I’ve been a science student for years and still am. I think the question here seems to be not so much related to the way we do scientific research to discover the laws of nature but existing scientific theories that are widely accepted not necessarily seemingly compatible to the description found in Pali Canon. That is, to assume we actually understand what is being said in the suttas.
Let’s clear up some misconceptions. Before we learn the existence of the law of kamma, we might think that living beings are born due to their parents. In fact, that’s the basis behind the theory of evolution, is it not? It’s undeniable that our physical body has inherited biological traits (as well as seemingly random changes) from our parents. Such understanding is also based on a tacit assumption, which is living being is defined purely by a system of “matters” which exhibits the “basic characteristics of living thing”. Such definition has some fundamental issues, such as “matter” itself is not well-defined within the realm of physics. In fact, in doing scientific research, they avoid talking what is matter at all because it could not be defined in any sensible ways.
Science neither denies nor recognizes the existence of consciousness, feeling, perception, and volitional formation. Through our experience, we one way or the other recognize their existence. But we do not really think of them as “part of the matters”, which does not seem to be the case at all. If we think somehow they are all “derived from matters”, which is based on nothing other than pure guess.
Recognizing plants and bacteria are living things, but it’s puzzling that they do not seem to exhibit any traits of consciousness, unlike animals or human beings. Because they do not have a “nerve system”. Even if you are not a scientist, you should more or less recognize science itself, which particularly deals with “matters”, could not explain anything that is beyond its scope of study. In a way of speaking, the very definition of science and scientific research limits what can be found out from scientific research.
The missing part of the understanding of sentient beings in biology, which do exhibit consciousness, is the fact that they all exhibit consciousness. Does psychology give us the answer? That does not seem to be the case. At best, its study gives us some hints to deal with what we perceive as “mental illness”.
In a way of speaking, it’s not wrong to say cylindrical shape when a blind person only touches the leg of an elephant; but it is not the shape of the entire elephant, is it?
Unlike scientists, Buddha did not attempt to explain the natural phenomena. When he did seemingly describe them, it’s meant for a greater purpose of understanding the four noble truths or “dependent origination”.
The very idea that we can say the “physical body” is truly “mine” or represent “me” as a “being” is wrong view. Obviously, the corpse is not a living thing. We may have thought we temporarily “own” the physical body as living beings. However, the thing that we think we own is always subject to change; so what we perceive we “own” no longer exists? Or, its very own existence is subject to changing conditions, which we have no control whatsoever. That is the truth which cannot be denied by somebody who is non-delusional.
Buddha said about the “four great elements”, namely “earth, fire, air, water”. But if you think of them as chemical elements, if you have clearly misunderstood what Buddha meant. Even though it sounds similar to the old-school teaching in ancient Indian philosophies, Buddha merely borrowed the terms to describe something. You may perceive the physical body consists of parts that exhibit different characteristics, such as solid, liquid, energy, and gas. Such a fact is directly observable. What Buddha tried to tell is that this physical body is derived from “elements” which themselves are impermanent and lack of self, which explains why it’s impermanent and also lack of self. At the fundamental level, some elementary particle such as electron seemingly has very long half-life. But with an anti-particle, the can “disappear” which gives rise to a pair of photons. Their behavior is also dependent on conditions, such as electromagnetic force, gravitational field, strong interaction, or weak interaction.
Sentient beings would not be sentient beings without consciousness, feeling, perception, and volitional formations. But consciousness, at least in the realm of sense, does rely on physical body. They are different but also dependent on each other. When this physical body breaks up, consciousness can exhibit itself in another physical body. This in itself is not disputable. This however, does not mean a “soul” has been transferred from one body to another.
The validity of a scientific theory relies on the validity of the assumption. Our live begin with birth and end with death. However, kamma extends beyond a single life. The understanding of four noble truth cannot be found by understanding physical laws itself. Our suffering is not necessarily within the scope of natural science.
One way of determining death of a sentient being is to see that consciousness ceases from a physical body. Within medical science, they usually rely on determining the condition of some organs, such as heart, brain… They cannot prove or disprove the existence of consciousness through empirical evidence, can they?
Alternatively, birth can also be understood as the arising of consciousness in a physical body, as a reverse of death. In this way, we do not deny that our physical body does come from the growth of zygote which is formed by combination a “sperm” and an “egg”. But does either of them exhibit consciousness? From biology, we understood that our consciousness requires the work of brain. If such understanding is taken to be correct, then we must accept neither sperm nor egg exhibits consciousness as brain does not exist yet.
As if it is not already obvious biology has left out a large part of what think of ourselves. I am not here to say that science is not useful. But we need to understand science and its scope before again falling into wrong view.
Contrary to popular belief, “Kamma” is not a moral law even though producing good kamma does seem to be fit in the definition of living a moral life. The understanding of kamma requires the understanding something which is much difficult to understand, dependent origination. The “Stream-Enterer” is said to gain “Dhamma Eye”, but he has not rooted out ignorance. A “stream-enterer” has understood thus gained unwavering confidence to Buddha, Sangha, Dhamma and abandoned “identity view”. He is still clinging to the “identity view” even when he recognizes such view is fundamentally wrong. Only a fully-enlightened being, an arahant, with or without the knowledge of the details of previous lives, has true knowledge of “dependent origination” and “four noble truth”.
Contrary to widespread misconception, meditation does not lead to the perpetual cessation of craving; it does help suppress the craving temporarily, which somebody calls it “temporary liberation”. If craving has not been rooted out, human being would inevitably desire for sex; thus it not contradictory that psychology may call that “sex” is a basic necessity. Only a fully enlightened being, an arahant has rooted out craving completely. Any study being done over human beings will inevitably shows human being desires for sex, which is exactly what Buddha says.
“When craving arises, clinging arises; when clinging arises, existence arises; when existence arises, birth arises; when birth arises, aging and death arises.”