Researching ancient history of India is very exciting and challenging. It is exciting because great evidence in coming to light from areas of Astronomy, Geology, Archeology, Genetics, ancient narratives, and even from notorious discipline (notorious for twisting, torturing and manipulating evidence to achieve less-enlightened ends) linguistics.
One area of evidence that is often overlooked is that of ‘traditional knowledge’. This includes beliefs, among practicing Hindus, for celebrating memory of ancient events on specific lunar days of the year. This traditional knowledge can be extremely useful. However one should take care to treat it as a hypothesis (conjecture) and not as established evidence. This means, we can begin with traditionally assigned date (lunar date) for a specific incident as our ‘seed point’ – plausible date. But we cannot stop here (unfortunately many researchers do). We should test such plausible date against the available evidence to eliminate contradictions.
A specific example may make this point clear.
Gita-Jayanti (celebrating day when Krishna told Bhagavad-Gita to Arjuna, for the first time) is celebrated on Margashirsha Shudda 11 (Ekadashi).
Bhishma Ekadashi (celebrating day when Bhishma narrated Vishnu-Sahastranama to Yudhishthir, while lying on the bed of arrows) is celebrated on Magha Shudda 11 (Ekadashi).
Both events are from Mahabharata, longest epic of humankind. These two events take place separated by 2 lunar months (Margashirsha Shudda Ekadashi to Magha Shuddha Ekadashi, with Pausha Shudda Ekadashi as the midpoint).
Group of Mahabharata researchers (Ketkar, Achar, Raghavan, etc.) presume Margashirsha Shudda 11 (Ekadashi) as the first day of Mahabharata War. Celebration of Gita-Jayanti on this very lunar day certainly corroborates such belief. However, any decent student of Mahabharata would recognize that the corroboration ends there. This is because Mahabharata text furnishes us with at least 30 observations that specifically talk phases and positions of the moon during the 18 days of the War, and this set of evidence alone falsifies any claim for the first day of Mahabharata war that claims that day to be any day other than Amawasya ( New moon day).
Ok, so Mahabharata evidence related to positions and phases of the moon is against Margashirsha Shudda 11. What else goes against Margashirsha Shudda 11 as the first day of War, and thus traditional belief of Gita-Jayanti = Margashirsha Shudda 11.
Answer: A lot.
Let’s look at the second traditional belief mentioned above, i.e. Bhishma Ekadashi (Magha Shudda 11).
And what is the problem with this traditional belief?
Mahabharata text has 23 distinct chronological observations related to Bhishma-Nirvana and one of these observations point to Bhishma being on the bed of arrows for only 58 days. Another observation from this set of 23, points to the day of Bhishma Nirvana as that of Magha Shudda 8!
Group of Mahabharata researchers mentioned above (Ketkar, Achar, Raghavan) and also many others blindly accept the following facts:
(1) War began on Margashirsha Shuddha 11 (Ekadashi)
(2) Bhishma fell in the war on the 10th day of the War
(3) Bhishma was lying on the bed of arrows for 58 days.
(4) Bhishma-Nirvana occurred on Magha Shudda 8 (Ashtami)
These researchers, conveniently, sideline the issues of ‘counting of days’. We will do it for them.
According to their proposal,
Bhishma fell in the War on Margashirsha Krishna 5 (Krishna Panchami, 10 days after Shudda Ekadashi)
Counting from Margashirsha Krishna 5, we get 48 days until Magha Shudda 8, AND NOT 58 DAYS.
Not to forget the conflict with second traditional belief of Bhisham Ekadashi. According to these researchers or those who accept Gita-Jayanti = Margashirsha Shudda 11, Bhishma was not around to narrate ‘Vishnu-Sahastranma’ to Yudshishthir on Magha Shudda 11.
We have two traditional beliefs: Gita-Jayanti and Bhishma Ekadashi
I have shown above that evidence within Mahabharata text contradicts (and falsifies) Gita-Jayanti = Margashirsha Shudda 11.
And if one insists on this traditional belief at the cost of ignoring Mahabharata evidence (remember, there is no evidence for Geeta-Jayanati = Margashirsha Shudda 11, however Bhagvad-Gita is very much part of Mahabharata), it still conflicts with another traditional belief: Bhishma Ekadashi = Magha Shudda 11