The rationale behind the introduction of negative marking in UPSC exams is to discourage random guessing and encourage candidates to answer questions based on knowledge. This system aims to ensure that marks reflect genuine understanding rather than luck, promoting a higher standard of assessment. By penalizing incorrect answers, the examination becomes more competitive and fair, compelling candidates to focus on accuracy. It also encourages aspirants to prepare thoroughly, enhancing their overall preparation strategy, as solid knowledge becomes essential for scoring well.