Chapter Three opens with Arjuna's voice, not Krishna's. In the previous chapter, Krishna spoke at length about the glory of knowledge and wisdom. Arjuna heard all of it. And now a very natural doubt has risen in his mind: if knowledge is higher than action, why is Krishna asking him to plunge into the horror of battle?
The question is honest and direct. Arjuna addresses Krishna by two names here: Janardana and Keshava. Both are terms of deep affection and trust. He is not arguing. He is genuinely confused, like a student who has listened carefully to two different lessons and cannot see how they fit together.
Every spiritual seeker hits this fork at some point. Should I withdraw from the world and seek knowledge? Or should I stay in the thick of life and act? Arjuna's confusion is the doorway through which the entire teaching of Karma Yoga will now unfold.