The universal answer to this question is- Carefully. But how does one go about reasoning carefully? First, one must learn the primary tool of reasoning: Logic. Here we offer a glimpse of formal logic but move on to an alternative approach to formal logic. We argue that in real life context, an exhaustive knowledge of formal logic is rarely useful. Formal logic was, and still is, essential for studying computer science, mathematical proofs and epistemology. This section will explain some fundamentals of formal logic, but only to the extent which is necessary for one to understand the nature of logical structures.
On reasoning carefully, the next section on dialectic, we will take you through some helpful tools of thinking and rethinking.