Security is the key notion in the new discipline of security sciences. This term is a subject-matter category and refers to various social life participants, starting from an individual through large social groups, including organizational structures (institutions) representing single people and various social groups (states, nations, societies, international systems). Security is an existential need, i.e. connected with a particular individual’s existence. This need has a complex character and involves fulfilling such detailed needs as existence (survival/self-preservation), entirety, identity, independence, peace, possession and certainty of functioning and development. In the most general meaning, security may be defined as certainty of existence, possession, functioning and development of a subject. This certainty results not only from the lack of threat (it does not appear or is eliminated) but it also arises due to creative activity of a given subject and it changes with time, thus it shows the nature of a social process. Three dimensions of security can be differentiated: referring to the subject, object and functioning (process). Thus in the dimension referring to the subject, security means the certainty of existence and survival for a particular social life participant. In the dimension referring to the object it means the certainty of its possession status (identity including) and opportunities (freedoms) of development. In the functional dimension, security involves changing in time subjective and objective security aspects, i.e. certainty of functioning as well as development of a given subject. In a traditional approach security is considered in the context of threats and is associated with the use of force and constraint (coercion). Today, however, the approach to the character and kinds of force and constraint are changing and security perception is evolving. The feature of this evolution is the broadening of the security dimensions pertaining to the subject, object and functioning. It is commonly defined as demilitarization and extension of the security scope and content. The main security paradigms in social sciences include realism, liberalism (idealism) and constructivism. Attempting to answer the key question on the security sciences’ identity, the author proposes applying the way suggested by Max Weber from interpretation, and understanding to explaining the security phenomenon of various subjects. This approach is close to a moderate version of constructivism, however, taking into account realism and liberalism. It may create a specific methodology of a “golden mean” in security sciences.