कथं न ज्ञेयमस्माभिः पापादस्मान्निवर्तितुम्।कुलक्षयकृतं दोषं प्रपश्यद्भिर्जनार्दन॥
kathaṃ na jñeyam asmābhiḥ pāpād asmān nivartitumkula-kṣaya-kṛtaṃ doṣaṃ prapaśyadbhir janārdana
Word by word
The verse says
— why should we not know better than to turn back from this crime, Krishna, we who do see the fault in destroying a family?
In plain words
They cannot see it, he says. We can. So we should stop.
On its face this is decent. If you understand the harm and they do not, more is asked of you.
But look at where he has ended up. He began by saying his hands were shaking. He is now explaining that he is better informed than the enemy.
Where you've felt this · in study
In a long dispute, the moment you start saying I'm the only one here who can see what this is doing to everyone. It might even be accurate. It is also the point at which you stopped being in the argument and started standing above it.
Going deeper
Knowing more is not the same as being able to act, and Arjuna has quietly swapped one for the other.
His case now rests on superior sight: they are blind, we are not, therefore we must withdraw. But nothing in that follows. Seeing the cost of an action tells you what it will cost. It does not tell you whether to do it.
This is a distinction the Gita cares about a great deal. Knowledge and action are treated as two different paths in Chapters 3 to 5, and one of Krishna's steadiest points is that understanding something does not discharge you from having to act. Arjuna is using his clear sight as a place to stand still.
And this is the last verse in which he reasons for himself. From the next one he begins reciting, and by verse 44 he will say so outright.