user12857: (English is not my mother tongue, sorry in advance if I make mistakes)
I recently read Thanissaro Bhikkhu's writings [1] [2] on anatta and although I found his arguments persuasive I am still conflicted.
I invite you to read them at least in part before reacting as they are rich in arguments and answers to the first objections that might come to mind.
Nevertheless, I quote TB's summary of his thesis and the objections he encountered:

These reflections were sparked recently by reading a critique of an article I wrote in 1993, called “The Not-self Strategy.” The thesis of that article (available in the essay collection Noble & True)—which I revised in 2013 both to tighten and to expand the presentation—was that the Buddha intended his teaching on not-self (anattā), not as an answer to the metaphysical/ontological question, “Is there a self?” but as a strategy for cutting through clinging to the five aggregates and so to put an end to suffering. The main argument I presented in support of this thesis in both versions of the article was that the one time the Buddha was asked point-blank, “Is there a self?”… “Is there no self?” he remained silent (SN 44.10). Similarly, in MN 2, he stated that such questions as “Do I exist?” “Do I not exist?” and “What am I?” are not worthy of attention because they lead to conclusions that fetter a person in a “thicket of views” and a “fetter of views,” including the views that “I have a self” and “I have no self.” In other words, any attempt to answer these questions constituted a side road away from the path of right practice.
The critique—“Anattā as Strategy and Ontology,” written by Ven. Bhikkhu Bodhi—was brought to my attention just over a month ago, even though it has apparently been around for some time. It takes issue both with the thesis and with the argument of my article, but in doing so it displays the scholarly bias mentioned above: that the practice of the Buddha’s teachings is primarily a process of leading the meditator to give full assent to the accuracy of those teachings as a description of reality, and that this assent is what frees the mind from suffering. Because this bias is not only the bias of the critique, but of so much thought in the Buddhist world, I thought it might be useful to explore how both the thesis of the critique and the arguments used in support of that thesis display this bias, so that it can be recognized for what it is not only in this case but also in other Buddhist writings.

I came across this page where Buddhists are debating the view of TB in opposition to Bhikkhu Bodhi's response. In particular, I found this answer interesting.
I'd like to hear your views on the arguments on both sides. Anatta: only a strategy for realization or a real "ontological" position?
Among the trilakkhanas, anatta is really the one I have the most trouble with. I can't understand it. And the more I learn about it, the more I realize that Buddhists don't seem to understand it either, given all the disagreements on the subject. Even within Theravada, many ajahn of the Thai Forest Tradition seem to reintroduce a form of self by talking about the "mind that does not disappear, immutable and indestructible reality" (which clearly resembles the Hindu atman / purusha). Ajahn Maha Bua, considered by his peers to be an arhat, stated that he "observes the essential enduring truth of the sentient being as constituted of the indestructible reality of the citta (heart/mind), which is characterized by the attribute of Awareness or Knowingness. This citta, which is intrinsically bright, clear, and Aware, gets superficially tangled up in samsara but ultimately cannot be destroyed by any samsaric phenomenon.".
In the Mahayana it's even more obvious, we could talk about tathāgatagarbha, buddhadhātu, dharmakāya, dharmadhatu...
Absolutely all these concepts seem to me to be reinsertions through the window of the self thrown out the door. They all affirm, in one form or another, an ultimate reality, which they call "awareness" or "mind", a state of bliss… wich literally corresponds to the Hindu definition of the supreme self.
Yet the Buddha seems to speak explicitly of this state and describe it as just a step towards the summit:

Furthermore, a mendicant—ignoring the perception of earth and the perception of the dimension of infinite space—focuses on the oneness dependent on the perception of the dimension of infinite consciousness. (…)
 https://suttacentral.net/mn121/en/sujato

Even vacuity (sūnyatā) does not seem to be the destination, the infinite nothingness being only a penultimate stage of the jhanas.
What should we think about all this? At the end of the day, it seems to me that the subject can be summed up in one question:
It is often said that the Buddha would have affirmed that all phenomena are without self: sabbe dhamma anatta
Then the question arises as to whether Nibbana is a phenomenon (dhamma) or not. If this is not the case, as some people maintain, it is logical to consider that the supreme reality, being neither impermanent nor dukkha, does not possess the third seal of the no(t)-self either, and to start talking about this supreme mind, awareness, etc., which is not a dhamma, but a permanent and blissful source of all impermanent and unsatisfactory phenomena - by the way, how better to define the phenomenon than as what appears in consciousness? -; in this case, the border with the Hindu atman-brahman becomes extremely thin, not to say non-existent. If, on the contrary, Nibbana is also a phenomenon (dhamma), having no self, the difference with Hindu thought remains but then, what about the other two seals of all phenomena: anicca and dukkha? How to apply them to Nibbana?
Maybe, like dukkha and anicca, anatta must be abandoned once the destination is reached.

user13375: I'd like to hear your views on the arguments on both sides. Anatta: only a strategy for realization or a real "ontological" position?
It is both. 
It is a fact that the direct realization of emptiness is the true antidote to all that ails us in samsara. As such, we must not minimize the importance of annata - it's true understanding and direct realization of it - as the ultimate way to fulfill the soteriological aims of the Dharma. There is no substitute. Only a full and complete and direct realization of anatta will accomplish our aims.
On the other hand, the emptiness of all phenomena - and its flip side dependent arising - is the ultimate truth. If is the supreme fact of existence. I would not describe it as 'a real ontological position' but if I can infer what you are after with those words... then I'd say, yes, more or less that is what you arrive at or at least it is a necessary step on the path to a direct realization.
Often times, people who don't understand anatta or are confused by it - even at a correct, but limited intellectual/conceptual level - fall back to the thicket of views sutta. But this is sour grapes. And rightly so. This is dangerous stuff. But there is a correct intellectual and conceptual understanding of anatta and it is extremely hard to arrive at and it is by no means sufficient to stop at this level. It is absolutely necessary to arrive at this level - a correct conceptual/intellectual understanding - before proceeding to a direct realization. 
The truth is that most lowly beings are not even close to a correct conceptual understanding of anatta and that trying too hard to reach this level can be dangerous to them. That is why the Buddha gave the thicket of views admonition and was silent. He was dealing with an audience that simply was not ready to go further. They did not have the requisite merit to proceed and had they done so at that time they would have harmed themselves. So the Buddha was compassionately telling them what they needed at that time to prevent them from harming themselves.
What people don't understand is that a correct understanding of annata - while absolutely necessary to completing the soteriological goals of the lowly beings - is also extremely dangerous thing to wrestle with. It is a snake that incorrectly grasped will bite and send beings into the lowest of hell worlds, but correctly grasped can be used to extract venom that can be turned into the ultimate medicine. If incorrectly grasped, people will fall to extreme views of annihilationism or eternalism which will wreck their practice and decimate the stores of merit they have built up.
Understanding annata is hard and it is extremely dangerous and it is absolutely necessary and indispensable to achieving the aims of the Buddha for all of us beings. That is why it is so important to have good self assessment for both teachers and students and to understand the risks and rewards. This is dangerous and delicate business. Guard rails are present and are in the suttas and people should heed those warnings and use those guard rails lest they fall into ruin.

user471: I'd like to hear your views on the arguments on both sides. Anatta: only a strategy for realization or a real "ontological" position?
It is both.
From Sutta Nipata 4.14:

Seeing in what way is a monk unbound,
  clinging to nothing in the world?"
  "He should put an entire stop
  to the root of objectification-classifications:
  'I am the thinker.'

This answer talks about a strategy for freedom from suffering, but it also offers an ontological position concerning the self. "I am the thinker" is the hint.
The self is simply a mental idea, a thought, a view. It's an impermanent thought that arises and ceases from time to time.
With the self mental idea as reference, one objectifies and classifies (or reifies) everything else as non-self things. That's papanca. This answer connects self and reification to craving and suffering. This question connects Theravada emptiness to Mahayana emptiness.
It may be argued that apart from the mental idea of the self, there is some other self, that is the True Self.
For this, the answer comes in 2 suttas. The first is the SN 35.23:

“And what, bhikkhus, is the all? The eye and forms, the ear and
  sounds, the nose and odours, the tongue and tastes, the body and
  tactile objects, the mind and mental phenomena. This is called the
  all.
“If anyone, bhikkhus, should speak thus: ‘Having rejected this all, I
  shall make known another all’—that would be a mere empty boast on his
  part. If he were questioned he would not be able to reply and,
  further, he would meet with vexation. For what reason? Because,
  bhikkhus, that would not be within his domain.”

If there is something that is the True Self, it must be within the range of The All.
And then from SN 35.83:

“It is, Ānanda, because it is empty of self and of what belongs to
  self that it is said, ‘Empty is the world.’ And what is empty of self
  and of what belongs to self? The eye, Ānanda, is empty of self and of
  what belongs to self. Forms are empty of self and of what belongs to
  self. Eye-consciousness is empty of self and of what belongs to self.
  Eye-contact is empty of self and of what belongs to self…. Whatever
  feeling arises with mind-contact as condition—whether pleasant or
  painful or neither-painful-nor-pleasant—that too is empty of self and
  of what belongs to self.
“It is, Ānanda, because it is empty of self and of what belongs to
  self that it is said, ‘Empty is the world.’”

So, from all the above sutta references, we can see that the self is just a mental idea, and apart from it, everything else of The All is empty of a self and empty of what belongs to a self. It is no point discussing if there is a self beyond The All.
The luminous mind is not anything permanent or unconditioned. That's discussed in this answer. It's simply an impermanently arising and ceasing mental state that is undefiled, that becomes defiled by incoming defilements in a non-arahant.
In this answer and this answer, we can see that Nibbana is not a self or a thought or consciousness or feeling or state of mind, and it is within The All as a phenomena that is a sense object for the mind. It's the only phenomena which is not conditioned, not compounded, not suffering, not impermanent, not arising, not ceasing and not changing.
Here, AN 9.34 gives us the hint about Nibbana:

Ven: Sariputta: “Reverends, extinguishment (Nibbana) is bliss!
Ven. Udayi: “But Reverend Sāriputta, what’s blissful about it, since
  nothing is felt?”
Ven. Sariputta: “The fact that nothing is felt is precisely what’s
  blissful about it.


user8157: SN 44.10 is not about anatta (not-self). 
In SN 44.10, based on the Buddha's final summation to Ananda, the befuddled Vacchagotta essentially asked: "Do I exist?" ("atthattā"); "Do I not exist?" (natthattā). Both questions of Vacchagotta included an implicit belief in "self". That is why they were faulty questions and the Buddha remained silent. As the Buddha concluded: 

If I had answered... Vacchagotta... would have got even more confused, thinking: ‘It seems that the self that I once had no longer exists.’

Vacchagotta never ever asked about "not-self" ("anatta"). That Ven. Thanissaro wrote an entire thesis based on the confused questions of Vacchagotta was probably one of the most embarrassing events ever in modern Theravada Buddhism.  
While my answer is sufficient to debunk the befuddlement of Ven. Thanissaro, Ven. Sujato replies to Ven. Thanissaro's befuddlement, here: On not-self, existence, and ontological strategies.

Also, 'sūnyatā' does not mean 'vacuity' or 'nothingness'.

Also, "anatta" is "ontological", i.e., an inherent natural reality unrelated to any human perception of it; as clearly said in AN 3.136. 

user43: There are several questions brought up here. One I see you asking: is the entire teaching of Buddha- with everything it has to offer -- is a true explanation of reality or is it merely a useful fiction, an expedient mean for achieving a goal (liberation from suffering)?
To me the answer is clear.
Any explanation of reality is a conceptual model. Every conceptual model is an abstract summary - leaving out some details, and emphasizing important features and relationships. Now, what do we mean when we say "important f&r"? Nothing can be important in and off itself. Something is important only inasmuch as it helps attaining some kind of objective. Important is always important "for something". This "important for something" is what defines which features and relationships we keep in our conceptual model and which details we omit. So any explanation of reality serves a purpose. This purpose determines the limits, the method, and the shape of the explanation.
Buddha's teaching is also like this, it is an explanation of reality serving the purpose of liberation from suffering.
It does NOT mean Dharma is a useful fiction. As any conceptual model it is a purpose-chosen subset of the Truth. But it's not enough for something to be true, indeed there is an infinite number of ways to slice and dice the same truth. Dharma must not only be True but also has to be useful. Buddha said times and again: the right speech is not just factual, it must be useful. He also said, in one of the suttas ("the safe bet") - if we assume Theory X as our working basis, how will this choice determine our future? Not every valid theory is useful. Dharma is famously "good in the beginning, good in the middle, and good in the end". 
So Buddha's teaching is an explanation of reality serving the purpose of liberation from suffering.
The second topic I wanted to take up, is your comments about Mahayana. The way you characterize Mahayana's position shows your very (VERY) shallow understanding of Mahayana in general and Madhyamaka in particular.
In the Mahayana it's even more obvious, we could talk about tathāgatagarbha, buddhadhātu, dharmakāya, dharmadhatu...

Absolutely all these concepts seem to me to be reinsertions through the window of the self thrown out the door. They all affirm, in one form or another, an ultimate reality, which they call "awareness" or "mind", a state of bliss… which literally corresponds to the Hindu definition of the supreme self.

I suggest that you educate yourself to the Rangtong-Shentong debate before making any statements equating Mahayana's position(s) with Hinduism.
In Mahayana tradition, there's a very clear understanding that Buddha's message comes in multiple stages, called Gradual Training. Theravada recognizes this, too. The teaching is organized in levels from the most simplified to the most accurate. The teaching about rebirth is the most basic. The teaching about Anica, Dukkha, Anatta, Four Noble Truths, Dependent Origination - are intermediate. But what is the ultimate teaching?
To me, Buddha's ultimate position is made clear in the Aggi-Vacchagotta Sutta:

"Does Master Gotama have any position at all?"
"A 'position,' Vaccha, is something that a Tathagata has done away with.
...  
Because of this, I say, a Tathagata — with the ending, fading away, cessation, renunciation, & relinquishment of all construings, all excogitations, all I-making & mine-making & obsessions with conceit — is, through lack of clinging/sustenance, released."

Thanissaro Bhikkhu has a pretty nice post about the levels of teaching, which by the way, also shows how even the teaching of Anatta is transcended on the ultimate level:  https://www.dhammatalks.org/books/OnThePath/Section0008.html

12857: <p><em>(English is not my mother tongue, sorry in advance if I make mistakes)</em></p>

<p>I recently read Thanissaro Bhikkhu's writings <a href="https://www.dhammatalks.org/Archive/Writings/Ebooks/SelvesAndNot-self_181215.pdf" rel="noreferrer">[1]</a> <a href="https://www.dhammatalks.org/Archive/Writings/CrossIndexed/Uncollected/MiscEssays/NotSelfRevisited171126.pdf" rel="noreferrer">[2]</a> on anatta and although I found his arguments persuasive I am still conflicted.</p>

<p>I invite you to read them at least in part before reacting as they are rich in arguments and answers to the first objections that might come to mind.</p>

<p>Nevertheless, I quote TB's summary of his thesis and the objections he encountered:</p>

<blockquote>
  <p>These reflections were sparked recently by reading a critique of an article I wrote in 1993, called “The Not-self Strategy.” The thesis of that article (available in the essay collection Noble &amp; True)—which I revised in 2013 both to tighten and to expand the presentation—was that the Buddha intended his teaching on not-self (anattā), not as an answer to the metaphysical/ontological question, “Is there a self?” but as a strategy for cutting through clinging to the five aggregates and so to put an end to suffering. The main argument I presented in support of this thesis in both versions of the article was that the one time the Buddha was asked point-blank, “Is there a self?”… “Is there no self?” he remained silent (SN 44.10). Similarly, in MN 2, he stated that such questions as “Do I exist?” “Do I not exist?” and “What am I?” are not worthy of attention because they lead to conclusions that fetter a person in a “thicket of views” and a “fetter of views,” including the views that “I have a self” and “I have no self.” In other words, any attempt to answer these questions constituted a side road away from the path of right practice.</p>
  
  <p>The critique—“Anattā as Strategy and Ontology,” written by Ven. Bhikkhu Bodhi—was brought to my attention just over a month ago, even though it has apparently been around for some time. It takes issue both with the thesis and with the argument of my article, but in doing so it displays the scholarly bias mentioned above: that the practice of the Buddha’s teachings is primarily a process of leading the meditator to give full assent to the accuracy of those teachings as a description of reality, and that this assent is what frees the mind from suffering. Because this bias is not only the bias of the critique, but of so much thought in the Buddhist world, I thought it might be useful to explore how both the thesis of the critique and the arguments used in support of that thesis display this bias, so that it can be recognized for what it is not only in this case but also in other Buddhist writings.</p>
</blockquote>

<p>I came across <a href="https://discourse.suttacentral.net/t/bodhi-vs-hanissaro-debate/7348" rel="noreferrer">this page</a> where Buddhists are debating the view of TB in opposition to Bhikkhu Bodhi's response. In particular, I found <a href="https://discourse.suttacentral.net/t/bodhi-vs-hanissaro-debate/7348/89" rel="noreferrer">this answer</a> interesting.</p>

<p>I'd like to hear your views on the arguments on both sides. Anatta: only a strategy for realization or a real "ontological" position?</p>

<p>Among the <a href="https://en.wikipedia.org/wiki/Three_marks_of_existence" rel="noreferrer">trilakkhanas</a>, anatta is really the one I have the most trouble with. I can't understand it. And the more I learn about it, the more I realize that Buddhists don't seem to understand it either, given all the disagreements on the subject. Even within Theravada, many ajahn of the Thai Forest Tradition seem to reintroduce a form of self by talking about the <a href="https://en.wikipedia.org/wiki/Thai_Forest_Tradition#Original_mind" rel="noreferrer">"mind that does not disappear, immutable and indestructible reality"</a> (which clearly resembles the Hindu <a href="https://en.wikipedia.org/wiki/%C4%80tman_(Hinduism)" rel="noreferrer">atman</a> / <a href="https://en.wikipedia.org/wiki/Purusha" rel="noreferrer">purusha</a>). Ajahn Maha Bua, considered by his peers to be an arhat, stated that he <a href="https://en.wikipedia.org/wiki/Ajahn_Maha_Bua#Some_basic_teachings_on_the_&#39;Citta&#39;" rel="noreferrer">"observes the essential enduring truth of the sentient being as constituted of the indestructible reality of the citta (heart/mind), which is characterized by the attribute of Awareness or Knowingness. This citta, which is intrinsically bright, clear, and Aware, gets superficially tangled up in samsara but ultimately cannot be destroyed by any samsaric phenomenon."</a>.</p>

<p>In the Mahayana it's even more obvious, we could talk about <a href="https://en.wikipedia.org/wiki/Buddha-nature" rel="noreferrer">tathāgatagarbha, buddhadhātu,</a> <a href="https://en.wikipedia.org/wiki/Dharmak%C4%81ya" rel="noreferrer">dharmakāya,</a> <a href="https://en.wikipedia.org/wiki/Dharmadhatu#Definition" rel="noreferrer">dharmadhatu</a>...</p>

<p>Absolutely all these concepts seem to me to be reinsertions through the window of the self thrown out the door. They all affirm, in one form or another, an ultimate reality, which they call "awareness" or "mind", a state of bliss… wich literally corresponds to the <a href="https://en.wikipedia.org/wiki/Satcitananda" rel="noreferrer">Hindu definition of the supreme self.</a></p>

<p>Yet the Buddha seems to speak explicitly of this state and describe it as just a step towards the summit:</p>

<blockquote>
  <p>Furthermore, a mendicant—ignoring the perception of earth and the perception of the dimension of infinite space—focuses on the oneness dependent on the perception of the dimension of infinite consciousness. (…)</p>
  
  <p> <a href="https://suttacentral.net/mn121/en/sujato" rel="noreferrer">https://suttacentral.net/mn121/en/sujato</a></p>
</blockquote>

<p>Even vacuity (sūnyatā) does not seem to be the destination, <a href="https://en.wikipedia.org/wiki/Dhy%C4%81na_in_Buddhism#The_arupas" rel="noreferrer">the infinite nothingness being only a penultimate stage of the jhanas</a>.</p>

<p>What should we think about all this? At the end of the day, it seems to me that the subject can be summed up in one question:</p>

<p>It is often said that the Buddha would have affirmed that all phenomena are without self: <code>sabbe dhamma anatta</code></p>

<p>Then the question arises as to whether Nibbana is a phenomenon (dhamma) or not. If this is not the case, <a href="https://essenceofbuddhism.wordpress.com/2016/07/23/sabbe-dhamma-anatta-did-the-buddha-really-teach-that-there-is-no-self/" rel="noreferrer">as some people maintain</a>, it is logical to consider that the supreme reality, being neither impermanent nor dukkha, does not possess the third seal of the no(t)-self either, and to start talking about this supreme mind, awareness, etc., which is not a dhamma, but a permanent and blissful source of all impermanent and unsatisfactory phenomena - by the way, <em>how better to define the phenomenon than as what appears in consciousness</em>? -; in this case, the border with the Hindu atman-brahman becomes extremely thin, not to say non-existent. If, on the contrary, Nibbana is also a phenomenon (dhamma), having no self, the difference with Hindu thought remains but then, what about the other two seals of all phenomena: anicca and dukkha? How to apply them to Nibbana?</p>

<p>Maybe, like dukkha and anicca, anatta must be abandoned once the destination is reached.</p>
 13375: <p><strong>I'd like to hear your views on the arguments on both sides. Anatta: only a strategy for realization or a real "ontological" position?</strong></p>

<p>It is both. </p>

<p>It is a fact that the direct realization of emptiness is the true antidote to all that ails us in samsara. As such, we must not minimize the importance of annata - it's true understanding and direct realization of it - as the ultimate way to fulfill the soteriological aims of the Dharma. There is no substitute. Only a full and complete and direct realization of anatta will accomplish our aims.</p>

<p>On the other hand, the emptiness of all phenomena - and its flip side dependent arising - is the ultimate truth. If is the supreme fact of existence. I would not describe it as '<em>a real ontological position</em>' but if I can infer what you are after with those words... then I'd say, yes, <em>more or less</em> that is what you arrive at or at least it is a necessary step on the path to a direct realization.</p>

<p>Often times, people who don't understand anatta or are confused by it - even at a correct, but limited intellectual/conceptual level - fall back to the thicket of views sutta. But this is sour grapes. And rightly so. This is dangerous stuff. But there <em>is</em> a correct intellectual and conceptual understanding of anatta and it <em>is</em> extremely hard to arrive at and it <em>is</em> by no means sufficient to stop at this level. It <em>is</em> absolutely necessary to arrive at this level - a correct conceptual/intellectual understanding - before proceeding to a direct realization. </p>

<p>The truth is that most lowly beings are not even close to a correct conceptual understanding of anatta and that trying too hard to reach this <strong>level can be dangerous to them.</strong> That is why the Buddha gave the thicket of views admonition and was silent. <strong>He was dealing with an audience that simply was not ready to go further.</strong> They did not have the requisite merit to proceed and had they done so at that time they would have harmed themselves. So the Buddha was compassionately telling them what they needed at that time to prevent them from harming themselves.</p>

<p>What people don't understand is that a correct understanding of annata - while absolutely necessary to completing the soteriological goals of the lowly beings - is also extremely dangerous thing to wrestle with. <strong>It is a snake that incorrectly grasped will bite and send beings into the lowest of hell worlds, but correctly grasped can be used to extract venom that can be turned into the ultimate medicine.</strong> If incorrectly grasped, people will fall to extreme views of annihilationism or eternalism which will wreck their practice and decimate the stores of merit they have built up.</p>

<p>Understanding annata is <em>hard</em> and it is <em>extremely dangerous</em> and it is <em>absolutely necessary and indispensable</em> to achieving the aims of the Buddha for all of us beings. That is why it is so important to have good self assessment for both <em>teachers</em> and <em>students</em> and to understand the risks and rewards. This is dangerous and delicate business. Guard rails are present and are in the suttas and people should heed those warnings and use those guard rails lest they fall into ruin.</p>
 471: <p><strong>I'd like to hear your views on the arguments on both sides. Anatta: only a strategy for realization or a real "ontological" position?</strong></p>

<p>It is both.</p>

<p>From <a href="https://www.accesstoinsight.org/tipitaka/kn/snp/snp.4.14.than.html" rel="nofollow noreferrer">Sutta Nipata 4.14</a>:</p>

<blockquote>
  <p>Seeing in what way is a monk unbound,<br>
  clinging to nothing in the world?"<br>
  "He should put an entire stop<br>
  to the root of objectification-classifications:<br>
  'I am the thinker.'</p>
</blockquote>

<p>This answer talks about a strategy for freedom from suffering, but it also offers an ontological position concerning the self. "I am the thinker" is the hint.</p>

<p>The self is simply a mental idea, a thought, a view. It's an impermanent thought that arises and ceases from time to time.</p>

<p>With the self mental idea as reference, one objectifies and classifies (or reifies) everything else as non-self things. That's <em>papanca</em>. <a href="https://buddhism.stackexchange.com/a/31935/471">This answer</a> connects self and reification to craving and suffering. <a href="https://buddhism.stackexchange.com/q/28981/471">This question</a> connects Theravada emptiness to Mahayana emptiness.</p>

<p>It may be argued that apart from the mental idea of the self, there is some other self, that is the True Self.</p>

<p>For this, the answer comes in 2 suttas. The first is the <a href="https://suttacentral.net/sn35.23/en/bodhi" rel="nofollow noreferrer">SN 35.23</a>:</p>

<blockquote>
  <p>“And what, bhikkhus, is the all? The eye and forms, the ear and
  sounds, the nose and odours, the tongue and tastes, the body and
  tactile objects, the mind and mental phenomena. This is called the
  all.</p>
  
  <p>“If anyone, bhikkhus, should speak thus: ‘Having rejected this all, I
  shall make known another all’—that would be a mere empty boast on his
  part. If he were questioned he would not be able to reply and,
  further, he would meet with vexation. For what reason? Because,
  bhikkhus, that would not be within his domain.”</p>
</blockquote>

<p>If there is something that is the True Self, it must be within the range of The All.</p>

<p>And then from <a href="https://suttacentral.net/sn35.85/en/bodhi" rel="nofollow noreferrer">SN 35.83</a>:</p>

<blockquote>
  <p>“It is, Ānanda, because it is empty of self and of what belongs to
  self that it is said, ‘Empty is the world.’ And what is empty of self
  and of what belongs to self? The eye, Ānanda, is empty of self and of
  what belongs to self. Forms are empty of self and of what belongs to
  self. Eye-consciousness is empty of self and of what belongs to self.
  Eye-contact is empty of self and of what belongs to self…. Whatever
  feeling arises with mind-contact as condition—whether pleasant or
  painful or neither-painful-nor-pleasant—that too is empty of self and
  of what belongs to self.</p>
  
  <p>“It is, Ānanda, because it is empty of self and of what belongs to
  self that it is said, ‘Empty is the world.’”</p>
</blockquote>

<p>So, from all the above sutta references, we can see that the self is just a mental idea, and apart from it, everything else of The All is empty of a self and empty of what belongs to a self. It is no point discussing if there is a self beyond The All.</p>

<p>The luminous mind is not anything permanent or unconditioned. That's discussed in <a href="https://buddhism.stackexchange.com/a/25212/471">this answer</a>. It's simply an impermanently arising and ceasing mental state that is undefiled, that becomes defiled by incoming defilements in a non-arahant.</p>

<p>In <a href="https://buddhism.stackexchange.com/a/31061/471">this answer</a> and <a href="https://buddhism.stackexchange.com/a/31737/471">this answer</a>, we can see that Nibbana is not a self or a thought or consciousness or feeling or state of mind, and it is within The All as a phenomena that is a sense object for the mind. It's the only phenomena which is not conditioned, not compounded, not suffering, not impermanent, not arising, not ceasing and not changing.</p>

<p>Here, <a href="https://suttacentral.net/an9.34/en/sujato" rel="nofollow noreferrer">AN 9.34</a> gives us the hint about Nibbana:</p>

<blockquote>
  <p>Ven: Sariputta: “Reverends, extinguishment (Nibbana) is bliss!</p>
  
  <p>Ven. Udayi: “But Reverend Sāriputta, what’s blissful about it, since
  nothing is felt?”</p>
  
  <p>Ven. Sariputta: “The fact that nothing is felt is precisely what’s
  blissful about it.</p>
</blockquote>
 8157: <p>SN 44.10 is not about anatta (not-self). </p>

<p>In SN 44.10, based on the Buddha's final summation to Ananda, the befuddled Vacchagotta essentially asked: "<em>Do I exist?</em>" ("<em>atthattā</em>"); "<em>Do I not exist?</em>" (<em>natthattā</em>). Both questions of Vacchagotta included an implicit belief in "self". That is why they were faulty questions and the Buddha remained silent. As the Buddha concluded: </p>

<blockquote>
  <p><em>If I had answered... Vacchagotta... would have got even more confused, thinking: ‘It seems that <strong>the self that I once had</strong> no longer exists.’</em></p>
</blockquote>

<p>Vacchagotta never ever asked about "not-self" ("anatta"). That Ven. Thanissaro wrote an entire thesis based on the confused questions of Vacchagotta was probably one of the most embarrassing events ever in modern Theravada Buddhism.  </p>

<p>While my answer is sufficient to debunk the befuddlement of Ven. Thanissaro, Ven. Sujato replies to Ven. Thanissaro's befuddlement, here: <a href="https://discourse.suttacentral.net/t/on-not-self-existence-and-ontological-strategies/11836" rel="nofollow noreferrer">On not-self, existence, and ontological strategies</a>.</p>

<hr>

<p>Also, 'sūnyatā' does not mean 'vacuity' or 'nothingness'.</p>

<hr>

<p>Also, "anatta" is "ontological", i.e., an inherent natural reality unrelated to any human perception of it; as clearly said in <a href="https://suttacentral.net/an3.136/en/sujato" rel="nofollow noreferrer">AN 3.136</a>. </p>
 43: <p>There are several questions brought up here. One I see you asking: is the entire teaching of Buddha- with everything it has to offer -- is a true explanation of reality or is it merely a useful fiction, an expedient mean for achieving a goal (liberation from suffering)?</p>

<p>To me the answer is clear.</p>

<p>Any explanation of reality is a conceptual model. Every conceptual model is an abstract summary - leaving out some details, and emphasizing <em>important</em> features and relationships. Now, what do we mean when we say "important f&amp;r"? Nothing can be important in and off itself. Something is important only inasmuch as it helps attaining some kind of objective. Important is always important "for something". This "important for something" is what defines which features and relationships we keep in our conceptual model and which details we omit. So any explanation of reality serves a purpose. This purpose determines the limits, the method, and the shape of the explanation.</p>

<p>Buddha's teaching is also like this, it is an explanation of reality serving the purpose of liberation from suffering.</p>

<p>It does NOT mean Dharma is a useful fiction. As any conceptual model it is a purpose-chosen subset of the Truth. But it's not enough for something to be true, indeed there is an infinite number of ways to slice and dice the same truth. Dharma must not only be True but also has to be useful. Buddha said times and again: the right speech is not just factual, it must be useful. He also said, in one of the suttas ("the safe bet") - if we assume Theory X as our working basis, how will this choice determine our future? Not every valid theory is useful. Dharma is famously "good in the beginning, good in the middle, and good in the end". </p>

<p>So Buddha's teaching is <strong>an</strong> explanation of reality serving the purpose of liberation from suffering.</p>

<p>The second topic I wanted to take up, is your comments about Mahayana. The way you characterize Mahayana's position shows your very (VERY) shallow understanding of Mahayana in general and Madhyamaka in particular.</p>

<pre><code>In the Mahayana it's even more obvious, we could talk about tathāgatagarbha, buddhadhātu, dharmakāya, dharmadhatu...

Absolutely all these concepts seem to me to be reinsertions through the window of the self thrown out the door. They all affirm, in one form or another, an ultimate reality, which they call "awareness" or "mind", a state of bliss… which literally corresponds to the Hindu definition of the supreme self.
</code></pre>

<p>I suggest that you educate yourself to <a href="https://en.wikipedia.org/wiki/Rangtong-Shentong" rel="nofollow noreferrer">the Rangtong-Shentong debate</a> before making any statements equating Mahayana's position(s) with Hinduism.</p>

<p>In Mahayana tradition, there's a very clear understanding that Buddha's message comes in multiple stages, called Gradual Training. Theravada recognizes this, too. The teaching is organized in levels from the most simplified to the most accurate. The teaching about rebirth is the most basic. The teaching about Anica, Dukkha, Anatta, Four Noble Truths, Dependent Origination - are intermediate. But what is the ultimate teaching?</p>

<p>To me, Buddha's <em>ultimate</em> position is made clear in the Aggi-Vacchagotta Sutta:</p>

<blockquote>
  <p>"Does Master Gotama have any position at all?"</p>
  
  <p>"A 'position,' Vaccha, is something that a Tathagata has done away with.</p>
  
  <p>...  </p>
  
  <p>Because of this, I say, a Tathagata — with the ending, fading away, cessation, renunciation, &amp; relinquishment <strong>of all construings, all excogitations</strong>, all I-making &amp; mine-making &amp; obsessions with conceit — is, through lack of clinging/sustenance, released."</p>
</blockquote>

<p>Thanissaro Bhikkhu has a pretty nice post about the levels of teaching, which by the way, also shows how even the teaching of Anatta is transcended on the ultimate level:  <a href="https://www.dhammatalks.org/books/OnThePath/Section0008.html" rel="nofollow noreferrer">https://www.dhammatalks.org/books/OnThePath/Section0008.html</a></p>
