Logical / Scriptural arguments: Prajna vada and Veda vada

 अशोच्यानन्वशोचस्त्वं प्रज्ञावादांश्च भाषसे।

गतासूनगतासूंश्च नानुशोचन्ति पण्डिताः॥ गीत २-११॥

Shradda (dedication), Meda (capacity to retain learnings in memory), Prajna (logic / discrimination capacity), Pratibha (innovativeness) and Dhruti (intellectual and emotional balance) are the five dimensions of Dhi. Unfortunately, Partha has lost his intellectual and emotional balance (Dhruti) and then trying to hide it using logical arguments (Prajna vada). Though logical reasoning appears to be coming out of clear thinking, it has its own limitations and may not always lead us to truth. Any logic used at a given point of time would be conditioned by past partial experience, present confusion and future anticipation. Hence, it cannot be unconditional, leading to truth always. Bhratrhari, a famous Sanskrit philosopher explains this in his Vākyapadīya saying, any logic by a sharpest mind can always be countered by a similar logic by another sharpest mind and there would be no end to it. An example for such a misplaced logic could be an argument for not removing weeds in a farm saying they too have right to live and grow. Logic of Communism: which believes in the theory of struggle between "Haves" and "Have-nots", ultimately leading to an ideal society where everybody is equal. However, history of Lenin, Stalin, Mussolini, Hitler etc. clearly demonstrates the consequences of such misplaced logic. A more workable and time tested Solution is dharma to achieve harmony in the society, where an affluent person would take care of "Have-nots" and in turn "Have-nots" would follow their duties such that, dharma is upheld in both cases, Pangu-Andha nyaya, rule of a blind person and a person without leg, both can move ahead by coming together. Hence, Krishna is advising Arjuna not to fall trap to such misplaced logic (Prajna vada) and grieve for unnecessary things.

यामिमां पुष्पितां वाचं प्रवदन्त्यविपश्चितः।

वेदवादरताः पार्थ नान्यदस्तीति वादिनः॥गीत २-४२॥

While, Prajna vada is using misplaced logic to defend hidden agenda or weaknesses, Veda vada is another strategy which people adopt, meaning to quote scriptural references to defend their weakness. One such example could be a person quoting Gita for Bhasma dharana, another example could be the blind following of scriptures given by Jesus, Mosses or Muhammad leading to indiscriminate massacring of people. Such Veda vadins would mostly be driven by consumerism and utilitarian thinking, using scriptures for their personal gains, they would not differentiate between good and bad as long as their personal interests are meet (Ramaya swasti, Ravanaya swasti), best way to describe them, showy, noisy, religious, quotation pandits. 

बुद्दियुक्तो जहातीह उभे सुकृतदुष्कृते।

तस्माद्योगाय युज्यस्व योगः कर्मसु कौशलम् ॥गीत २-५०॥

Krishna advises us to avoid both these extremes and instead, adopt Buddhi yoga to handle situations. Buddhi Yoga would convert, Karma to Karma yoga, any religious activity to an act of spiritual growth.