewish law and anchored it in the Mishnah Berurah and the Chazon Ish, there would be something to argue about.
If someone were arguing for thin Judaism and anchored it in the Sages, there would be a mess.
But if a person admits that according to accepted halakhic Judaism, there is no room for any part of the trilogy, then all we can do is agree.
And if the halakhic decisors nevertheless become convinced by his rulings, everyone will be happy. In the meantime, that is not the direction.

Continued from the comments

What is there to discuss in his words? He does not accept the tradition (he does not claim that “there is no tradition,” but rather argues that according to the words of the Sages and others, tradition has no authority), and that itself is the issue. In the view of most sages, tradition does have authority, the Sages do have authority, the medieval authorities do have authority, and their words are binding as well. That is why their words are accepted, and not because we have proofs that this is “correct.” Someone who does not want to accept their words, and does not want to accept their words saying that there is an obligation—that is his problem.

Discussion is possible only with a shared basic premise. If someone accepts the Sages or the medieval authorities but claims they meant something else, you can argue with him. If he does not accept the source of authority that I believe in, how can I force him to accept it?