Krsna argues from the atheistic perspective (Bg 2.26 to 2.28)
After explaining the immortality of the soul. Krsna makes an additional point: even if one does not believe in the existence of the soul, there is still no reason to lament.
« The Song of God: An in-depth study of the Bhagavad-gītā (Volume 1)
Verse 26: atha cainam nitya-jātam, nityam vā manyase mṛtam
tathāpi tvam mahā-bāho, nainam śocitum arhasi
If, however, you think that the soul [or the symptoms of life] will always be born and die forever, you still have no reason to lament, O mighty-armed.
Verse 27: jātasya hi dhruvo mṛtyur, dhruvam janma mṛtasya ca
tasmād aparihārye ’rthe, na tvam śocitum arhasi
One who has taken his birth is sure to die, and after death one is sure to take birth again. Therefore, in the unavoidable discharge of your duty, you should not lament.
Verse 28: avyaktādīni bhūtāni, vyakta-madhyāni bhārata
avyakta-nidhanāny eva, tatra kā paridevanā
All created beings are unmanifest in their beginning, manifest in their interim state, and unmanifest again when annihilated. So what need is there for lamentation?
Up to verse 2.25, Krsna sustained his arguments on the idea of the immortality of the soul. In verse 2.26, he makes an additional point: even if one does not believe in the existence of the soul, there is still no reason to lament.
The idea that life comes from the combination of material elements and is lost forever with the destruction of the body (which is largely accepted in modern scientific circles) is not new. Even in antiquity, some philosophers thought in that way, like the Lokāyatikas and Vaibhāṣikas. These philosophies offer conclusions that are similar to classical Buddhism and also to the modern scientific view. However, Krsna argues that even if one believes that life appears just due to the combination of material elements, there is still no reason to lament, since in this case life would be ephemeral and ultimately without value or purpose. No one stops performing his duties due to fear of spoiling a small amount of chemicals. Another side of the argument is that if there is no soul, it means there is no afterlife, and no karma, therefore, Arjuna would have no reason to lament the death of his relatives. Krsna thus shows how the performance of duty is more important than petty considerations, both from the view of dharma and from the atheistic viewpoint.
The philosophy that most follow nowadays is not exactly atheism, but hedonism. Atheism is still based on some idea of personal and social progression or development, even though deprived of a clear understanding of God. Hedonism, on the other hand, is based just on selfishness and immediate satisfaction, resulting in the most complete type of degradation. Atheism still has a certain resemblance to rationality and certain goals, but hedonism is purely self-destructive. An atheist may still question the value and goals of life, which may create opportunities for receiving spiritual knowledge at a certain point, but in hedonism, there is just a cynical process of denial and justification that leads to a troubled and purposeless life, followed by degradation to lower forms of existence.
Examining the question from different sides, Krsna therefore frankly suggests that Arjuna should fight, fulfilling his duty instead of abandoning the battlefield and going to meditate in the forest as he had considered. This is also an important lesson for us since we have a similar tendency to use renunciation as an excuse to run away from problems. Renunciation is good when practiced with the right mentality, by someone without material desires, but false renunciation based on escapism or frustration does no good. One of the main secrets revealed in the Bhagavad-gītā is the art of engaging our natural propensities in Krsna's service. This is an art that can elevate us to a transcendental position, no matter what our starting point is.
Later in the Bhagavad-gītā, Krsna reveals that the message of the Bhagavad-gītā was transmitted before to kings and leaders of the society. A king is someone who can’t whimsically reject his duties. He is someone who has to forge his spiritual path while simultaneously dealing with all the complexities of running a kingdom and protecting the citizens. This is what makes the Bhagavad-gītā so useful for us: it teaches how one can become spiritually advanced even while dealing with all the complexities of modern life. The key is not in necessarily changing our place or occupation, but in changing our consciousness. If Arjuna could become self-realized while fighting in a war, certainly we also can, no matter how challenging our situation may be.
Krsna continues arguing from the point of view of analytical knowledge on verses 2.27 and 2.28, mentioning that one who has taken his birth is sure to die, and after death one is sure to take birth again, and that all created beings are unmanifest in their beginning, manifest in their interim state, and unmanifest again when annihilated. He thus makes the point of the inevitability of birth and death, something that is accepted by both theists and atheists. As it is popularly said, "as sure as death".
From the theistic viewpoint, once one dies, he will surely take another birth, and from the atheistic viewpoint, the matter that composes our bodies will continue existing in other forms. We can see that often, atheists find solace in the idea of their ashes being thrown into the ocean and thus merging into it, or having a tree planted over their buried bodies, so they can have the idea of merging into the tree and thus continuing to exist, etc. Krsna thus poses additional arguments to maintain His conclusion that whatever one believes or not in the existence of the soul, there is no reason to lament or fear death.
This point was surely relevant for Arjuna, since he was the one facing death on the battlefield, but it is also no less relevant for us. The point is that all of us face death and loss on a daily basis, even though not as dramatically as Arjuna, and this fear of death and loss may play a role in our decisions, just as it was playing in the case of Arjuna. The arguments Krsna offers in these verses are thus also relevant for us, and they serve as a foundation for the spirit of detachment that Krsna will try to inculcate into us in the following verses and chapters. One who truly understands this science becomes fearless.
Main points in the purports of Srila Prabhupada:
"If, however, you think that the soul [or the symptoms of life] will always be born and die forever, you still have no reason to lament, O mighty-armed."
a) Lokāyatikas and Vaibhāṣikas are ancient classes of philosophers who, similar to modern scientists, don't believe in the existence of the soul separate from the body. According to them, life comes from the combination of material elements.
b) In a war, many tons of chemicals are wasted to achieve victory, in the form of munitions and other military equipment. Therefore, if life comes from matter, what is the problem of wasting tons of chemicals in the form of material bodies? In this way, even if Arjuna accepted these atheistic philosophies, there was no reason to lament.
c) If there were no rebirth or continuation of the soul after death, Arjuna would also not have to fear sinful reactions for killing his relatives. In this way, Krsna argues that both from the side of Vedic understanding, or from the materialistic conclusio,n there was no need for Arjuna to lament in the performance of his duty.
d) Krsna calls Arjuna mahā-bāhu (mighty-armed) to emphasize that he was a follower of the Vedas, and therefore should perform his duty, following the principles of the scriptures.
"One who has taken his birth is sure to die, and after death one is sure to take birth again. Therefore, in the unavoidable discharge of your duty, you should not lament."
a) The fact that the soul goes from one body to the other does not support unnecessary murder, slaughter, and war. At the same time, violence is necessary to maintain law and order in society.
b) The Battle of Kurukṣetra was an inevitable event, and being a kṣatriya, Arjuna had a duty to perform. By neglecting his duty, he would break the law and become liable for the very sinful reactions he was afraid of. He would not be able to stop the death of his relatives and would be degraded for acting inappropriately.
"All created beings are unmanifest in their beginning, manifest in their interim state, and unmanifest again when annihilated. So what need is there for lamentation?"
a) Even if we accept the atheistic view that there is no soul, there is no cause for lamentation. The law of conservation of energy guarantees that all material elements remain; they just assume different forms. All bodies didn't exist in the past, they exist now, but will not exist in the future. Everything changes, and there is no way to stop it, therefore, there is no reason to lament. If life comes from matter, it means we are matter, and matter continues to exist in different forms. Since nothing is lost, and things are manifested for just a short time, life or death makes no material difference.
b) And, if we accept the Vedic conclusion, there is also no reason to lament, because the body is just a dress for the eternal soul. Because of its temporary nature, the body is just like a dream for the soul, something ephemeral.
c) Autough the body is not false, because it is temporary it is like it doesn't exist. Just as a dream is not false, but at the same time also not real. The body is thus called asat (nonexistent). The Vedas encourages self-realization based on the understanding of this nonexistence of the material body, contrasted with the eternity of the soul.
« The Song of God: An in-depth study of the Bhagavad-gītā (Volume 1)