Why did Krishna break the law of nature by giving life to a dead person?
Abhimanyu's son was supposed to continue the race as few boons were conferred in that way:
1. Boon to Soma by Gods or indeed demand by Soma:
[Soma to Gods:] And my son shall compel all foes to retreat before him. The boy of mighty arms having penetrated the impenetrable array, shall range within it fearlessly and send a fourth part of the hostile force, in course of half a day, unto the regions of the king of the dead. Then when numberless heroes and mighty car-warriors will return to the charge towards the close of the day, my boy of mighty arms, shall reappear before me. And he shall beget one heroic son in his line, who shall continue the almost extinct Bharata race.' Hearing these words of Soma, the dwellers in heaven replied, 'So be it.'
2. Boon by a Brahmin to Abhimanyu's wife
Vaishampayana said, "Understanding that that weapon was thrown (into the wombs of the Pandava women) by Drona's son of sinful deeds, Hrishikesha, with a cheerful heart, said these words unto him: ‘A certain brahmana of pious vows, beholding Virata's daughter who is now daughter-in-law to Arjuna, while she was at Upaplavya, said, "While the Kuru line will become extinct, a son will be born to thee. This thy son for that reason, will be called by the name of Parikshit."
3. The below is in conflict to above boons as Drona's son wanted to destroy the foetus
Unto Govinda, that foremost one of the Satvata race, while he was saying these words, Drona's son, filled with wrath, replied, saying, ‘This, O Keshava, that thou sayest from thy partiality for the Pandavas, shall not happen. O thou of eyes like lotus-petals, my words cannot but be fulfilled. Uplifted by me, this weapon of mine shall fall on the foetus that is in the womb of Virata's daughter, upon that foetus which thou, O Krishna, art desirous of protecting.'
So, it became an example of boon deadlock where
- one brahmana and gods gave a boon that a son will be born
- but another (Aswatthama) released brahmashira to kill the foetus itself so that son can't be born.
Many instances like this are mentioned in the Is there any mention of boon deadlock in scriptures? post where solution was like this
- first let the person die and then revive again to keep the truth of both the boons/curses/divyAstras
So, Lord Krishna handled the boon deadlock in this way:
The holy one said, "The fall of this mighty weapon will not be fruitless. The foetus will die. But being dead, it will live again and have a long life! As regards thyself, all wise men know thee for a coward and a sinful wretch! Always engaged in sinful acts, thou art the slayer of children. For this reason, thou must have to bear the fruit of these thy sins. For 3,000 years thou shalt wander over this earth, without a companion and without being able to talk with anyone. Alone and without anybody by thy side, thou shalt wander through diverse countries, O wretch, thou shalt have no place in the midst of men. The stench of pus and blood shall emanate from thee, and inaccessible forests and dreary moors shall be thy abode! Thou shalt wander over the Earth, O thou of sinful soul, with the weight of all diseases on thee. ~Mahabharata: Sauptika Parva: Section 16
Also, such acts were not considered against the nature. We have many instances (Resurrection stories in Hindu scriptures?) similar to this (when dead one's life was brought back):
Lord Shiva gave life to Ganesha after his head was severed (~Shiva Purana)
Lord Shiva gave life to Daksha after his head was severed (~Shiva Purana)
Sage Bhrigu gave life to his wife after her head was severed (~as discussed in this post)
Sage Bhrigu/Lorad Parshuram gave life to Jamadagni after his head was severed (~ as discussed in this post)
Each Pandava has one or more than one wife other than Draupadi and all of their sons were also killed in the war. But was it not possible for them to have more children again? What was the technical/medical/mythical/social problem for Pandavas to not reproduce more children?
As the boon was that Abhimanyu's son will continue the almost extinct Bharata race. So, there was no point of this question that why Pandavas could not produce other children.
Where can we find the description of how Maharaja Parikshith (as a baby) was saved by Sri Krishna?
Is there any mention of boon deadlock in scriptures?
Resurrection stories in Hindu scriptures?