There is always a persuasive component behind discussions related to social disputes, where rhetoric strategies are used intentionally and unintentionally. The quality of rhetoric debate can bring reflection and evaluation of democratic society. This study uses Aristotle’s three kinds of discourse to analyze the Facebook posts from the Kuomintang and the Democratic Progressive Party regarding the Ractopamine pig’s import controversy. We found that when facing social disputes, the two parties mostly use forensic discourse based on the evaluation of past events, focusing on accountability and conviction or counter-accusation and self-defense. They rarely use deliberative discourse, which proposes thoughtful arguments to influence future decisions, or epideictic discourse, which emphasizes shared understanding. When political posts on social media are flooded with forensic discourse, it is inconducive to public communication, and this phenomenon is worth reflecting on. This study hopes to rediscover the core values and new criteria of public discourse in a democratic society through the dissection of rhetoric and analysis of the process of social disputes.