How do the "rationalists" (those who try to just depend on what they have already understood) argue how and why they come into being with all their diversity, desires, character... and where is might disapear intom From nothing to nothing? God? Mystic? A mysterious plan?

Is there any valid argument beside of the fact of being reborn and that birth has a cause?

And what is the cause of birth?

Then, in the first watch of the night, he gave close attention to dependent co-arising in forward and reverse order:

From ignorance as a requisite condition come fabrications. From fabrications as a requisite condition comes consciousness. From consciousness as a requisite condition comes name-&-form. From name-&-form as a requisite condition come the six sense media. From the six sense media as a requisite condition comes contact. From contact as a requisite condition comes feeling. From feeling as a requisite condition comes craving. From craving as a requisite condition comes clinging/sustenance. From clinging/sustenance as a requisite condition comes becoming. From becoming as a requisite condition comes birth. From birth as a requisite condition, then aging-&-death, sorrow, lamentation, pain, distress, and despair come into play. Such is the origination of this entire mass of suffering & stress.

From the remainderless fading and cessation of ignorance comes the cessation of fabrications. From the cessation of fabrications comes the cessation of consciousness. From the cessation of consciousness comes the cessation of name-&-form. From the cessation of name-&-form comes the cessation of the six sense media. From the cessation of the six sense media comes the cessation of contact. From the cessation of contact comes the cessation of feeling. From the cessation of feeling comes the cessation of craving. From the cessation of craving comes the cessation of clinging/sustenance. From the cessation of clinging/sustenance comes the cessation of becoming. From the cessation of becoming comes the cessation of birth. From the cessation of birth, then aging-&-death, sorrow, lamentation, pain, distress, and despair all cease. Such is the cessation of this entire mass of suffering & stress.

It's all around and within oneself possible to prove rebirth, day by day, moment by moment, and the truth of cessation of becoming can be proved as well. Just cut off not-knowing, ignorance, and the wheel is stopped: release. Real-ease.

[Note: This is a gift of Dhamma and not meant for commercial purpose or other low wordily gains by means of trade and exchange.]

The concept of karma, at core, is an expression of the cyclical nature of our universe. Day becomes night becomes day; storms alternate with calm, and sunny days with cloudy; seasons swing round and round; creatures are born and give birth to others like them; emotions rise and fade away, only to rise again later. This is part of why the breath is an important focus in many meditations. The breath naturally and inevitably cycles. We can't stop it, but it's not fixed; it shifts and changes as things shift and change around and within us, but it always goes and it always returns. In mathematics this is known as a chaotic orbit, where feedback interdependencies between forces produce unpredictable results with a recognizable pattern of repetition. It is very much a part of our world.

I imagine we can all see how the notion of rebirth would arise from this: if so many other things in the world come and go and come again, why not life itself? But fixating on the idea of rebirth tends to undercut the broader understanding of karma as cyclicality.

The notion of personal rebirth, as I see it, is a comforting simplification, bordering at times on superstition. The egoic self chafes at the idea that there is an end to its existence, so the egoic self imagines that it will go away and return in a different body when this body is done. But of course, Buddhist practice aims at putting this egoic self to rest, and if we let it rest then the idea of rebirth becomes more a matter of mimesis than reincarnation. The attitude we take towards the world is reflected in the world, such that it can be reborn in the world at a different place and time. If we move though the world with rage, we foster a world in which our kind of rage can build itself in others; if we move through the world craving sensual passions, we foster a world in which that desire for sensual passions is engendered in others. If we move through the world without clinging and craving, we foster a world in which we do not influence others to cling or crave, and those attitudes are not reborn.

I'm not saying that there is no personal rebirth. Maybe there is, in some way I don't understand. But if there is such a thing, it is unimportant in its own right, merely an aspect of the greater cyclical nature of the world.

It sounds to me like your understanding of rebirth directly contradicts your understanding of Anatta. Have you considered your current understanding of rebirth may be inaccurate?

Dharma is the truth, but must look into it logically, and understand fully, why waste time trying to learn advance Dharma when you cannot comprehend the basics properly? Best you learn about the basics.? You say you can accept 'Anatta' how can you accept 'Anatta' and why should you accept 'Anatta' ? Then you say that you can rationally accept that suffering arises from attachment, how is that possible for you to accept that when you have not understood how 'Anicca' contributes suffering to arise? Why do you say that meditation helps when you do not fully understand what it is for? Then you talk about a migration of consciousness, but do you understand anything at all what the consciousness is and why it arises? And you also mentioned transmigration - there is nothing migrate at all, if you understood the meaning of 'Anicca' and 'Anatta' you will soon realise your questions are not valid. This is the very reason Buddha put 'IGNORANCE' on top of the chart of Dependant Origination.

May I suggest you to learn first the meanings of the first five precepts properly and see if you can live according to those, when you start to live that way I guarantee you, everything will fall into place and then you will understand what Dharma is trying to say, Dharma is given to us by Buddha because he discovered that there is a never ending process of life existence and all life existences are un-satisfactory and brings suffering, therefore to stop the process of suffering in the cycle of existence (to liberate from suffering) he found a method and that is why he is known as Buddha. He gave his discovery to the world free of charge.

Everything in the cosmos exist moment to moment and keep changing, everything has three phases, nothing remains the same way, they appear, exist, disappear , same way Birth, decay, Death, and this process continues., new environment, new appearance new existence. (eg. A man lives happily, the next minute his whole life does a 180 deg change say he was charged with murder that he did not commit and end up in prison, his life situation has now completely changed, different environment, unknown people, fear, etc… although he is not clinically dead he is not the same person anymore because of his thinking pattern has changed. Re-Birth process is similar, because it is through your habits that give rise to cause (karma) and karma gives rise to a new existence, the new existence gives rise to more habits through new experiences, and this cycle goes on and on, basically it is the information super highway what we call samsara is the base for all existences.

By the way Buddha never had a religion and he rejected all 'Ism's and Dharma was and still is and will always be a living system, extremely simple system but you need tremendous amount of effort to practice.

‘Kalama Sutta’ “Now, Kalamas, don’t go by reports, by legends, by traditions, by scripture, by logical conjecture, by inference, by analogies, by agreement through pondering views, by probability, or by the thought, ‘This contemplative is our teacher.’ When you know for yourselves that, ‘These qualities are skillful; these qualities are blameless; these qualities are praised by the wise; these qualities, when adopted & carried out, lead to welfare & to happiness’ — then you should enter & remain in them.

The quote comes from Kalama Sutra (AN 3.65) and is often taken out of context, hence misunderstood.

People of Kalama found themselves bombarded by tens of spiritual teachers, each claiming authority and expertise in spiritual matters. These teachers' doctrines were rather different from each other, but each was presented as The truth. Each teacher seemed quite certain of himself and was able to articulate the teaching logically.

When Buddha on one of his tours around the country arrived at Kalama and presented his teaching, the citizens honestly told him, that what he posits as The truth, to them looks like yet another teaching. "Is there any way" they asked, "that we can figure out which of these teachings is real?"

And that's when Buddha gave his famous answer, the point of which:

It is by its results that a teaching should be evaluated.

• A teaching can be elaborate and logical, with precise definitions. According to some people's preconceptions, these are the marks of a true teaching.

• A teaching could be profound, deep and mysterious. Some people assume, if chasm is deep and they can't see the bottom, there must be something in there.

• A teaching could match student's view of the world, e.g. the scientific worldview, or a spiritual worldview, or both. Many people interpret Kalama Sutra this way, that they should not believe a teaching unless it matches "common sense". They don't seem to realize that what they assume as common sense is in fact the very tangle of preconceptions that holds them in Samsara.

• A teaching could go against student's preconceptions and introduce a completely new theory of everything. Some students are very excited about such esoteric teachings and their eyes glaze over teachers that, in their opinion, profanate Dharma by assuming it speaks about our everyday lives.

• A teacher can look confident and speak well, or be soft-spoken and funny, like Dalai Lama. Many people find it hard to relate to a teacher who mismatches their archetype of Sage or Wise Old Man.

According to Buddha, all these are secondary factors, that can't be used as identifying markers of Sat-Dharma (True/Eternal Law/Tradition). Instead, it is by the effects it brings out, both in student's psyche as well as in the world, that a teaching should be measured.

Sath-Dharma is famously good in the beginning, good in the middle and good in the end.

Good in the beginning means, even the outermost layer of Dharma, the one seen by others ( non-Buddhists), has good influence on people. Even the laypeople who don't really practice, but are merely guided by basic Dharma principles, benefit from it. They find that Dharma not only happens to match their highest secular moral and wisdom, but that while secular moral is often too flexible, the compass of Dharma never wavers. When followed at large, True Dharma must lead to reduced suffering and increased harmony in daily lives of common people.

Good in the middle means, when someone practices a slightly superficial version of Dharma, without fully understanding it yet, it greatly reduces amount of suffering one generates inside and around. Student learns to watch his mind and recognize its state, learns to stay mindful of the body and notice arising emotions, learns to not let harmful thoughts and emotions control him, learns to let go of attachments and preconceptions. This leads to increased quality of life, as the student can now stay cool through various life challenges.

Good in the end means, one eventually arrives at Liberating Realization, whereby one is no longer dominated by arbitrary formations, but can instead juggle formations freely.

While some kind of "Good in the end" is obviously the goal of all alternative teachings, it is "Good in the middle" and "Good in the beginning" that is a characteristic mark of True Dharma.

So when Gautama said, "do not believe anything I say until you can prove it by yourself" (or however you want to put it), this is what he meant. He did not mean we should reject a teaching unless it matches our preconceptions. He meant we should evaluate a teaching by its effect on our lives. The proof is in the pudding.

Rebirth is regarded by the Supreme Buddha as essential and foundational to the pursuit of His teachings. This is very evident and is clearly illustrated in the Dependent Origination (Paticca samuppāda) that the being is born in the Becoming (bhava) caused by the grasping or attachment (upādāna) as stated "Upādāna paccaya bhavō, bhava paccaya jati...," But many people have mistaken the Becoming given here to soul or ego (ātma). This clearly shows that 'Rebirth' is integral to the Dependent Origination taught by the Supreme Buddha and is one of the twelve reasons that all of us are unable to comprehend. What are these twelve reasons?

Dependent on ignorance or lack of knowledge arises volitional actions or thoughts or kamma formations: Dependent on volitional actions or thoughts arises consciousness; where the consciousness is created, there exist mind and matter or mental physical phenomena and caused by them, arise spheres of senses (salāyatana) or faculties. Those faculties cause to contact and then get to sensation or feeling. Through feeling arise, desire thirst or craving (tanhā) Through craving arises grasping or clinging which leads to the process of Becoming where the concept of being exists. This existence of the concept of being is subjected to the concept of birth decay, illness and death etc.

One option is to neither believe nor disbelieve the actions of rebirth.

The very definition of belief is rooted firmly in the absence of fact. The same is true for a non-believer. Somewhere between the two lies a spacious void where one can remain open-minded about the notion of rebirth.

Personally, I shelved it precisely in this way. Two years later insight had occurred and not from books or other people. But still, I'm not able to prove it so it's neither here nor there. You'll have to find out for yourself. Wondering about it in this way may become huge hindrance to your practice. There's nothing wrong with entertaining your curiosity though if you keep the seriousness out of it.

Yes, it is. Without it the central concept of kamma would automatically and directly be baseless and meaningless. I would like to offer a down to earth explanation by means of an example from real life. If I am completely wrong, I will appreciate any downvotes and criticism.

If you go to a party, let's say, for clarity's sake, with a lot of your relatives. Let's say it's a wedding party, so conduct is at least somewhat expected. You might get drunk, let loose, and forgo self criticism. You might put up a show, make stupid jokes, hit on ladies that should not be hit on. If you are lucky, some other folks might do similar things while drunk, but especially if you were the only one to misbehave, then, when you wake up in the morning, and it all starts to come back, then it's that feeling that indicates that you have re-emerged (re-born) at a lower plane as a direct result the uncontrolled stupidity you commited during the night before — everyone saw and knew what you did would cause you suffering, but they didn't tell you because you wouldn't have listened, or they did and you didn't listen, so they waited until this very moment that you wake up alone here and now. I would say that is the phenomenon of telepathy. If now, you exit your bedroom and you still "don't remember", people will give you faces of a certain type which will ensure that you cannot ignore your "rebirth", most likely warm and friendly smiles (if they are good people).

And then you say to yourself: "damnit, karma..." (or, "damnit, kamma...", if you are a devout Pāli purist!). And you better go and apologise, and do something to compensate. As well as clean up the mess of your social suicide, after which you will have time to contemplate on the mess prior to the suicide which led you to it in the first place.

This example is easy to follow simply because it all happens very intensely and during a short period of time, and is made up of events of obvious meaning and ramifications, unlike long term deeds and fruits, the connections of which are harder to detect in everyday life — it's like in particle accelerators such as CERN, where everything that is normally slow (spread out in time and space), is made very intense (brought together in time and space), so as to "un-rare" certain normally rare events. You can generalize from the party and hangover example, just as scientists generalize from very intense high-speed collisions. So if for example a man for a long period in his life ignorantly/irresponsibly/uncompassionately, out of sheer sexual desire, sleeps with young easy to seduce drunk girls at parties, one day he will meet a child of one of such girls, who has had to grow up in a family where such a girl, now a mother, still has wounds or scars or emotional voids from such lifestyle, and the upbringing of that child will have been more difficult or lacking as a result. He/she will look you in the eye and something inside you tells you it was you who contributed to it, "in a previous life". Of course the girl/mother herself is at least as responsible obviously, and she might go through a similar rebirth once her child looks her in the eye after having met with such a man, and possibly having connected the ends at some point later in life.

If a person desn't believe in it — and I'm sure every person has experienced something like this first hand, unless perhaps he is Tarzan or Mowgly — then he obviously doesn't believe in reality, i.e. he is ignorant of it. And the Tathagata always teaches us about the reality.

Rebirth

Rebirth and death is momentarily. Each instance the material composition of your body changes, arising and passing away. Physical death is not different. See this answer, this answer and this answer.

How then can a Buddhist test this theory?

By doing Samatha meditation some people can develop memory of past lives. This way you can ascertain it. Also buy validating what you remember. Also there are studies like: Many Mansions: The Edgar Cayce Story on Reincarnation

Can one disregard this element of Buddhism? Is it an essential aspect of the philosophy?

This is an essential part. Each subatomic particle (Kalapas) arise and pass away. Main practice of Buddhism (vipassana) is to understand this at the experiential level.

And finally use this knowledge and insight at the moment or physical death to release oneself from the cycle of birth and death.

"Elements of Buddhism can be rationally accepted such as the suffering that arises through attachment, the benefits of meditation, and even the acceptance of anatta, or non-self. It seems, however, that a belief in rebirth cannot be accepted rationally."

Indeed, the Buddha described his Dhamma as "The Dhamma visible here & now". However, if that visibility were immediately accessible, we wouldn't have doubts about it, and it would not be necessary a "path" to help us "see it". So, knowledge and skills are necessary to develop understanding, just like knowledge and skills are necessary in sciences to "see" phenomena (e.g. whether the claim of climate change affected by humans is true or not).

In the same way, knowledge and skills are necessary to see past lives according to the Buddha.

"When my concentrated mind was thus purified, bright, unblemished, rid of imperfection, malleable, wieldy, steady, and attained to imperturbability, I directed it to knowledge of the recollection of past abodes. I recollected my manifold past abodes, that is, one birth, two births ... 'There I was so named, of such a clan, with such an appearance' ..."

-- MN 36

"A believer must suspend rationality to accept a theory that describes the migration of some level of consciousness across a lifetime."

One does not need to accept (believe) or reject a theory that one is unable to verify at the moment. One can simply be aware of the competing theories and strive to see which one, if any of them, is true.

In science something similar happens where researchers point out flaws or remaining questions that need to be answer (i.e. that need more research) before accepting a theory.

I find this similar to the way the Buddha taught as well (e.g. refer to the discourse of DN 1). Thus, generally speaking, it's better to try out methods to see the truth than to hold or cling to any view prematurely. Or, more than that:

Who is attached still enters into doctrinal debates, but one unattached, how could he take sides? For him nothing is taken up or put down, With all views shaken off, relying on none.

-- Snp 4.3

Finally, the idea of "what transmigrates" is an old and on going debate, as the Buddha explicitly denied that any substance transmigrates, which would make that very substance something that endures -- that is, a Self (see this question: Then where did the concept of “rebirth” come from?).

"A common analogy used is the light emitting from a candle. Nothing substantial transmigrates, however something passes over from one life to the next. This theory cannot be directly perceived. Therefore, it cannot be tested, or verified rationally. It is simply a metaphysical inference."

As explained above, the buddhist doctrine asserts this knowledge can be directly perceived without resorting to fragile or indirect means (like beliefs). So, in the context of buddhism, recalling past lives is as metaphysical and irrational as the idea of remembering what one did a few moments ago.

"Buddhism encourages debate and questioning of its theories, and to not accept everything on face value. How then can a Buddhist test this theory"

I'm not able to recall my past lives, so my knowledge is not rooted in practice, only in reading. The progression of meditative attainments the texts shows seem to indicate that one who has mastered the fourth jhana (samadhi practice) possess enough skills in concentration to direct his/her mind to memories of past lives. I've heard that one practice is to gradually recall childhood, infancy, even memories in the womb, and then, to the past life, and so on.

"Can one disregard this element of Buddhism? Is it an essential aspect of the philosophy?"

This question has been asked here: Is rebirth/reincarnation central to Buddhism?.

There is, though, a Secular Buddhism movement in the west which seem to, literaly, strip out a lot of things from Buddhism, including rebirth. Also, some buddhists who may not subscribe to this movement may also believe rebirth (as in dying and reappearing in another life) is not true or not part of what the Buddha taught.

KARMA IS ESSENTIAL TO BUDDHISM. Buddha said that if one doesn't believe in karma then it's wrong view. There are many proof for karma. You just need to look back into your life and remember all the bad things that you did and the similar bad experiences that you suffer.

If SN 12.2 together with SN 23.2, SN 5.10 & SN 22.81 are studied carefully, it appears what the Buddha actually taught about was "birth" ("jati") rather than "rebirth", which is not physical birth from the womb of a woman but instead the birth of the idea, view or mental concept of "beings" ("satta') or, more simply, "self".

Thus, the goal of Buddhism is to eradicate the birth of the "self" idea, i.e., eradicate attachment,i.e, realise not-self (anatta). The Alagaddupama Sutta states:

There is the case where a monk's conceit 'I am' is abandoned, its root destroyed, made like a palmyra stump, deprived of the conditions of development, not destined for future arising.

There is the case where a monk's wandering-on to birth, leading on to further-becoming, is abandoned, its root destroyed, made like a palmyra stump, deprived of the conditions of development, not destined for future arising.

It is obvious believing in post-mortem "rebirth" is not essential to Buddhism because many fully enlightened beings came into existence after the Buddha spoke his first three sermons and none of those three sermons mentioned "rebirth". Each of those sermons only mentioned the eradication of craving & self-view.

The Pali scriptures explicitly state that the dhamma of the Buddha is visible here-&-now & is to be verified by each wise person thus "rebirth" cannot fall into the dhamma of the Buddha.

The common analogy about the light emitting from a candle is not logical, which is why the Buddha never taught such an analogy. In Buddhism, only a later-day monk famed for teaching Greeks is known for such an analogy. This is because the light of the candle depends on the wick & wax. The light (flame) of a candle cannot move to a second candle if the first candle is devoid of wick & wax. Further, the first candle cannot even be lit without fuel from other source. This is why the Buddha taught consciousness cannot arise without a physical body & without sense organs & admonished a monk for teaching consciousness is reborn (refer to Mahatanhasankhaya Sutta & Upaya Sutta).

Buddhism originally criticized other religions that believed in unverifiable things (refer to Canki Sutta, Tevijja Sutta, Tittha Sutta, Bhūmija Sutta, etc) but later-day Buddhism over the years must have started to teach & write scriptures about unverifiable things.

The Pali scriptures themselves explain any belief about any kind of "rebirth" is not a factor of the noble eightfold path but is, instead, a polluted right view that sides with only morality (refer to Maha-cattarisaka Sutta).

From Ven. Bodhi's excellent short essay "Dhamma Without Rebirth?":

The aim of the Buddhist path is liberation from suffering, and the Buddha makes it abundantly clear that the suffering from which liberation is needed is the suffering of bondage to samsara, the round of repeated birth and death. To be sure, the Dhamma does have an aspect which is directly visible and personally verifiable. By direct inspection of our own experience we can see that sorrow, tension, fear and grief always arise from our greed, aversion and ignorance, and thus can be eliminated with the removal of those defilements. The importance of this directly visible side of Dhamma practice cannot be underestimated, as it serves to confirm our confidence in the liberating efficacy of the Buddhist path. However, to downplay the doctrine of rebirth and explain the entire import of the Dhamma as the amelioration of mental suffering through enhanced self-awareness is to deprive the Dhamma of those wider perspectives from which it derives its full breadth and profundity. By doing so one seriously risks reducing it in the end to little more than a sophisticated ancient system of humanistic psychotherapy.