UPSC evaluates a candidate's critical analysis of socio-political issues through their answer writing in the Mains Examination. Candidates must demonstrate analytical thinking, coherence in arguments, and a comprehensive understanding of current affairs and historical contexts. Papers often include case studies and real-life scenarios that require integration of knowledge to develop informed opinions. Evaluation criteria also focus on clarity of expression, relevance, and depth of insight, showcasing how well candidates can synthesize information and articulate a point of view on complex socio-political challenges.