This paper offers an account of collective epistemic vices, which we call the “group identification account”. The group identification account attributes collective epistemic vices to the groups that are constituted by “group identification”, which is a primitive and non-doxastic self-understanding as a group member (Turner, 1982; Brewer, 1991; Brewer & Gardner, 1996; Pacherie, 2013; Salice & Miyazono, 2020). The distinctive feature of the group identification account is that it enables us to attribute epistemic vices not just to established social groups (...) (e.g. committees, research teams, juries) but also to loose social groups (e.g. loosely connected people in an echo chamber) when they are constituted by group identification. The group identification account is contrasted with Fricker’s (2010, 2020) influential account, the “joint commitment account”, which focuses on established social groups, and has difficulty in making sense of collective epistemic vices of loose social groups. The group identification account is motivated by the fact that collective epistemic vices can be useful to diagnose not only the epistemic performance of established groups but also that of loose groups in real-life cases, such as echo chamber (Nguyen, 2020), implicit bias (Holroyd, 2020), group polarization (Broncano-Berrocal & Carter, 2021), etc. (shrink)