Is Nibbana devoid of a permanent and eternal substance?

Is Nibbana devoid of a permanent and eternal substance? Nibbana is the name given for devoid of craving.

Also, is Nibbana a mere projection of human consciousness? It is a result of not having a craving.

Also, are all things "mere names"? No. There are Dependently originated phenomena.

Is Nibbana devoid of a permanent and eternal substance?

Also, is Nibbana a mere projection of human consciousness?

Also, are all things "mere names"?

Well, to be able to answer all 3 questions with guaranteed certainty, the obvious assumption and prerequisite is that the one who provides the answer's already truly had first-hand direct experience of Nibbana AND penetrated "all things"! While waiting for that precious enlightened being to show up here on buddhism.stackexchange.com, it might be a good idea to go with those definitions as taught in the suttas, and I'm sure you already knew a thing or two more than the average forum participants here on BSE when it comes to suttas knowledge.

Is Nibbana devoid of a permanent and eternal substance?

So the phrasing of this question makes it slightly difficult to answer, but I will do my best. I would answer in this way.

Nibbana is devoid of anything but itself. Nibbana is eternally present, but it is often described as “empty” or “devoid” because once it is experienced alone for the first time, the practitioner realizes that every day of their life they have experiencing Nibbana, but never noticed it due to it being “full” of other experiences. Hopefully my answer to your next question will clear up what I mean by this.

Also, is Nibbana a mere projection of human consciousness?

This is how I like to describe the structure of Nibbana, and how it fits in to our experience. This explanation is incomplete, but I think it accurately conveys its structure.

You can think of Nibbana as the totality of the universe. It is the only thing that actually exists. First Nibbana exists. Then, within Nibbana experiences appear. We call these experiences seeing, hearing, tasting, touching, smelling, and thinking. From these experiences, form is conceptualized, and the “physical” universe we believe to exist is born.

Nibbana is like a television. When a television is turned off, you could describe it as “empty”. Devoid of any content. When it is turned on, it does not create anything. The beings that exist within a TV do not physically exist. The sights it produces could not possibly exist outside of the TV, for the images themselves are the TV. The only thing that ever exists is the Television, and the forms that appear within it are still the TV, simply pixels modulating that we interpret as something more meaningful.

Have you ever been so focused on the content of a movie or show, the presence of the TV melts into the background? Have you ever had the experience of suddenly being pulled out of the show and realizing “oh yea, I’m just looking at a screen”? This experience is much like the feeling that occurs when you see Nibbana for the first time.

Nibbana is like a tv, modulating, taking the form of an image that we interpret as mental phenomena. Then we conceptualize the image/mental phenomena as form, and falsely believe the form has some independent (physical) existence outside of its mental appearance.

I would not say Nibbana is a projection of human consciousness. I would say human consciousness is a projection within Nibbana.

Also, are all things "mere names"?

I would say “all things are nothing more than concepts”. Trees, your mother, sadness, and mathematics all are the same thing. Nibbana. But with the appearance of thought usually comes also conceptualization. We single out a sight and sound we heard before and label that group of sense experiences as “Mother”. Everything you have a name for is conceptualized. What makes Nibbana so difficult to describe, is that Nibbana is what exists when no conceptualization is occurring. It’s logically impossible to describe such a thing, so we fall on words like “empty” as a poor attempt to describe what it’s like when no one is describing.

Although these questions are virtually impossible to answer outside of your own personal experience, I hope my very poor explanations have at least pointed you towards the answers you seek.

Is Nibbana devoid of a permanent and eternal substance?

Yes. As I read from scriptures Nibbana must be empty of permanent and eternal substance. In Root Of All Things sutta even Nibbana is understood as no Self which means it must be empty of permanent and eternal substance.

Also, is Nibbana a mere projection of human consciousness?

Nibbana is cessation or 'nirodh' of ignorance or craving. It is not a projection of human consciousness.

Also, are all things "mere names"?

No. Probably the question is invalid.That calls into question the understanding of reality. What is Universe? What is soul ? Are the body and soul separate or the same? To answer this Buddha mysteriously invokes the Middle Path saying on what conditions Ageing and Death come to be? On the condition of Birth. On what conditions Birth come to be ? On the condition of existence. On what conditions Existence come to be ?....etc. Existence has all the things and consciousness. Therefore it will be foolish to say all things are mere names because reality doesnt come about to be that way.

All things are mere names, just biased delineations.

The idea and name of nibbana are mere projections of consciousness. Nibbana is only direct experience.

Direct experience of what is permanent? Direct experience without names is not impermanent - there is no thing for a name to latch on to.

I know based on your tags that your point is "those crazy Mahayanists love to speculate and philosophize, their minds consumed by papanca". And yet, the release from papanca through a kind of philosophical catharsis is exactly what the authors aimed at (as we know from numerous commentaries and sub-commentaries).

So you are asking questions which have been endlessly debated, nitpicked, and split-haired all over commentarial literature for centuries. Don't expect a simple answer.

One way to look at it: if things (dharmas) are called "empty" because they are conditional, constructed (samskara), and dependently originated - is Nirvana, too, dependently originated OR is Nirvana the Dependent Origination itself?

If it's the second, then is Dependent Origination itself dependently originated or is it unconditional, unborn, and undying?

Another way to look at it, is: if all experiences (vijnapti) are relative to the experiencer and the experiencer's model of perception/interpretation, isn't experience of Nirvana also such? Is Nirvana experienced (vijnana) by an experiencer according to his models and interpretations or is it cessation of all models and interpretations that we call Nirvana? If so, can it be called "an experience"? Can we call Nirvana "an experienced phenomena"? If no, then "all experienced phenomena are empty" may not apply to Nirvana. If all experience ceases in Nirvana, can we really say "Nirvana can be seen by the wise" other than as a metaphor for realizing the limit of models and interpretations?

Yet another way to look at it. If Nirvana is metaphor for cessation of craving, is this cessation conditional on being attained or is it unborn and undying? In other words, does peace exist "primordially" even when we are at war, or is it a "projection of mind" at that moment?

Can these questions be answered conclusively, or is any answer necessarily dependent on our definitions and interpretations? Where does this leave us? ;)

From this page, according to Nagarjuna's MMK, XXIV, 18 - 19:

18. Whatever is relativity, we proclaim that emptiness. It is dependent designation. It is also the central way.
19. Nothing whatsoever is found which is not relativistically originated. Therefore, nothing whatsoever is found which is not empty.

A fish spends all its time in water, but may not understand what water means, unless it leaves it momentarily.

Similarly, from my understanding of Nagarjuna, if you have no samsara, then no one would understand what Nirvana means. Nirvana is identified only to contrast it with samsara. Hence, Nirvana is empty of an intrinsic essence, because its definition is relativistic i.e. relative to samsara.

Also, from this page:

Nevertheless to assert that all things are empty of any intrinsic reality, for Nāgārjuna, is not to undermine the existential status of things as simply nothing. On the contrary, Nāgārjuna argues, to assert that the things are empty of any intrinsic reality is to explain the way things really are as causally conditioned phenomena (pratītyasamputpaṅhā).

This means Nagarjuna does not say that Nirvana does not exist or is nothing. Rather he says that it depends on something else. Nirvana does not substantially depend on samsara i.e. it is not conditioned or compounded by anything. However, it depends on samsara for its relativistic definition i.e. Nirvana depends on samsara semantically, rather than substantially.

Another analogy is this - if a tree falls in a forest, but there is no one there to listen to it, does it still make a sound? The sound of a tree falling is only defined relative to a listener. If there is no listener, then it does not make sense to identify sound as such. But it does not mean that it doesn't exist. Similarly, in the case of Nirvana, it is defined relative to samsara.

Nagarjuna is really discussing the mental concept of Nirvana, rather than Nirvana itself.