This document provides an overview of methods for determining the truth or validity of claims through philosophical inquiry. It discusses how ancient Greek philosophers approached truth by examining the nature of knowledge and how we know what we know. It emphasizes employing systematic doubt to scrutinize all statements and determine truth, rather than taking anything as true without sufficient evidence. The document also differentiates between knowledge, facts, claims, opinions, arguments, beliefs, conclusions, explanations, and fallacies. It stresses that arguments may be based on faulty reasoning and fallacies, misleading the reader, so it is important to consider the characteristics and types of fallacies.