Although the last decade has seen a proliferation of ontological approaches to arguments, many of them employ ad hoc solutions to representing arguments, lack interoperability with other ontologies, or cover arguments only as part of a broader approach to evidence. To provide a better ontological representation of arguments, we present the Arguments Ontology (ArgO), a small ontology for arguments that is designed to be imported and easily extended by researchers who work in different upper-level ontology frameworks, different logics, and different (...) approaches to argument evaluation. Unlike most ontological approaches to arguments, ArgO utilizes Basic Formal Ontology (BFO) as an upper-level ontology, and may be used alongside other commonly used ontologies in the BFO framework, including boththe Information Artifact Ontology (IAO), and the Information Entity Ontology (INFO). Critically, our proposal is principled, based on rigorous definitions and formal axioms out of which characterizations of arguments naturally fall. It is our hope that ArgO may assist researchers in many projects, including: integrating heterogeneous sources of evidence, structuring the content of semantic wikis, and enhancing semantic reasoning. (shrink)