Social media platforms are rich sources of opinionated content. Stance detection allows the automatic extraction of users' opinions on various topics from such content. We focus on zero-shot stance detection, where the model's success relies on (a) having knowledge about the target topic; and (b) learning general reasoning strategies that can be employed for new topics. We present Stance Reasoner, an approach to zero-shot stance detection on social media that leverages explicit reasoning over background knowledge to guide the model's inference about the document's stance on a target. Specifically, our method uses a pre-trained language model as a source of world knowledge, with the chain-of-thought in-context learning approach to generate intermediate reasoning steps. Stance Reasoner outperforms the current state-of-the-art models on 3 Twitter datasets, including fully supervised models. It can better generalize across targets, while at the same time providing explicit and interpretable explanations for its predictions.

通过利用事前训练语言模型作为世界知识源，利用推理过程生成中间推理步骤的链式思维上下文学习方法，Stance Reasoner在社交媒体上的零样本立场检测方面优于现有技术，包括完全监督模型，并且能够更好地推广到不同的目标，并提供明确且可解释的解释其预测。

立场推理器：在社交媒体上的零样本立场检测与明确推理