Generally, Buddhists believe that there is no beginning to birth and that once we achieve liberation from the cycle of existence by overcoming our karma and destructive emotions, we will not be reborn under the sway of these conditions. Therefore, Buddhists believe that there is an end to being reborn as a result of karma and destructive emotions, but most Buddhist philosophical schools do not accept that the mind-stream comes to an end. To reject past and future rebirth would contradict the Buddhist concept of the ground, path and result, which must be explained on the basis of the disciplined or undisciplined mind. If we accept this argument, logically, we would also have to accept that the world and its inhabitants come about without causes and conditions. Therefore, as long as you are a Buddhist, it is necessary to accept past and future rebirth.
For those who remember their past lives, rebirth is a clear experience. However, most ordinary beings forget their past lives as they go through the process of death, intermediate state and rebirth. As past and future rebirths are slightly obscure to them, we need to use evidence-based logic to prove past and future rebirths to them.
To reject past and future rebirth would contradict the Buddhist concept of the ground, path and result, which must be explained on the basis of the disciplined or undisciplined mind. If we accept this argument, logically, we would also have to accept that the world and its inhabitants come about without causes and conditions. Therefore, as long as you are a Buddhist, it is necessary to accept past and future rebirth.
The world and its inhabitants come about through the forces, impacts, chemicals, etc, of biological reproduction. The law of kamma is about psychology rather than biology.
There are many different logical arguments given in the words of the Buddha and subsequent commentaries to prove the existence of past and future lives. In brief, they come down to four points: the logic that things are preceded by things of a similar type, the logic that things are preceded by a substantial cause, the logic that the mind has gained familiarity with things in the past, and the logic of having gained experience of things in the past.
In DN 16, it is reported the Buddha said his true disciples, when adverse opinions arise, they shall be able to refute them thoroughly and well, and to preach this convincing and liberating Dhamma. Also, in AN 2.23, it is reported the Buddha described as 'slander' as 'what was not said or spoken by the Tathagata as said or spoken by the Tathagata'.Also, in AN 3.65, it is said 'logic' is not to be used for a ground of belief. It follows the Buddha never said all things are preceded by things of a similar type & all things are preceded by a substantial cause. There is the famous verse by Asajji to Upatissa (Sariputta), that said:
"Of all those things that from a cause arise,Tathagata the cause thereof has told;
Therefore, all things do not arise from a cause. Only certain things arise from a cause.About consciousness, for example, the Buddha said it only exists based on condition (paccaya) and not cause (hetu).
'Apart from a requisite condition, there is no coming-into-play of consciousness' (aññatra paccayā natthi viññāṇassa sambhavo)
Similarly, about ignorance, the Buddha said it exits due to nutrient (ahara) but not due a cause (hetu).
(AN 10.61 ) "A first beginning of ignorance cannot be conceived, (of which it can be said), 'Before that, there was no ignorance and it came to be after that.' Though this is so, monks, yet a specific condition of ignorance can be conceived. Ignorance, too, has its nutriment, I declare; and it is not without a nutriment. And what is the nutriment of ignorance? 'The five hindrances,' should be the answer.
The difference between a 'cause' (hetu) & a 'condition' (paccaya) or 'nutriment' (ahara) is a cause is a preceding condition (example, the cause of decay is bacteria or the cause of craving is feeling) where as a condition or nutriment can act in assocation with the something. In Dependent Origination, for example, the Buddha used the word 'paccaya' since ignorance & sankhara do not create or cause consciousness (in the way batteries cause light in a torch) but, instead ignorance & sankhara condition or influence consciousness to be in a certain way (such as preoccupied, unclear or agitated). Therefore, the Buddha never explained what the causes of consciousness, ignorance, craving for existence, Nibbana, the four great elements, etc, were because these are unknowable. In MN 64, the Buddha taught a new born child has an underlying tendency for defilements but not a 'familiarity' towards things. For example, why certain disciples were attracted to certain arahant teachers the Buddha attributed solely 'elements' (SN 15.14). In MN 12, the Buddha said:
13. (4) "Again, the Tathagata understands as it actually is the world with its many and different elements. That too is a Tathagata's power...14. (5) "Again, the Tathagata understands as it actually is how beings have different inclinations. That too is a Tathagata's power..
In AN 1.49, it is said clarity is clouded by defilements and illuminated by the ending of defilements. It is not said clarity comes from clarity.
In Thailand, there was a famous monk named Ajahn Chah, reputed to have psychic powers & be an arahant. Yet in old age, Ajahn Chah developed dementia (or similar) and became unconscious. In other words, the mind no longer had clarity & awareness (at least externally). Therefore, it appears obvious, just as electricity or fire powers light, the electrical neurons of the brain (or some other physical cause) powers the light of consciousness and, when the brain malfunctions or ages, so does clarity. In MN 18 and elsewhere, the Buddha explained the arising of clarity & awareness (aka 'consciousness') is dependent on sense organs & sense objects. For example, in the cessation of perception & feeling, because consciousness no longer has any sense objects (namely, perception & feeling), it becomes unconscious. That is why in SN 22.53 it is said for there to be the arising of consciousness without the other aggregates is impossible. In DN 16, it is reported the Buddha said his true disciples, when adverse opinions arise, they shall be able to refute them thoroughly and well, and to preach this convincing and liberating Dhamma.
Ultimately all these arguments are based on the idea that the nature of the mind, its clarity and awareness, must have clarity and awareness as its substantial cause. It cannot have any other entity such as an inanimate object as its substantial cause. This is self-evident. Through logical analysis we infer that a new stream of clarity and awareness cannot come about without causes or from unrelated causes. While we observe that mind cannot be produced in a laboratory, we also infer that nothing can eliminate the continuity of subtle clarity and awareness