A significant share of political discourse occurs online on social media platforms. Policymakers and researchers try to understand the role of social media design in shaping the quality of political discourse around the globe. In the past decades, scholarship on political discourse theory has produced distinct characteristics of different types of prominent political rhetoric such as deliberative, civic, or demagogic discourse. This study investigates the relationship between social media reaction mechanisms (i.e., upvotes, downvotes) and political rhetoric in user discussions by engaging in an in-depth conceptual analysis of political discourse theory. First, we analyze 155 million user comments in 55 political subforums on Reddit between 2010 and 2018 to explore whether users' style of political discussion aligns with the essential components of deliberative, civic, and demagogic discourse. Second, we perform a quantitative study that combines confirmatory factor analysis with difference in differences models to explore whether different reaction mechanism schemes (e.g., upvotes only, upvotes and downvotes, no reaction mechanisms) correspond with political user discussion that is more or less characteristic of deliberative, civic, or demagogic discourse. We produce three main takeaways. First, despite being "ideal constructs of political rhetoric," we find that political discourse theories describe political discussions on Reddit to a large extent. Second, we find that discussions in subforums with only upvotes, or both up- and downvotes are associated with user discourse that is more deliberate and civic. Third, social media discussions are most demagogic in subreddits with no reaction mechanisms at all. These findings offer valuable contributions for ongoing policy discussions on the relationship between social media interface design and respectful political discussion among users.

翻译：政治话语很大一部分发生在社交媒体平台上。政策制定者和研究人员试图理解社交媒体设计在塑造全球政治话语质量中的作用。过去几十年，政治话语理论研究已梳理出不同类型突出政治修辞的独特特征，例如审议型、公民型或煽动型话语。本研究通过对政治话语理论进行深入概念分析，探讨社交媒体反应机制（即点赞、点踩）与用户讨论中政治修辞之间的关系。首先，我们分析了2010年至2018年间Reddit上55个政治子论坛中的1.55亿条用户评论，探究用户政治讨论风格是否与审议型、公民型和煽动型话语的基本要素一致。其次，我们进行了一项定量研究，结合验证性因子分析与双重差分模型，探讨不同的反应机制方案（例如仅点赞、点赞与点踩并存、无反应机制）是否对应着更具或更少审议型、公民型或煽动型话语特征的政治用户讨论。我们得出三个主要结论。第一，尽管政治话语理论是“政治修辞的理想构念”，但我们发现这些理论在很大程度上描述了Reddit上的政治讨论。第二，我们发现仅有点赞或同时有点赞和点踩的子论坛中的讨论，与更具审议性和公民性的用户话语相关。第三，社交媒体讨论在完全没有反应机制的subreddit中最具煽动性。这些发现为当前关于社交媒体界面设计与用户之间相互尊重的政治讨论之间关系的政策讨论提供了宝贵贡献。