I read that Sai Baba encourages argumentation and debate as a path to self-knowledge. Can you explain this philosophy?

The source material indicates the opposite of what you have read. In Chapter 2, it is stated that a mind inclined towards argumentation is filled with ignorance and Maya, not self-knowledge. Such a person is considered unfit for self-knowledge and is instead devoured by ignorance. Sai's guidance discourages establishing one's own side, refuting others, or engaging in dualistic explanations, labeling such efforts as useless. The text emphasizes that where there is devotion with faith, born from hearing and contemplating His stories, self-experience and bliss will naturally arise, leading to knowledge of one's true form.