On the Modal Nature of St. Anselm's Argument. Remarks on Andrzej Biłat's Paper Modal Logic vs Ontological Argument

Abstract

The paper examines the justification of two theses put forward in the article Modal Logic vs Ontological Argument by Andrzej Biłat: (1) the Anselmian ontological argument does not essentially engage modalities, and its force is not dependent on any specific logical modal laws (but only on classical logic); (2) the only source of modal force of the ontological proof is the Leibnizian theory of perfections. Biłat considers Hartshorne's version of the ontological proof and proposes his own formalization based on classical logic alone. We compare the presented theories and their formal background. We follow the proposed justification of Biłat's main opinion, point out its problematic (and not valid) fragments, and discuss its formal and material correctness. In conclusion, we consider the known possibilities of nontrivial application of modal logics to the analysis of St. Anselm's argument and some of its modern versions.