Social presence theory has been a seminal part of digital pedagogies literature since the early generation of computer-mediated communication (CMC). However, despite multiple generations of the development of the theory, there is still a lack of a stable, widely accepted definition. Definitions range from those that identify social presence based on media affordances and attributes to those that identify social presence as a phenomenal state that is experienced by participants. This paper outlines the history and evolution of social presence definitions and their corresponding measures. It concludes that the factors that contribute to social presence should be identified in a non-mediated setting, as a psychological construct, in order to stabilize the definition, which would then provide a more stable definition that could lead to more accurate measurement across environments, both mediated and non-mediated.