The goal of the Five Whys is to land on a "what" or "how". It is not about introspection, such as "Why do I feel like this?" Rather, it is about systematically delving further into a statement or concept so that you can separate reliable knowledge from assumption. If your "whys" result in a statement of falsifiable fact, you have hit a first principle. If they end up with a "because I said so" or "it just is", you know you have landed on an assumption that may be based on popular opinion, cultural myth, or dogma. These are not first principles.