Any Discussion about Yoga Philosophy should have certain components. The first and primary should be an understanding, however cursory, of Patanjali's Yoga Sutras. In addition, exposure to The Bhagavad Gita is useful. From there, a discussion can take place that has something of a foundation. Whether it be an informal discussion of these two texts, or an actual study of the text with a qualified teacher, being aware of the roots of the yoga tradition can make a huge difference when it comes to understanding the why and what of Yoga.