David Lewis is widely regarded as the philosopher who introduced the concept of common knowledge. His account of common knowledge differs greatly from most later accounts in philosophy and economy, with the central notion of his theory being ‘having reason to believe’ rather than ‘knowledge’. Unfortunately, Lewis’s account is rather informal, and the argument has a few gaps. This paper assesses two major attempts to formalise Lewis’s account and argues that these formalisations are missing a crucial aspect of this account. Therefore, a new reconstruction is proposed, which explicitly discusses ‘reasons’ and uses a logic inspired by justification logic.

中文翻译：

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有理推理：刘易斯论常识

大卫·刘易斯被广泛认为是引入常识概念的哲学家。他对常识的解释与大多数后来的哲学和经济学解释有很大不同，他的理论的核心概念是“有理由相信”而不是“知识”。不幸的是，刘易斯的叙述相当非正式，而且论证也存在一些空白。本文评估了将刘易斯的叙述形式化的两次主要尝试，并认为这些形式化忽略了该叙述的一个关键方面。因此，提出了一种新的重构，它明确地讨论了“原因”并使用了受正当性逻辑启发的逻辑。