It is a bit funny: you attempt to show the irrelevance of philosophy, and immediately stumble on a deeply philosophical question: "What is the measure of philos

It is a bit funny: you attempt to show the irrelevance of philosophy, and immediately stumble on a deeply philosophical question: "What is the measure of philosophic truth?" Actually, the question is "what is the measure of truth?", because philosophy has no special rules about truth. Then you repeat the Sophist's answer, a philosophical school. Unfortunately for you, philosophy has much much more to say about truth than what the Sophists said. For example, they invented logic, and explained how to identify fallacies. So "just about rhetoric" has been shown to be wrong. This invalidates your argument 1. Your question in 2 is again deeply philosophical: when is any knowledge "good enough"? Go on and treat this question seriously, then you will find out that some philosophers did the same already, and that you might learn something from them.