 General concepts and theories developed in other areas of social ontology have the potential to shed further light on collective memory. For example, the literature on collective intentionality (Tollefsen 2006), may clarify the activity of joint reminiscing, which might be understood as a form of joint attention to the past (Hoerl &amp; McCormack 2005; Seemann forthcoming). By providing a novel test case, collective memory also has the potential to shed light on general concepts and theories in social ontology. For example, Smith (2014) has pointed out that, whereas many social objects (institutions, contracts, and the like) are continuants, in the sense that they endure over time, the speech acts which, on many accounts, ground their existence, are events and hence exist only at a given moment in time. It is unclear how events might ground the existence of continuants, and one potential solution to this problem is to ground the existence of social objects not in speech acts but rather in forms of external memory, which are themselves continuants (Ferraris [2010] 2013, 2015).