Misunderstanding Convivial Solipsism: the Necessity of a Perspectival Logic

Convivial Solipsism is easily misunderstood. Because it denies the absoluteness of observed events while preserving the universality of quantum mechanics, it invites objections that are often formulated in a classical, non-perspectival language. Such objections appear powerful only because they smuggle back into the discussion the very assumptions that Convivial Solipsism rejects. This article reconstructs a family of misunderstandings that arise in discussions of Convivial Solipsism, especially in connection with Wigner's friend and extended Wigner's friend scenarios. The aim is not merely defensive. The objections are useful because they identify the conceptual discipline required by any interpretation that takes non-absolute facts seriously. The central claim is that observational facts must be indexed to perspectives. A statement such as "the friend saw outcome A" is not a complete factual statement within Convivial Solipsism. It must be reformulated as "from the friend's perspective, the friend saw outcome A" or "from Wigner's perspective, the friend reported outcome B." The mistake consists in removing these indices and then treating the resulting expressions as if they belonged to a single global factual domain. This leads to apparent contradictions and to false dilemmas concerning consciousness, communication, other minds, and intersubjectivity. When that is taken into account, it appears that Convivial Solipsism is not a retreat into psychological solipsism, but a discipline of perspectival discourse. It is also shown that perspectival logic stands to classical logic as the quantum calculus of probability stands to Kolmogorovian probability theory.