On the contrary, the question you ask as absolutely impossible to answer in any kind of absolute way. All you can do is adopt an approach to answering it. You make choices about what you are going to consider a valid argument. If you decide that you will employ logic, testable rules, and the simplest possible set of axioms (like things are what they appear to be, laws don't change, theories tested at discrete points extend smoothly to the interstices over which they have not been tested, etc.), then you are using a scientific approach. This choice has other merits beyond being an intellectual gain-- witness the benefits that have accrued from using this approach. Nevertheless, it is far from a unique perspective, and benefits may also accrue from other approaches. The key point in all this is, the answer to a question is never separable from the method that was used to find that answer, and the criteria that is applied for ascertaining the "correctness" of any given answer. I'm afraid you simply cannot get around that. We'd all like to believe in absolute truth-- there's no such thing.