Defining critical security studies can be difficult due to the wide range of theories involved, meaning that any single definition is likely to exclude works and scholars who would list themselves, or be listed by most scholars as part of the subfield.
Browning and McDonald argue that critical security studies entails three main components: the first is a rejection of conventional (particularly realist) approaches to security, rejecting or critiquing the theories, epistemology, and implications of realism, such as the total focus on the role of the state when approaching questions of security.
The third component, is that of critically examining the ethics and approaches inherent to the study of security.
[5] More recent topics of concern include environmental and planetary, health, ontological, border or everyday security.
[7] The authors representing this latter view, such as Ken Booth and Richard Wyn Jones, are usually referred to as the Aberystwyth or Welsh School to avoid ambiguity.