ABSTRACT
Much of Charles S. Peirce’s philosophy hinges on his “universal categories” of Firstness (qualities, potentialities), Secondness (action, otherness) and Thirdness (relationship, rule-boundedness). Despite their abstractness, the categories have concrete applications and shed light on several critical realist theories, such as its ontological domains, its social ontology and its more nascent semiotics. Using Peirce’s categories this way requires building on his effectively non-deterministic materialist arguments and extricating his ontology from his better-known phenomenology. Peirce’s universal categories, which are stratified and emergent, unearth a systematic pattern unifying critical realist ontologies and address certain problems elsewhere in critical realist philosophy. Most significantly, Peirce’s semiotics provides critical realism with the mechanism connecting epistemology to ontology and grounds a case for reconceptualizing critical realism’s empirical domain as the semiosic domain.