This article formulates five relative systems to evaluate the charge of self-refutation with regard to global relativism. It is demonstrated that all five of these systems support models with at least one thoroughly relativistic perspective. However, when these systems are extended to include an operator expressing the valuation of statements in a perspective, only one relative system, based on a nonnormal modal logic, supports a thoroughly relativistic perspective.
"Thoroughly Relativistic Perspectives." Notre Dame J. Formal Logic 53 (1) 89 - 112, 2012. https://doi.org/10.1215/00294527-1626545