How can all dharmas have no intrinsic reality logically speaking?

There Can Only Be Two Types of Realities (Dharmas)

The word "realities" appears inappropriate because this word itself appears to imply some sort of esoteric connotation. The proper terms to use are "things", "phenomena" or "elements".

1.Conditioned... depends on something for its existence.

Yes.

2.Unconditioned... self-sufficient, i.e. does not depend on anything else for its existence.

In Buddhism, the Nibbana Element is the Unconditioned

A conditioned Dharma cannot be caused by a finite series of conditioned Dharma: If there is a linear series of conditioned Dharma, what would the first one depend on? Since it must depend on something, and there is nothing before it, the whole chain ceases to exist.

The Buddha did not always declare a preceding cause ("hetu") of all conditioned things. In AN 10.61, it is said a preceding cause of ignorance cannot be found. However, AN 10.61 does say ignorance has a "condition" ("paccaya") of "nutriment" ("ahara") that sustains the existence of ignorance. That "nutriment" itself is a product of ignorance but when that nutriment (namely, the five hindrances) is removed, ignorance will diminish and cease. Therefore, ignorance is conditioned, even though a preceding cause of ignorance is unknown.

A thing can be "conditioned" due to having: (i) a preceding cause (hetu); (ii) a condition (paccaya); or (iii) nutriment (ahara). These three words are not necessarily synonymous.

Thus a linear chain of conditioned realities cannot exist. Additionally, a circular finite chain of conditioned Dharmas could not exist either. This would simply result in each conditioned reality fulfilling their own conditions, which is against the definition of a conditioned Dharma.

In the Kalama Sutta, the Buddha said to not always rely on what today is called "logic". For spiritual matters, "logic" does not always work.

Continuously adding to the end of the chain would never allow for the conditions of existence to be satisfied, thus the entire infinite chain of conditioned Dharmas would never have its conditions fulfilled.

I struggled to comprehend the above clearly however i wish to mention that prior causes generally cease. For example, the last in-breath my life depended on has now ceased. That in-breath of oxygen has transformed into an out-breath of carbon dioxide that has now gone to a different place and transformed into something else. I suppose I am saying there appears no tangible "chain" of causes & conditions that remains tied together.

the complete set of infinite conditioned Dharma would be an unconditioned Dharma.

Yes. If we use the characteristic dhamma of "permanence" to define the 'unconditioned", then the Law of Nature is an "infinite" dhamma that gives the impression of being made up of conditioned things. In other words, the Law of Cause & Effect is permanent, even though it exhibits itself in relation to impermanent conditioned things.

In AN 3.136 & SN 12.20, the Buddha said the Law of Nature (Dhamma Nimaya) is fixed & unchanging; such as the impermanence of conditioned things is a permanent phenomena.

However, this is impossible because an unconditioned dharma cannot depend upon an aggregate of conditioned dharmas . if this were the case, it would be conditioned.

No. I already explained this. The permanence of impermanence does not make the impermanence impermanent; just as a barn full of chickens does not make the barn into a chicken. The law of impermanence is permanent; just as a barn is not a chicken.

Therefore, a set of infinite conditioned realities is itself a conditioned reality, and fails to exist on its own.

No. The conditioning or cause & effect nature of the stream of discrete conditioned things remains a fixed constant. In other words, each discrete conditioned thing or element each has an impermanent nature. So the "sabhava" or "inherent nature" of all impermanent conditioned remains the same & is permanent. The conditioned nature of an impermanent thing is a permanent quality it permanently retains.

Since any model made up entirely of conditioned Dharmas can never have their conditions fulfilled, every conditioned Dharma must be caused by a series of realities that ends (or begins its ontological Series) with an unconditioned Dharma.

I would say the series of dhammas is held together by an unconditioned dhamma, namely, the permanence of the impermanence; the permanence of the cause & effect.

Thus it Seems that a intrinsic Existance does exist? So how can Shunyata and sarva dharma anatta be True?

Shunyata and sarva dharma anatta are true because they have intrinsic existence (AN 3.136). Nibbana also has intrinsic existence (Udāna 8.3).

Unlike Nagarjuna, Theravadins do not dispute "sabhava" or "intrinsic existent".

So how can Shunyata and sarva dharma anatta be True?

Because it is quite the relief from suffering that such thoughts and questions have no foothold in emptiness.

MN121:12.6: And so they regard it as empty of what is not there, but as to what remains they understand that it is present.
MN121:12.7: That’s how emptiness is born in them—genuine, undistorted, and pure.
MN121:13.1: Whatever ascetics and brahmins enter and remain in the pure, ultimate, supreme emptiness—whether in the past, future, or present—all of them enter and remain in this same pure, ultimate, supreme emptiness.
MN121:13.4: So, Ānanda, you should train like this: ‘We will enter and remain in the pure, ultimate, supreme emptiness.’

Good householder. Higher Dhamma isn't taught to people still attached to sensuality and views, as it either cause total confusion or development of most dangerous householder-equanimity, a state where one has no fear in wrongdoing, even stealing from and harming the Noble Ones. In this 'emptiness' they shameless consume and harm, invite others, as requiring supplying, to do likewise.

How ever, if willing to seek refuge into the Gems, rather then in shameless thieves, this teaching could, if respectful received, help to get out of the 'paradox' toward clear vision: The Essence of the Dhamma.May it be assistance to walk toward the Deathless, take on the lifelihood of a Samana, leaving to live on not given, to be able to enter and remain not in blind consume but in real emptiness. When seeing some in pyjamas or jogging dress 'dwelling' there, that should be a clear reminder of the distinction, even outwardly.

"Ananda, what ever householder (bond to the strings of sensuality, house) thinks he dwells in emtiness, know him as heading downwardly as if been forced."

The Buddha was actually very harsh when seeing his disciples teaching high to minds totally caught in the world, and doing such, even the other wanderers, of the Mahayana sects, see it as a grave transgression, break of the Bodhisatta vows.

Perhaps you should have a good understanding of Culasunnata Sutta and Mahasunnata Sutta to know the Buddha's understanding of Sunnata. When you attain Nirodha Samapatthi you do not have the perception and feeling. So when you emerge from Nirodha Samapatthi you know that there is a state of Sunnata.

https://www.accesstoinsight.org/tipitaka/an/an04/an04.024.than.html

https://www.accesstoinsight.org/tipitaka/mn/mn.122.than.html

If you're speculating on the nature of the universe or the nature of existence, then the Buddha considered this a futile exercise of intellectual gymnastics that leads to madness in the Acintita Sutta:

"Conjecture about [the origin, etc., of] the world is an unconjecturable that is not to be conjectured about, that would bring madness & vexation to anyone who conjectured about it.

The Buddha only concerned himself with suffering, the cause of suffering, the cessation of suffering and the way to end suffering.

In the Parable of the Poisoned Arrow, he taught that a man struck with a poisoned arrow should find a way to remove the arrow and heal himself, rather than investigate who shot the arrow, and what is the arrow made of, and what does the arrow cost, and at what speed was it shot etc.

Of course, from the perspective of the individual, we may ask whether there is a self (i.e. an intrinsic unconditioned reality for a person) or not, and this is indeed related to the path to the end of suffering.

And the answer is clear from the Vina Sutta that the self is a mere mental idea (supported also by Snp 4.14), conjured by the five aggregates of form, feeling, perception, consciousness and mental formations, according to the process of dependent origination:

"Suppose there were a king or king's minister who had never heard the sound of a lute before. He might hear the sound of a lute and say, 'What, my good men, is that sound — so delightful, so tantalizing, so intoxicating, so ravishing, so enthralling?' They would say, 'That, sire, is called a lute, whose sound is so delightful, so tantalizing, so intoxicating, so ravishing, so enthralling.' Then he would say, 'Go & fetch me that lute.' They would fetch the lute and say, 'Here, sire, is the lute whose sound is so delightful, so tantalizing, so intoxicating, so ravishing, so enthralling.' He would say, 'Enough of your lute. Fetch me just the sound.' Then they would say, 'This lute, sire, is made of numerous components, a great many components. It's through the activity of numerous components that it sounds: that is, in dependence on the body, the skin, the neck, the frame, the strings, the bridge, and the appropriate human effort. Thus it is that this lute — made of numerous components, a great many components — sounds through the activity of numerous components.'

"Then the king would split the lute into ten pieces, a hundred pieces. Having split the lute into ten pieces, a hundred pieces, he would shave it to splinters. Having shaved it to splinters, he would burn it in a fire. Having burned it in a fire, he would reduce it to ashes. Having reduced it to ashes, he would winnow it before a high wind or let it be washed away by a swift-flowing stream. He would then say, 'A sorry thing, this lute — whatever a lute may be — by which people have been so thoroughly tricked & deceived.'

"In the same way, a monk investigates form, however far form may go. He investigates feeling... perception... fabrications... consciousness, however far consciousness may go. As he is investigating form... feeling... perception... fabrications... consciousness, however far consciousness may go, any thoughts of 'me' or 'mine' or 'I am' do not occur to him."

Then you may say consciousness is intrinsic and unconditioned, but even this is rubbished by the Buddha in MN 38, as he proves beyond any doubt that consciousness is conditioned upon the sensory media:

“Bhikkhus, consciousness is reckoned by the particular condition dependent upon which it arises. When consciousness arises dependent on the eye and forms, it is reckoned as eye-consciousness; when consciousness arises dependent on the ear and sounds, it is reckoned as ear-consciousness; when consciousness arises dependent on the nose and odours, it is reckoned as nose-consciousness; when consciousness arises dependent on the tongue and flavours, it is reckoned as tongue-consciousness; when consciousness arises dependent on the body and tangibles, it is reckoned as body-consciousness; when consciousness arises dependent on the mind and mind-objects, it is reckoned as mind-consciousness. Just as fire is reckoned by the particular condition dependent on which it burns—when fire burns dependent on logs, it is reckoned as a log fire; when fire burns dependent on f*ggots, it is reckoned as a f*ggot fire; when fire burns dependent on grass, it is reckoned as a grass fire; when fire burns dependent on cowdung, it is reckoned as a cowdung fire; when fire burns dependent on chaff, it is reckoned as a chaff fire; when fire burns dependent on rubbish, it is reckoned as a rubbish fire—so too, consciousness is reckoned by the particular condition dependent on which it arises. When consciousness arises dependent on the eye and forms, it is reckoned as eye-consciousness…when consciousness arises dependent on the mind and mind-objects, it is reckoned as mind-consciousness.

The Buddha also taught in the Sabba Sutta, not to imagine realities beyond the six sensory media:

The Blessed One said, "What is the All? Simply the eye & forms, ear & sounds, nose & aromas, tongue & flavors, body & tactile sensations, intellect & ideas. This, monks, is called the All. Anyone who would say, 'Repudiating this All, I will describe another,' if questioned on what exactly might be the grounds for his statement, would be unable to explain, and furthermore, would be put to grief. Why? Because it lies beyond range."

The concept of an intrinsic unconditioned reality is a mere philosophical conjecture and intellectual gymnastics, based on the false view of the self, no different from creationists trying to defend creationism against evolution using rhetorics.

The Buddha's teachings are grounded on his empirical realization of the four noble truths and the three marks of existence, and even today, these can be empirically verified through the Noble Eightfold Path.

Here's the traditional answer (straight from a Mahayana textbook so to speak, not making it up):

You imagine a chain of conditioned dharmas, one giving rise to another, but no such chain exists! - instead, the dharmas continuously morph and stir (like clouds) and this new configuration is what we call the subsequent dharmas.

When we say a dharma is conditioned by several preceding dharmas we just mean it's been created from them - not by them.

For convenience we say that preceding dharmas have to "cease" in order for the subsequent dharmas to "arise" but in fact this process is continuous. In fact "a dharma" is not something concrete and distinct with clear boundaries, whether spatial or temporal. We the observers make up those boundaries as we observe, just like with the clouds. This continuous process is what we're actually referring to when we say things are Anicca (impermanent) and Anatta (have no intrinsic identities).

So when you imagine your permanent and unconditioned creator called Ishvara, how do you think he creates the subsequent dharmas? This idea of Ishvara creating dharmas while himself staying unchanged can only make sense if future dharmas were something new and distinct from past dharmas but that is not how things work!

Instead, the Ishvara would need to himself morph into the next dharmas. So maybe you're saying that the entire realm of the ever-morphing dharmas (the dharma-dhatu) is what you call Ishvara? In other words, your Unconditioned Reality is the Law of Morphing, the Law of Dependent Origination?

If that's the case then you are in agreement with Buddha, you're just calling it a different name. Buddha called it The Dharma while you're calling it Ishvara. The choice of name is up to you, as long as you get the point.